Synthesis and structure-activity relationships of soluble 7-substituted 3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-2-amines and related ureas as dual inhibitors of the fibroblast growth factor receptor-1 and vascular endothelial growth factor receptor-2 tyrosine kinases

4628

J. Med. Chem. 2005, 48, 4628-4653

Synthesis and Structure-Activity Relationships of Soluble 7-Substituted

3-(3,5-Dimethoxyphenyl)-1,6-naphthyridin-2-amines and Related Ureas as Dual

Inhibitors of the Fibroblast Growth Factor Receptor-1 and Vascular

Endothelial Growth Factor Receptor-2 Tyrosine Kinases

Andrew M. Thompson,*^,†Amy M. Delaney,^‡James M. Hamby,^‡Mel C. Schroeder,^‡Teresa A. Spoon,^‡

Sheila M. Crean,^‡H. D. Hollis Showalter,^‡and William A. Denny^†

Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Private Bag 92019,

Auckland 1000, New Zealand, and Pfizer Global Research and Development, Ann Arbor Laboratories, 2800 Plymouth Road,

Ann Arbor, Michigan 48106-1047

Received January 31, 2005

7-Substituted 3-aryl-1,6-naphthyridine-2,7-diamines and related 2-ureas are inhibitors of

fibroblast growth factor receptor-1 (FGFR-1) and vascular endothelial growth factor receptor-2

(VEGFR-2). 3-(3,5-Dimethoxyphenyl) and 3-phenyl analogues were prepared from 7-acetamido-

2-tert-butylureas by alkylation with benzyl ω-iodoalkyl ethers, debenzylation, and amination,

followed by selective cleavage of the 7-N-acetamide. 3-(2,6-Dichlorophenyl) analogues were

prepared from the 7-fluoro-2-amine by displacement with substituted alkylamines, followed

by selective acylation of the resulting substituted naphthyridine-2,7-diamines with alkyl

isocyanates. The 3-(3,5-dimethoxyphenyl) derivatives were low nanomolar inhibitors of both

FGFR and VEGFR and were highly selective (>100-fold) over PDGFR and c-Src. Variations in

the base strength or spatial position of the 7-side chain base had only small effects on the

potency (<5-fold) or selectivity (<20-fold). The 3-(2,6-dichlorophenyl)-2-urea derivatives were

slightly less active against VEGFR and less selective, being more effective against PDGFR

(ca. 10-fold) and c-Src (ca. 500-fold). The 3-(3,5-dimethoxyphenyl)-1,6-naphthyridines were

generally more potent than the corresponding pyrido[2,3-d]pyrimidines against both VEGFR

and FGFR (2- to 20-fold), with only slightly increased PDGFR and c-Src activity. The 3-(3,5-

dimethoxyphenyl)-1,6-naphthyridine 2-ureas were also low nanomolar inhibitors of the growth

of human umbilical vein endothelial cells (HUVECs) stimulated by serum, FGF, or VEGF, at

concentrations that did not affect the growth of representative tumor cell lines, and were more

(3- to 65-fold) potent than the corresponding pyrido[2,3-d]pyrimidines.

Introduction

onstrated using blocking antibodies and dominant-

negative strategies.^20,21Thus, the inhibition of FGF and

VEGF receptor tyrosine kinases is a potentially effective

strategy to develop new antiangiogenic agents as anti-

cancer drugs.²²

Several small-molecule inhibitors of VEGFR kinases

have been reported to be in advanced development.^23,24

The indolin-2-ones SU5416 (1) and SU6668 (2) repre-

sent potent inhibitors of VEGFR-1, -2, and -3, as well

as platelet-derived growth factor receptor kinase-â

(PDGFR-â), also implicated in angiogenesis, and colony

Angiogenesis, the formation of new blood vessels from

existing vasculature, plays a major role in the progres-

sion of many human diseases, including cancer, where

it is essential for the growth and survival of solid

tumors.^1,2A number of polypeptide growth factors are

involved in mediating this process.^3-5Among the most

potent and important of these are members of the

fibroblast growth factor (FGF) and vascular endothelial

growth factor (VEGF) families.⁶These exert their effect

through cell surface receptors (FGFRs and VEGFRs)

that have protein tyrosine kinase activity.^7-9Overex-

pression of FGFRs, their ligands, or other aberrant

kinase function has been implicated in various diseases,

including not only human tumors (e.g., breast,¹⁰pros-

tate,¹¹and pancreatic¹²cancers) but also rheumatoid

arthritis¹³and atherosclerosis.¹⁴Similarly, both VEGFs

and their receptors have been implicated in the angio-

genesis of many solid tumors (e.g., glioma,¹⁵breast,¹⁶

bladder,¹⁷and colon¹⁸) as well as hematopoietic tu-

mors,¹⁹and inhibition of tumor growth has been dem-

stimulating factor receptor-1 kinase (CSF-1R) (IC₅₀

)

10-250 nM).²³Both compounds showed broad-spectrum

antitumor efficacy,^25,26and clinical responses to SU5416

have been seen in patients with acute myeloid leuke-

mia,²⁷renal carcinoma, and soft tissue sarcoma.²⁸A new

analogue with improved solubility properties, SU11248

(3), provided similar potency, selectivity, and antitumor

effects^29,30and is reportedly showing promise in early

clinical evaluation as an oral agent (phase I/II). The

4-anilinoquinazoline ZD6474 (4), a dual inhibitor of

EGFR and VEGFR-2 (IC₅₀values of 16 and 17 nM,

respectively²³), also has broad-spectrum antitumor ac-

tivity³¹and is progressing into phase III clinical trial.

The anilinophthalazine PTK787/ZK222584 (5) is a much

more selective VEGFR inhibitor (KDR IC₅₀) 37 nM)

* To whom correspondence should be addressed. Phone: +64-9-373-

7599, extension 86145. Fax: +64-9-373-7502. E-mail: am.thompson@

auckland.ac.nz.

^†The University of Auckland.

^‡Ann Arbor Laboratories.

Published on Web 06/17/2005

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4629

with antitumor properties,³²having oral activity, and

has shown encouraging clinical responses in colorectal

cancer (phase III clinical evaluation has commenced).³³

A cocrystal structure of the VEGFR-2 enzyme contain-

ing the structurally related anthranilimide inhibitor

AAL993 (6) (VEGFR-2 and -3 IC₅₀values of 23 and 18

nM, respectively) shows that the drug binds to an

inactive conformation of the protein, possibly accounting

for the high selectivity of these inhibitors.²³The isothia-

zole CP-547632 (7) was recently identified as a potent

dual inhibitor of the VEGFR-2 and FGFR-2 kinases

(IC₅₀values of 11 and 9 nM, respectively). It has oral

activity in a range of human xenografts in nude mice

and is reported to be in phase I/II clinical trial.³⁴Finally,

the pyrrolocarbazole CEP-5214 (8) also has very potent

pan-VEGFR kinase inhibitory activity (IC₅₀values of

16, 8, and 4 nM against human VEGFR-1, -2, and -3

kinases, respectively) and antitumor effects,³⁵and the

water-soluble dimethylglycine ester prodrug derivative,

CEP-7055 (9), of this is in phase I clinical trial.³⁶

tivity in vitro, being a potent inhibitor of growth,

microcapillary formation, and invasion of human um-

bilical vein endothelial cells (HUVECs) and suppressed

tumor growth in vivo.⁴¹The 7-(morpholinopropylamino)

derivative 14 (Table 1), which possessed improved

aqueous solubility, retained good potency (FGFR IC₅₀

) 31 nM) and displayed better selectivity than 13 for

FGFR. These compounds (and the related pyrido[2,3-

d]pyrimidines) have now also been found to be very

potent inhibitors of VEGFR-2 (Flk-1/KDR) (e.g., 13 and

14 IC₅₀values of 3 and 9 nM, respectively) so that they

can be considered as dual FGFR/VEGFR inhibitors.

Given the known redundancy in angiogenic signaling

pathways that allows larger tumors to switch angiogenic

factors,¹⁶such dual inhibitors may prove to be advanta-

geous in the clinical development of an effective anti-

angiogenic agent.

The promising results above prompted us to carry out

a more extensive SAR study in the naphthyridine series,

particularly focusing on a range of soluble alkylamino

derivatives related to 14. Selected analogues in the

3-phenyl and 3-(2,6-dichlorophenyl) series were also

prepared and evaluated for comparative purposes. We

describe here the synthesis, SAR, and further biological

evaluation of these compounds alongside related pyrido-

[2,3-d]pyrimidine analogues.

Chemistry

6-(3,5-Dimethoxyphenyl) Analogues. The most

attractive route to 7-substituted naphthyridines was via

an intermediate with a displaceable 7-halo group for

direct reaction with the appropriate amines. We had

developed a diazotization route⁴²to 7-chloro or 7-fluoro

derivatives in the 3-(2,6-dichlorophenyl) and 3-phenyl

series, starting from 1,6-naphthyridine-2,7-diamines.

However, initial problems with diazotization of the

electron-rich 3-(3,5-dimethoxyphenyl)-1,6-naphthyridine-

2,7-diamine⁴²led us to employ a less direct approach to

these compounds.⁴¹Thus, we previously described the

preparation of the 7-morpholinopropylamino derivative

14, by alkylation of acetamide 13 (obtained in two steps

from the diamine) with substituted alkyl chlorides.

However, this method was not suitable for the current

SAR study, which involved chain lengths of three to five

carbons and a wider range of solubilizing moieties,

because many of the required dialkylaminoalkyl chlo-

ride alkylating agents are difficult to obtain and un-

stable (because offacile intramolecular reaction). These

reagents are also hygroscopic, resulting in undesired

side reactions (e.g., hydrolysis, bis-alkylation).⁴¹It was

also desirable to have a more reactive reagent so that

the alkylation could be performed at lower temperature,

thereby further minimizing side reactions. Therefore,

benzyl ω-iodoalkyl ethers were selected for the alkyla-

tion reaction, enabling the preparation of all the target

compounds through a series of functional group ma-

nipulations (Schemes 1-3).

Small-molecule inhibitors of the FGFR include the

general class of 6-arylpyrido[2,3-d]pyrimidines (e.g., 10).

These are broad-spectrum ATP-competitive inhibitors

of a number of tyrosine kinase enzymes, including

PDGFR, FGFR, EGFR, and c-Src.³⁷Structure-activity

relationship (SAR) studies showed that analogues of 10

bearing a 3,5-dimethoxyphenyl substituent at C-6 (e.g.,

11) were potent and very selective inhibitors of the

FGFR-1 tyrosine kinase.³⁸A soluble analogue of 11,

PD173074 (12), displayed potent antiangiogenic and

antitumor effects^39,40(both in vitro and in vivo, being

efficacious orally in combination with photodynamic

therapy³⁹), and a crystal structure of 12 bound in the

ATP site of FGFR-1 has also been reported.⁴⁰We have

recently described⁴¹the synthesis and biological evalu-

ation of 1-deaza analogues of 11 (3-aryl-1,6-naphthyri-

dine-2,7-diamines and the corresponding 2-ureas) that

are equally potent and selective. The 7-acetamido

derivative 13 displayed substantial antiangiogenic ac-

The required known benzyl ω-iodoalkyl ethers^43-45

were prepared in good yield by monobenzylation⁴⁴of the

diols (0.35 equiv of BnCl/1.0 equiv of NaH/DMF) to give

known ω-(benzyloxy)-1-alkanols^46-48followed by iodi-

nation⁴⁹(I₂/PPh₃/imidazole/benzene). Treatment of the

preformed (assumed) dianion of acetamide urea 13

(generated from excess NaH/DMF at 20 °C) with these

iodoalkyl ethers (0-20 °C over 1-2 days) gave good

4630 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

Table 1. Structure and Kinase Inhibitory Activities of Solubilized 1,6-Naphthyridines

IC₅₀(µM)^a

compd

form

R₁

R₂

FGFR

FGFR#^b

VEGFR^b

PDGFR

c-Src

14^c

15^e

16

17

18

19

20

21

22

23

24

25

26

27^e

28

29^e

30

31

32^e

33

34

35

36

37

A

B

C

NH(CH₂)₃morph^d

NH(CH₂)₃4-Mepip^f

NH(CH₂)₃4-Mepip

NH(CH₂)₃NEt₂

NHCONHtBu

NH₂

0.031

0.044

0.021

0.024

0.060

0.030

0.024

0.087

0.024

0.025

0.033

0.070

0.028

2.2

0.012

0.083

0.021

0.005

0.008

0.007

0.006

0.046

0.013

0.006

0.009

0.010

0.006

4.6

0.009

0.18

45

50

30

16

18

15

3.6

>50

6.5

2.6

>50

27

5.0

>50

NHCONHEt

NHCONHtBu

NH₂

NHCONHEt

NHCONHtBu

NH₂

NHCONHtBu

NH(CH₂)₃4-Mep^f

NH₂

NHCONHtBu

NH₂

0.051

0.005

0.015

0.006

0.003

0.22

0.046

0.006

0.007

0.008

0.004

2.9

14

9.1

16

21

NH(CH₂)₄morph^d

NH(CH₂)₄4-Mepip^f

NH(CH₂)₄NEt₂

4.1

26

7.0

4.6

NH(CH₂)₄NEt₂

NH(CH₂)₅morph^d

NH(CH₂)₅4-Mepip^f

NH(CH₂)₅NEt₂

16

6.1

3.6

NH(CH₂)₃4-Mepip^f

NH(CH₂)₃4-Mepip

NH(CH₂)₄NEt₂

8.8

1.2

>50

12

1.6

0.19

0.14

0.054

8.7

0.23

6.8

12

23

7.3

3.1

3.6

1.4

NH(CH₂)₄NEt₂

0.30

0.20

0.18

0.45

4.7

0.54

0.62

4.0

0.16

0.48

0.11

0.069

0.019

0.042

0.014

NH(CH₂)₃4-Mepip^f

NH(CH₂)₃4-Mepip

NH(CH₂)₄NEt₂

0.12

0.22

1.8

NHCONHEt

NHCONHtBu

NH₂

NHCONHEt

NHCONHtBu

0.032

0.026

0.35

0.016

0.007

0.63

0.11

0.014

1.2

NH(CH₂)₄NEt₂

0.029

0.025

0.016

0.007

0.13

0.025

^aIC₅₀: concentration of drug (µM) that inhibits the phosphorylation of a random glutamate/tyrosine (4:1) copolymer by FGFR, VEGFR,

PDGFR, or c-Src proteins. For active compounds, values are an average of two or more separate determinations; variation was generally

(30%. ^bDELFIA assay; see Experimental Section. ^cReference 41. ^dN-Morpholinyl. ^eReference 42. ^f4-Methylpiperazin-1-yl.

Scheme 1^a

acetamide 73 (by HRFABMS and ¹H NMR), making this

route unsuitable (Ac₂O/py/20 °C gave no reaction at all).

Hydrogenolysis (H₂/Pd-C) of the benzyl ethers 38-

40 in various solvents (MeOH, EtOH, THF) proved to

be difficult because of competing ring hydrogenation (as

reported by Armarego⁵⁰for the unsubstituted 1,6-

naphthyridine), which could not be prevented and was

more problematic with shorter side chain lengths.

Considerable experimentation showed that the optimal

conditions were H₂/5% Pd-C (1.2 mass equiv)/EtOH/

20 °C/36-48 h, stopping the reaction after ca. 60% of

the starting material was consumed, to give ca. 30-40%

of the desired products after chromatography, together

with recovered starting material. After several cycles

through this process, moderate overall yields (45-51%)

of the required alcohols 44-46 were obtained, albeit in

varying purity (ca. 70, 90, and 100% for the propyl,

butyl, and pentyl derivatives, respectively). Since the

propyl alcohol 44 could not be further purified from

byproducts directly, a portion was purified by acetyla-

tion (Ac₂O/py) and chromatography of the acetate 47,

followed by mild alkaline hydrolysis (K₂CO₃/MeOH/

water). Subsequently, an alternative debenzylation

method (excess DDQ in CH₂Cl₂alone, with no added

water⁵¹), developed for the 3-phenyl analogues (see

below), was found to provide pure 44 more directly and

in higher yield (69% after reaction at 20 °C/4 days).

^a(i) NaH/DMF/20 °C/20-40 min, then benzyl ω-iodoalkyl ether/

DMF/0-20 °C/1-2 days; (ii) H₂/Pd-C/EtOH/20 °C/36-48 h or

DDQ/CH₂Cl₂/20 °C/4 days; (iii) Ac₂O/py/20 °C/14 h; (iv) K₂CO₃/

MeOH/water/20 °C/1 h; (v) MsCl/NMM/THF/20 °C/12-17 h; (vi)

amine/THF/20-52 °C/1-4 days; (vii) NaOH/MeOH/water/20 °C/

2-5 days; (viii) AcCl/NMM/THF/20 °C/21 h.

yields of the alkylated products 38-40 (73-80% on a

1.5-2 g scale), together with small amounts of the

deacetylated products 41-43 (5-9%) and recovered 13

(4-8%) (Scheme 1). Importantly, this demonstrated

both the desired selectivity for alkylation and, unlike

previous results,⁴¹almost complete retention of the

acetamide, which was required later in the synthesis.

Attempted reacetylation of the propyl benzyl ether 41

(excess AcCl/NMM/THF) gave some of the desired

product 38 (>36%), but a major side reaction was

acetylation on the urea, giving the poorly separable bis-

The major byproducts from the hydrogenolysis reac-

tions above were the 3,4-dihydro derivatives 48-53

1

(Scheme 2A), identified by HRFABMS and H and ¹³C

NMR (assigned by 2D heteronuclear multiple-quantum

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4631

Scheme 2^a

Scheme 3^a

^a(i) NaOH/dioxane/water/98 °C/5-6 days; (ii) NaH/DMSO/40-

50 °C/15 min, then EtNCO/DMSO/20 °C/1 day; (iii) NaOH/MeOH/

water/49 °C/17 h.

selective cleavage of the N,N-disubstituted acetamide

in the presence of the urea⁴¹to give the final products

(17-20, 23-26) in very good yield (74-85%) (although

a small amount of urea hydrolysis was often also

observed, which increased with stronger base and/or

higher temperatures).

The (diethylamino)propylamino compound 18 was

alternatively prepared by direct alkylation of acetamide

13 using freshly prepared and dried (by azeotroping

with dry benzene) diethylaminopropyl chloride⁵³(ca. 2

equiv/NaH/DMF/39 °C/40 h). This gave a mixture of 18

and its acetamide derivative 68, which, upon mild

alkaline hydrolysis, gave 18 in 48% overall yield.

The 1,6-naphthyridin-2-amine derivatives 15 and 21

were prepared by hydrolysis of the acetamide deriva-

tives 65 and 69 using either single or two-step proce-

dures (Scheme 3). Hydrolysis of the (diethylamino)-

butylamino derivative 69 under forcing conditions

(NaOH/dioxane/water/reflux/6 days) gave 21 directly in

very good yield (81%), but some difficulties were en-

countered in monitoring the reaction and purifying the

product because of the formation of a partly hydrolyzed

intermediate of similar polarity to the final product

(possibly the 2-amino-7-acetamide derivative). A two-

step procedure was therefore employed for the hydroly-

sis of the (4-methylpiperazinyl)propylamino analogue

65. The acetamide was first hydrolyzed (NaOH/MeOH/

water/49 °C/17 h), and then the crude product (mostly

17) was treated as above (NaOH/dioxane/water/reflux/5

days) to give 15 cleanly in excellent yield (91%).

Synthesis of the ethylureas 16 and 22 was ac-

complished in contrasting yields, using the optimized

conditions previously reported⁴¹for 3-(2,6-dichlorophe-

nyl)-1,6-naphthyridine-2,7-diamine (NaH/DMSO, then

EtNCO/DMSO). The (diethylamino)butylamino deriva-

tive 22 was obtained in good yield (77% following

chromatography and two recrystallizations to remove

a bis-urea contaminant). However, only a 37% yield of

the purified (4-methylpiperazinyl)propylamino analogue

16 could be obtained because of a much greater amount

of the bis-urea contaminant being formed. The latter

was purified by preparative reversed phase (C-18)

^a(i) DDQ/CH₂Cl₂/20 °C/3 h; (ii) NaOH/MeOH/water/20 °C/40 h;

(iii) NaH/DMF/20 °C/15 min, then 3-iodopropyl benzoate/DMF/

0-20 °C/1 day; (iv) H₂/Pd-C/EtOH/20 °C/48 h; (v) NaOH/MeOH/

water/20 °C/7 days.

coherence (HMQC) and heteronuclear multiple-bond

correlation (HMBC) experiments on 50). These dihydro

derivatives were readily dehydrogenated by treatment

with DDQ in CH₂Cl₂at 20 °C so that 44 was obtained

in quantitative yield from 51. Base hydrolysis of 50

unexpectedly gave predominantly the 3,4-dihydro-1,6-

naphthyridin-2(1H)-one 61. Further minor reduction

byproducts from the hydrogenolysis reactions were the

1,2,3,4-tetrahydro derivatives 54-59 in which the 2-urea

was removed (tert-butylurea itself was also isolated).

Even smaller amounts of the less stable acylaminals

having the 2-urea still attached were also observed

(TLC, HRFABMS) and in one case (60) purified. These

results are consistent with those reported for 2-ami-

nopyridines, 2-pyridones, and carbostyrils.⁵²

Mesylation of alcohols 44-46 (excess MsCl/1-Me

morpholine or 1-Me imidazole/THF) gave the unstable

mesylate products 62-64 essentially quantitatively,

which were used directly (Scheme 1). The use of these

mild amine bases avoided deprotonation and reaction

of the urea, while the acetamide protection of the 7-NH

was also critical, since similar mesylation of the 7-NH

analogue 77 gave a large number of products. Reaction

of the crude mesylate solutions with a large excess (75-

300 equiv) of 1-methylpiperazine, diethylamine, or

morpholine (50-52 °C/1-4 days) gave the amine dis-

placement products 65-72 in variable yield (77-85%

for the butyl and pentyl compounds but only 21-30%

for the propyl compounds because of the low stability

and higher reactivity of propyl mesylate 62). Subsequent

experimentation (described for the phenyl derivatives

below) led to a higher yield (64%) of the (4-methylpip-

erazinyl)propylamino analogue 65, by treatment of the

mesylate 62 with 1-methylpiperazine at lower temper-

ature (20 °C/1 day, then 32 °C/1 day). Mild alkaline

hydrolysis of the displacement products 65-72 (0.8-

1.0 M NaOH/MeOH/water/20 °C/2-5 days) then enabled

4632 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

Scheme 4^a

HPLC and proposed to have the acylimine structure 78

(Scheme 3) on the basis of its ¹H and ¹³C NMR chemical

shifts (assigned by 2-D HSQC and HMBC NMR experi-

ments). These were very different from those for 16

(especially for C-3, C-8, C-8a) and a previously re-

ported⁴¹(unstable) 2-phthalimide derivative 79 (espe-

cially for C-8).

The homologous alcohols 75-77 were synthesized by

various methods (Scheme 2B). 3-Iodopropyl benzoate⁵⁴

was prepared by iodination⁴⁹(I₂/PPh₃/imidazole) of

3-hydroxypropyl benzoate, which was made by monoben-

zoylation of the diol (0.17 equiv of Bz₂O/Et₃N/DMAP/

CH₂Cl₂/THF/20 °C/16 h).⁵⁵Alkylation of 13 by 3-io-

dopropyl benzoate (NaH/DMF/0-20 °C/1 day) gave the

propyl alcohol 75 directly, albeit in moderate yield

(40%). In this case, hydrolysis of both the benzoate ester

and acetamide functionalities occurred during alkyla-

tion, and only a small amount (7%) of the benzoate ester

product 74 was obtained, along with recovered 13 (32%).

The butyl alcohol 76 was obtained by hydrogenolysis of

the benzyl ether derivative 42, although the reaction

was slower than for the acetamide analogue 39 and gave

a poorer yield (21% after three cycles and purification).

The pentyl alcohol 77 was obtained by hydrolysis of the

acetamide derivative 46 (84% yield).

3-Phenyl Analogues. We have previously prepared

the 7-substituted 3-phenyl-1,6-naphthyridin-2-amine 27

by reaction of 7-chloro-3-phenyl-1,6-naphthyridin-2-

amine with 3-(4-methyl-1-piperazinyl)propylamine un-

der forcing conditions (neat amine, 160 °C/5 d).⁴²How-

ever, this route gave a very poor yield (7.5%) of 27, in-

stead giving predominantly the 2,7-bis-substitution pro-

duct 29 (60%). This result was quite different from that

observed for the 3-(2,6-dichlorophenyl) series,⁴²where

more selective reaction at C-7 was achieved probably

because of a greater steric crowding of the C-2 position.

The target amines and ureas in the 3-phenyl series were

therefore prepared by a route similar to that described

above.

^a(i) Ac₂O/py/20 °C/10 h; (ii) NaH/DMF/20 °C/30 min, then benzyl

ω-iodoalkyl ether/DMF/0-20 °C/2.5 days; (iii) DDQ/CH₂Cl₂/20 °C/

2-4 days; (iv) MsCl/NMM/THF/20 °C/12-16 h; (v) amine/THF/

20-50 °C/2-4 days; (vi) NaOH/MeOH/water/20 °C/3.5-4 days;

(vii) NaOH/MeOH/water/52 °C/18 h, then NaOH/dioxane/water/

96 °C/4 days; (viii) NaOH/dioxane/water/97 °C/7 days; (ix) H₂/Pd-

C/EtOH/20 °C/48 h; (x) BF₃‚Et₂O/EtSH/CH₂Cl₂/20 °C/2 days; (xi)

FeCl₃/CH₂Cl₂/20 °C/1 h.

cases, but also significant (39-100%) loss of the tert-

butyl group, to give the urea 91. The oxidants PCC⁵⁸

and PDC gave little reaction, while RuO₂/NaIO₄⁵⁹gave

an inseparable mixture of starting material and the

expected benzoate ester (¹H NMR and HRFABMS) in

moderate yield (63%), together with more polar byprod-

ucts. Treatment with excess DDQ⁵¹(5 equiv/CH₂Cl₂/

water/20 °C/1 day) gave a relatively clean reaction on a

small scale to the desired alcohol 88 (63% yield with

28% recovered 86). However, on a slightly larger scale

and with a more concentrated solution, the yields

dropped markedly probably because of acid-catalyzed

decomposition resulting from the hydrolysis of DDQ.^51,60

Addition of amine bases or aqueous buffers did not give

useful results, but performing the reaction in the

absence of water⁵¹(CH₂Cl₂alone) gave a major improve-

ment in yield (due to the dramatically reduced decom-

position rate of the DDQ⁶⁰), allowing relatively clean

reaction over several days at 20 °C. Further improve-

ments were obtained by excluding light, adding a

reducing agent to the basic workup, and repeating

extractions of the basic aqueous portion after 1 and 2

days to recover the initially quinone-bound product,

which was slowly released by reaction with base. Thus,

both alcohols 87 and 88 were obtained in very good

overall yields (60% and 85%, respectively) by this

method, although the reaction of 85 to give propyl

alcohol 87 was much slower.

The reported⁴¹2-tert-butylurea 80 was prepared in

improved yield (88%), together with bis-urea 81 (2%),

by an alternative procedure^37,41[addition of the neat

isocyanate (at 0 °C) to the preformed anion of the

diamine (NaH/DMF/20 °C/20 min) followed by reaction

(20 °C/1 day)]. Acetylation of 80 (Ac₂O/py) then gave

acetamide 82 (92%), which was alkylated with benzyl

3-iodopropyl ether or benzyl 4-iodobutyl ether (NaH/

DMF/0-20 °C/2.5 days) to give the benzyl ethers 85 and

86 in good yield (63% and 75%, respectively), together

with small amounts of the NH derivatives 83 and 84

(11% and 4%, respectively) (Scheme 4). Additional minor

products were also observed, suggesting that the alky-

lation reaction was not completely selective, but these

were not isolated. Unfortunately, small-scale hydro-

genolysis of benzyl ether 86 under the optimized condi-

tions used above for the 3-(3,5-dimethoxyphenyl) ana-

logues gave a poor result, with ring hydrogenation

products predominating. Only 11% of the desired alcohol

88 was obtained, together with the dihydro derivatives

89 (39%) and 90 (23%), recovered 86 (9%), and several

more minor products. Therefore, alternative debenzy-

lation conditions were sought.

One-pot mesylation of the butyl alcohol 88 and

displacement of the crude mesylate (93) with diethy-

lamine (as above) gave 95 in excellent yield (83%).

Similar small-scale mesylation of the propyl alcohol 87

and displacement of the crude mesylate (92) with

1-methylpiperazine at a lower temperature than normal

(20 °C/1 day and then 32 °C/1 day rather than 50 °C)

gave 94 in 66% yield. Mild alkaline hydrolysis of the

acetamide derivatives 94 and 95 gave the ureas 28 and

56

Treatment of 86 with the Lewis acids FeCl₃and

BF₃‚Et₂O/EtSH⁵⁷gave complete debenzylation in both

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4633

Scheme 5^a

Scheme 6^a

^a(i) NaH/DMF/20 °C/2 min, then tBuNCO/20 °C/1.5 h; (ii)

amine/2-pentanol/120 °C/2 h; (iii) amine/2-EtO(CH₂)₂OH/135 °C/5

days; (iv) NaH/DMSO/40-50 °C/10-15 min, then EtNCO or

tBuNCO/DMSO/20 °C/16-24 h.

^a(i) 3,5-DiOMePhCH₂CN/NaH/THF/20 °C/1.5 h, then 106/20 °C/

16 h; (ii) (2-PhSO₂-3-Ph)-oxaziridine/CHCl₃/20 °C/1 day; (iii)

Et₂N(CH₂)₄NH₂/dioxane/50 °C/16 h; (iv) NaH/DMF/20 °C/1.5 h,

then tBuNCO/20 °C/16 h; (v) NaH/DMF/20 °C/1.5 h, then EtNCO/

20 °C/16 h; (vi) 4-Me-pip(CH₂)₃NH₂/dioxane/50 °C/16 h; (vii)

HO(CH₂)₃NH₂/dioxane/reflux/18 h; (viii) TBDMSCl/imidazole/

DMF/16 h; (ix) NaH/DMF/20 °C/30 min, then tBuNCO/20 °C/18

h; (x) H₂SiF₆/MeCN/THF/20 °C/2 h.

31, respectively, and complete hydrolysis using the

methods described above gave the 2-amino derivatives

27 and 30, respectively, in excellent yield.

3-(2,6-Dichlorophenyl) Analogues. The initial ap-

proach to 7-solubilized 2-tert-butylureas in this series

(34, 37) was via amine displacements on the 7-fluoro-

2-tert-butylurea derivative 97, prepared from the previ-

ously reported⁴²amine 96 (Scheme 5A), to avoid the

formation of poorly separable bis-urea contaminants

such as 78. However, amine displacement reactions on

97 (amine/2-pentanol/120 °C/2 h) instead gave predomi-

nantly the derivatized ureas 98 and 100 (75%), together

with small amounts (9-10%) of 7-substituted analogues

99 and 101. Therefore, amine 96 was first converted into

the 7-alkylamino derivatives 32⁴²and 35 (amine/2-

ethoxyethanol/135 °C/5 days) in moderate yield (36-

46%) (Scheme 5B), and then the target ureas (33, 34,

36, 37) were obtained as above (NaH/DMSO, then

EtNCO or tert-BuNCO/DMSO) in good yield (49-72%).

Pyrido[2,3-d]pyrimidines. These analogues (12,

102-105) were accessed via amine displacements on the

key methylsulfinyl derivative 108, prepared from

known^61,62aldehyde 106 by condensation with 3,5-

(dimethoxyphenyl)acetonitrile under basic conditions,

followed by oxidation of the methylsulfanyl substituent

(Scheme 6). Urea formation on the diamine derivatives,

as above, gave the desired products in good yield,

although in the case of 105, prior protection of the

hydroxyl group (as a TBDMS ether) was required.

against highly purified and phosphorylated kinase

constructs of the cytoplasmic domains of human FGFR-1

kinase (designated FGF# in Table 1) and of human

VEGFR-2 (lacking 50 residues in the kinase insert

domain⁶⁵) using assays in DELFIA (dissociation-en-

hanced lanthanide fluoroimmunoassay) format. IC₅₀is

defined as the concentration of inhibitor that reduces

by 50% the level of ³²P (from added [³²P]-ATP) incorpo-

rated into the copolymer substrate.

The 3-(3,5-dimethoxyphenyl) analogues 14-26 were

all highly selective (>100-fold, often much greater) for

FGFR and VEGFR over both PDGFR and c-Src (Table

1). Compounds with 2-amino substituents (15, 21) were

less effective against all kinases than the corresponding

2-urea analogues, as expected.⁴¹The two ethylurea

derivatives (16, 22) showed significantly lower potency

than the corresponding tert-butylurea derivatives (17,

23) against VEGFR (by 8- to 10-fold) but against the

other kinases were equivalent to or only slightly less

potent than 17 and 23.

The main interest among the tert-butylurea deriva-

tives was the comparison with the previously reported⁴¹

compound 14 as the positioning and nature of the

cationic center (from amine protonation) on the 7-sub-

stituent was varied. We had elected to investigate chain

lengths from three to five carbons and strongly (NEt₂),

moderately (Me-piperazine), and weakly (morpholide)

basic solubilizing functions, which we have found to be

effective in previous studies.⁶⁶In the event, there was

no significant effect on FGFR or VEGFR inhibition; all

of the compounds were potent (low nanomolar) inhibi-

tors, with IC₅₀values varying less than 3-fold or 5-fold,

respectively (Table 1). A chain length of four carbons

maximized PDGFR activity, while c-Src activity was

greatest for chain lengths of four or five carbons, as

found previously.⁶⁶The more weakly basic morpholides

were less effective than the corresponding NEt₂and Me-

Results and Discussion

The 7-substituted 1,6-naphthyridines 16-26, 28, 30,

31 and 33-37 (together with the previously reported^41,42

analogues 14, 15, 27, 29, 32) listed in Table 1 were

evaluated for their ability to prevent phosphorylation

of a model glutamate-tyrosine copolymer substrate by

isolated human bFGF receptor (FGFR-1),³⁸mouse

PDGF-â receptor (PDGFR), and avian c-Src tyrosine

kinase (all full length enzymes), using published meth-

ods.^38,63,64The compounds were additionally evaluated

4634 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

Table 2. Structure and Kinase Inhibitory Activities of Nonsolubilized 1,6-Naphthyridines and Their 3,4-Dihydro Derivatives

IC₅₀(µM)^a

compd

form

R

FGFR

FGFR#^b

VEGFR^b

PDGFR

c-Src

38

39

40

44

45

46

41

42

43

75

76

77

48

49

50

51

52

53

A

B

N(Ac)(CH₂)₃OBn

N(Ac)(CH₂)₄OBn

N(Ac)(CH₂)₅OBn

N(Ac)(CH₂)₃OH

N(Ac)(CH₂)₄OH

N(Ac)(CH₂)₅OH

NH(CH₂)₃OBn

NH(CH₂)₄OBn

NH(CH₂)₅OBn

NH(CH₂)₃OH

1.5

5.1

0.33

2.4

0.084

0.67

0.65

1.9

>50

32

>50

12

3.3

28

1.4

>50

0.91

1.1

8.4

13

7.5

7.6

0.19

0.26

0.33

0.004

0.008

0.010

9.0

0.18

0.096

0.005

0.008

0.006

15

3.3

0.049

0.052

0.093

>50

14

NH(CH₂)₄OH

23

NH(CH₂)₅OH

11

N(Ac)(CH₂)₃OBn

N(Ac)(CH₂)₄OBn

N(Ac)(CH₂)₅OBn

N(Ac)(CH₂)₃OH

N(Ac)(CH₂)₄OH

N(Ac)(CH₂)₅OH

>50

1.1

1.4

>50

20

55

7.9

6.6

8.7

10

7.7

20

^aIC₅₀: concentration of drug (µM) that inhibits the phosphorylation of a random glutamate/tyrosine (4:1) copolymer by FGFR, VEGFR,

PDGFR, or c-Src proteins. For active compounds, values are an average of two or more separate determinations; variation was generally

(30%. ^bDELFIA assay; see Experimental Section.

piperazine derivatives against both PDGFR (by 2- to

>10-fold) and c-Src (by 3- to >5-fold). Thus, lead

compound 14 was overall the most selective inhibitor

in this series, although compounds 17, 20, 23, and 26

were slightly more potent dual FGFR/VEGFR inhibi-

tors. Finally, as expected, all compounds tested (14, 16,

18-20, 22, 23, 25, 26) showed excellent aqueous solu-

bility (at least 40 mM as their hydrochloride salts; see

Supporting Information).

As demonstrated previously for both pyridopyrim-

idines³⁷and 1,6-naphthyridines,⁴¹the nature of the

substituents on the 3-phenyl ring are critically impor-

tant in determining the pattern of kinase activity. In

the proposed binding model⁶⁷and the crystal structure

of 12,⁴⁰this ring is buried deep in the binding cleft of

the enzymes in a pocket not used by ATP. Two residues

(Val559 and Val561 in FGFR-1, also conserved in

VEGFR-1 and VEGFR-2) whose side chains form part

of this hydrophobic pocket have been described as key

to the selectivity conferred by the 3,5-dimethoxyphenyl

substituents.⁴⁰Most protein kinases have residues with

larger side chains at one or both positions, which

modeling studies indicate would sterically interfere with

these substituents.^40,67Thus, pyridopyrimidines 12, 102,

103, and 104 also showed >100-fold selectivity for FGFR

and VEGFR over both PDGFR and c-Src (Table 3).

Additionally, these compounds showed an excellent

with the 2-urea derivatives (28, 31) about 10- to 30-fold

less potent (for both enzymes) and the 2-amino com-

pounds (27, 30) about 50- to 80-fold less potent against

FGFR and 16-fold less potent against VEGFR. Com-

pound 29, having a soluble side chain at both C-2 and

C-7, was about 3- to 5-fold less potent than the corre-

sponding 2-amino analogue 27 against all kinases.

The 3-(2,6-dichlorophenyl) derivatives 32-37 gener-

ally retained the high FGFR potencies of the 3-(3,5-

dimethoxyphenyl) compounds (except amino derivatives

32, 35) but had slightly lower VEGFR potencies (by 2-

to 10-fold), much higher c-Src activity (of similar

magnitude to their FGFR activity), and higher PDGFR

potency (by 5- to 55-fold). They thus resemble the

corresponding 3-(2,6-dichlorophenyl)pyrido[2,3-d]pyri-

midines as “pan-kinase inhibitors”.³⁷Again, the 2-amino

compounds (32, 35) were less potent, while ethylurea

derivatives (33, 36) were essentially equivalent to tert-

butylurea derivatives (34, 37) against all kinases except

VEGFR (where they were 5- to 8-fold less potent).

Overall, the urea derivatives in this series were actually

more potent (by 3- to 6-fold against c-Src, FGFR, and

PDGFR) than analogous 7-substituted 3-(2,6-dichlo-

rophenyl)-1,6-naphthyridin-2(1H)-ones, which we re-

cently reported as c-Src inhibitors.⁶⁶

Table 2 includes kinase inhibition data for some

intermediates and byproducts from syntheses of the

compounds above, briefly exploring SAR for other 7-side

chain and chromophore modifications in the 3-(3,5-

dimethoxyphenyl) series. These show that compounds

with simple alcohol side chains (75-77) are almost as

active as the base-containing analogues, suggesting

little binding role for the cationic center. These com-

pounds also have selectivity profiles similar to the

profiles of the bases for FGFR and VEGFR over both

selectivity profile over a wider range of kinases (IC₅₀

>

50 µM against EGFR, IR, MEK, and PKC).⁴⁰

The 3-phenyl analogues 27-31 had similar, albeit

moderate, levels of activity against all kinases tested

(Table 1). Compared with their 3-(3,5-dimethoxyphenyl)

counterparts, they had significantly greater activity

against PDGFR (by ca. 10-fold) and c-Src (by ca. 20- to

40-fold) but lower potency against FGFR and VEGFR,

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4635

Table 3. Comparison of the Kinase Inhibitory Activities of 1,6-Naphthyridines (A) and Pyrido[2,3-d]pyrimidines (B)

IC₅₀(µM)^a

compd

form

R₁

R₂

FGFR

FGFR#^b

VEGFR^b

PDGFR

c-Src

16

102

17

103

22

A

B

A

B

A

B

A

B

A

B

NH(CH₂)₃4-Mepip^c

NH(CH₂)₃4-Mepip

NH(CH₂)₃4-Mepip^c

NH(CH₂)₃4-Mepip

NH(CH₂)₄NEt₂

NH(CH₂)₃OH

NHCONHEt

NHCONHtBu

NHCONHEt

NHCONHtBu

0.021

0.033

0.024

0.019

0.024

0.035

0.025

0.028

0.049

0.038

0.021

0.018

0.005

0.011

0.013

0.086

0.006

0.019

0.004

0.049

0.051

0.062

0.005

0.021

0.046

0.19

0.006

0.12

0.005

0.071

30

45

14

35

9.1

26

7.0

22

4.6

20^d

>50

16

31

6.5

27

2.6

14

32

>50

104

23

12

75

105

NH(CH₂)₃OH

^aIC₅₀: concentration of drug (µM) that inhibits the phosphorylation of a random glutamate/tyrosine (4:1) copolymer by FGFR, VEGFR,

PDGFR, or c-Src proteins. For active compounds, values are an average of two or more separate determinations; variation was generally

(30%. ^bDELFIA assay; see Experimental Section. ^c4-Methylpiperazin-1-yl. ^dData from ref 40.

PDGFR and c-Src. The corresponding benzyl derivatives

(41-43) were significantly less active (by ca. 15- to 50-

fold against both FGFR and VEGFR). The N-acetyl

alcohols (44-46) demonstrated even less potency (by

350- to 1600-fold against both kinases), as expected,

because of the essential role of the exocyclic NH in

binding to the enzyme as described previously.^40,66,67

Surprisingly, however, the N-acetylbenzyl derivatives

(38-40) retained modest activity, which was only

slightly weaker than the 7-NH benzyl derivatives (41-

43). 3,4-Dihydro-1,6-naphthyridine analogues (48-53)

were generally less potent than the corresponding

unsaturated compounds (38-40, 44-46) against both

FGFR and VEGFR, suggesting that a planar bicyclic

ring system is slightly more favorable for binding in the

ATP site of these enzymes.

The kinase inhibition data for some 1,6-naphthy-

ridines and analogous pyrido[2,3-d]pyrimidines are

compared in Table 3. While the potency of both series

against FGFR is similar in the original assay, as found

previously,⁴¹the naphthyridines generally show greater

potency than the pyrido[2,3-d]pyrimidines in the new

FGFR assay and against VEGFR (by 2- to 20-fold in 4/5

cases), with only slightly (up to 5-fold) higher PDGFR

and c-Src activity.

The FGFR/VEGFR-selective 3-(3,5-dimethoxyphenyl)

compounds (14-26, 75-77) were also evaluated for

their ability to inhibit the growth of two tumor cell lines

(C6 glioma, A90 ovarian carcinoma)⁴¹and of human

umbilical vein endothelial cells (HUVECs), stimulated

by serum, FGF, or VEGF³⁹(Table 4). Overall, the

compounds displayed moderate inhibition of the FGFR-

overexpressing A90 cell line (10/16 compounds had IC₅₀

< 0.65 µM), weaker inhibition of the PDGF-dependent

C6 cell line (expressing moderate FGFR levels), but

much higher potency toward HUVECs, whose growth

has been shown to be FGF-dependent.⁶⁸(A similar

pattern of cell selectivity was previously reported for

12, allowing an assessment of its specific antiangiogenic

effects.³⁹) For both serum-stimulated HUVECs and the

A90 and C6 cell lines, the same activity trends of

2-amine < 2-ethylurea < 2-tert-butylurea were ob-

served. Many compounds, including the alcohols, dis-

played much higher potency than the lead compound

14, with analogues 20 and 24 being particularly effec-

tive. Additionally, all of the compounds tested were

active in inhibiting FGF-stimulated HUVEC growth, at

similar or slightly (up to 5-fold) higher potency levels

compared to those observed for serum-stimulated growth.

However, the compounds were significantly less potent

at inhibiting VEGF-stimulated HUVEC growth (by 7-

to 180-fold), despite their high potency in the VEGFR

enzyme assay (the reason for this is unclear, but the

activity trends correlate well; e.g., ethylureas and

diethylaminopropyl derivative 18 were less effective).

A comparison of some 1,6-naphthyridines and analogous

pyrido[2,3-d]pyrimidines (Table 5) again shows the

naphthyridines to be superior in all growth delay assays,

especially for HUVECs (by about 3- to 65-fold). These

results, together with their increased potency against

VEGFR and good selectivity profile, distinguish the 1,6-

naphthyridines from the related pyrido[2,3-d]pyrim-

idines and suggest that they should be evaluated further

as antiangiogenesis agents.

Conclusions

We have shown that 7-solubilized 3-(3,5-dimethox-

yphenyl)-1,6-naphthyridine 2-ureas are potent inhibi-

tors of both FGFR-1 and VEGFR-2, with very high

selectivity for these kinases compared with PDGFR and

c-Src. The inhibitory potencies do not vary markedly

with the nature (base strength) or disposition of the

terminal amine on the 7-substituent. This may be

advantageous in providing scope for the optimization

of pharmacokinetic properties for these compounds as

potential drugs. The flexible synthesis reported here will

further assist such development. Following the initial

alkylation, the critical second step is removal of the

O-benzyl protecting group with DDQ in the absence of

water rather than by hydrogenolysis (to avoid concomi-

tant reduction of the 1,6-naphthyridine); one-pot me-

sylation/amine displacement and selective cleavage of

the acetamide completes the synthesis.

The SAR for inhibition of VEGFR is also similar to

that of FGFR with respect to substituents on the phenyl

4636 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

Table 4. In Vitro Growth Delay Activities of 7-Substituted 1,6-Naphthyridines

IC₅₀(µM)^a

HUVEC^b

FGF

compd

R₁

R₂

serum

VEGF

0.037

A90^c

C6^d

14

15

16

17

18

19

20

21

22

23

24

25

26

75

76

77

NH(CH₂)₃morph^e

NH(CH₂)₃4-Mepip^f

NH(CH₂)₃4-Mepip

NH(CH₂)₃NEt₂

NH(CH₂)₄morph^e

NH(CH₂)₄4-Mepip^f

NH(CH₂)₄NEt₂

NH(CH₂)₅morph^e

NH(CH₂)₅4-Mepip^f

NH(CH₂)₅NEt₂

NH(CH₂)₃OH

NHCONHtBu

NH₂

0.085

0.15

0.001

1.9

3.4

9.1

7.5

1.8

4.0

2.7

1.3

5.9

3.5

2.1

2.9

0.98

1.5

1.8

1.2

3.4

6.4

NHCONHEt

NHCONHtBu

NH₂

NHCONHEt

NHCONHtBu

0.015

0.0019

0.012

0.0044

0.0004

0.13

0.014

0.0027

0.0005

0.003

0.002

0.006

0.004

0.0036

0.001

0.002

0.003

0.0027

0.88

0.073

0.28

0.082

0.066

4.8

0.33

1.7

0.35

0.20

12

0.0026

0.0005

0.002

0.53

0.043

0.091

4.5

0.56

0.34

0.17

0.20

0.056

0.042

0.63

0.002

0.19

0.0027

0.0047

0.003

0.047

0.041

0.047

NH(CH₂)₄OH

NH(CH₂)₅OH

^aIC₅₀: concentration of drug (µM) that inhibits in vitro cell growth. For active compounds, values are an average of two or more

separate determinations. ^bFGF-dependent human umbilical vein endothelial cells stimulated by serum, FGF, or VEGF (see ref 39). ^cFGFR

overexpressing human ovarian carcinoma. ^dPDGF-dependent rat glioma (expressing moderate FGFR levels). ^eN-Morpholinyl. ^f4-

Methylpiperazin-1-yl.

Table 5. Comparison of the in Vitro Growth Delay Activities of 1,6-Naphthyridines (A) and Pyrido[2,3-d]pyrimidines (B)

IC₅₀(µM)^a

HUVEC^b

compd

form

R₁

R₂

serum

FGF

VEGF

A90^c

C6^d

16

102

17

103

22

A

B

A

B

A

B

A

B

A

B

NH(CH₂)₃4-Mepip^e

NH(CH₂)₃4-Mepip

NH(CH₂)₃4-Mepip^e

NH(CH₂)₃4-Mepip

NH(CH₂)₄NEt₂

NH(CH₂)₃OH

NHCONHEt

NHCONHtBu

NHCONHEt

NHCONHtBu

0.015

0.088

0.0019

0.028

0.014

0.43

0.0027

0.015

0.006

0.037

0.0036

0.015

0.001

0.006

0.0026

0.033

0.0005

0.007

0.0027

0.020

0.88

0.93

0.073

0.22

0.53

1.8

0.043

0.19

0.047

3.0

4.8

7.5

12

6.8

0.33

4.6

4.5

25

0.56

13

0.056

6.8

1.8

7.9

3.5

>25

2.1

17

104

23

12

75

1.8

11

105

NH(CH₂)₃OH

^aIC₅₀: concentration of drug (µM) that inhibits in vitro cell growth. For active compounds, values are an average of two or more

separate determinations. ^bFGF-dependent human umbilical vein endothelial cells stimulated by serum, FGF, or VEGF (see ref 39). ^cFGFR

overexpressing human ovarian carcinoma. ^dPDGF-dependent rat glioma (expressing moderate FGFR levels). ^e4-Methylpiperazin-1-yl.

ring (3,5-diOMe > 2,6-diCl . H in potency), with both

3-(2,6-dichlorophenyl) derivatives and 3-phenyl deriva-

tives being less selective. However, inhibition of VEGFR

appears to be more sensitive to the nature of the

2-substituent (tBu urea > Et urea > NH₂). Pairwise

comparisons of solubilized 3-(3,5-dimethoxyphenyl)-1,6-

naphthyridines and the corresponding pyrido[2,3-d]-

pyrimidines show the former to have superior potencies

both against the isolated VEGFR enzyme and in HU-

VEC cultures. This confirms^41,66that the 1-aza atom of

the pyrido[2,3-d]pyrimidines is not advantageous for

inhibition of any of the kinases examined and suggests

that the 1,6-naphthyridines (e.g., 17, 23) are worthy of

further evaluation as antiangiogenesis agents.

Experimental Section

Analyses were performed by the Microchemical Laboratory,

University of Otago, Dunedin, New Zealand. Melting points

were determined using an Electrothermal model 9200 digital

melting point apparatus and are as read. NMR spectra were

measured on a Bruker DRX-400 spectrometer and referenced

to Me₄Si. Mass spectra were recorded on a Varian VG-70SE

spectrometer at nominal 5000 resolution. HPLC was carried

out using a Bondclone 10 C18 reverse-phase silica gel column,

with a Phillips PU4100M gradient elution pump and a Phillips

PU 4120 diode array detector, and eluting with the appropriate

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4637

ratios of 95% MeCN/5% water (solvent A) and 0.45 M am-

monium formate buffer (solvent B, pH 3.45).

3.48 (t, J ) 5.8 Hz, 2 H, OCH₂), 3.31 (m, 2 H, NHCH₂), 1.65

(m, 4 H, 2CH₂), 1.39 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 161.16 (s, 2

C, C-3′,5′), 159.58 (s, C-7), 152.42, 152.10 (2 s, CONH, C-2),

151.40 (d, C-5), 149.37 (s, C-8a), 138.65 (s, C-1′′), 137.49 (d,

C-4), 137.43 (s, C-1′), 128.18, 127.34 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′),

127.27 (d, C-4′′), 121.08 (s, C-3), 113.16 (s, C-4a), 107.11 (d, 2

C, C-2′,6′), 100.21 (d, C-4′), 94.68 (br d, C-8), 71.75 (t, OCH₂-

Ph), 69.43 (t, OCH₂), 55.43 (q, 2 C, 2OCH₃), 49.98 (s, C(CH₃)₃),

41.06 (t, NCH₂), 28.68 (q, 3 C, C(CH₃)₃), 26.81, 25.68 (2 t,

2CH₂). Anal. (C₃₂H₃₉N₅O₄) C, H, N.

N-[3-(Benzyloxy)propyl]-N-[2-[[(tert-butylamino)car-

bonyl]amino]-3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-

7-yl]acetamide (38). A solution of N-[2-[[(tert-butylamino)-

carbonyl]amino]-3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-7-

yl]acetamide⁴¹(13) (2.00 g, 4.58 mmol) in dry DMF (50 mL)

was treated with 60% NaH (0.75 g, 18.8 mmol). Then the

reaction flask was immediately sealed with a rubber septum,

degassed (water pump vacuum), and filled with dry N₂

(balloon), and the mixture was stirred at 20 °C for 40 min,

then at 0 °C for 1 h. A solution of benzyl 3-iodopropyl ether⁴³

(1.65 g, 5.98 mmol) in dry DMF (5 mL, then 2 × 5 mL to rinse)

was added (syringe), and then the mixture was foil-covered

and stirred at 0-20 °C for 1 day. The resulting solution was

cooled in ice, then treated with ice/aqueous NaHCO₃(250 mL)

and extracted with EtOAc (10 × 200 mL). The extracts were

evaporated to dryness, and the residue was then chromato-

graphed on silica gel. Elution with 0-0.5% MeOH/CH₂Cl₂gave

foreruns. Then further elution with 0.5% MeOH/CH₂Cl₂yielded

crude material which, upon crystallization twice from CH₂-

Cl₂/hexane, gave N-[7-[[3-(benzyloxy)propyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-2-yl]-N′-tert-butylurea (41)

(145 mg, 6%): mp (CH₂Cl₂/hexane) 135-137 °C; ¹H NMR

[(CD₃)₂SO] δ 10.23 (br s, 1 H, NH), 8.70 (s, 1 H, H-5), 7.99 (s,

1 H, H-4), 7.31 (m, 5 H, H-2′′,3′′,4′′,5′′,6′′), 7.04 (br s, 1 H, NH),

6.91 (br t, J ) 5.5 Hz, 1 H, NHCH₂), 6.63 (s, 3 H, H-2′,4′,6′),

6.40 (s, 1 H, H-8), 4.48 (s, 2 H, OCH₂Ph), 3.81 (s, 6 H, 2OCH₃),

3.56 (t, J ) 6.2 Hz, 2 H, OCH₂), 3.38 (m, 2 H, NHCH₂), 1.87

(pentet, J ) 6.5 Hz, 2 H, CH₂), 1.39 (s, 9 H, C(CH₃)₃); ¹³C NMR

δ 161.14 (s, 2 C, C-3′,5′), 159.54 (s, C-7), 152.41, 152.06 (2 s,

CONH, C-2), 151.39 (d, C-5), 149.38 (s, C-8a), 138.59 (s, C-1′′),

137.47 (d, C-4), 137.41 (s, C-1′), 128.17, 127.35 (2 d, 2 × 2 C,

C-2′′,3′′,5′′,6′′), 127.29 (d, C-4′′), 121.13 (s, C-3), 113.18 (s, C-4a),

107.10 (d, 2 C, C-2′,6′), 100.21 (d, C-4′), 94.62 (br d, C-8), 71.87

(t, OCH₂Ph), 67.53 (t, OCH₂), 55.41 (q, 2 C, 2OCH₃), 49.95 (s,

C(CH₃)₃), 38.53 (t, NCH₂), 29.08 (t, CH₂), 28.66 (q, 3 C,

C(CH₃)₃). Anal. (C₃₁H₃₇N₅O₄) C, H, N.

Further elution with 0.5-1% MeOH/CH₂Cl₂gave (after

crystallization twice) recovered 13 (160 mg, 8%).

Further elution with 1% MeOH/CH₂Cl₂gave 39 (1.99 g,

1

73%): foam; H NMR [(CD₃)₂SO] δ 9.86 (br s, 1 H, NH), 9.13

(s, 1 H, H-5), 8.35 (s, 1 H, H-4), 7.68 (s, 1 H, H-8), 7.26 (m, 6

H, NH, H-2′′,3′′,4′′,5′′,6′′), 6.70 (s, 3 H, H-2′,4′,6′), 4.39 (s, 2 H,

OCH₂Ph), 3.90 (m, 2 H, NCH₂), 3.82 (s, 6 H, 2OCH₃), 3.38 (t,

J ) 5.5 Hz, 2 H, OCH₂), 1.98 (s, 3 H, COCH₃), 1.54 (m, 4 H,

2CH₂), 1.40 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 169.29 (s, CdO),

161.20 (s, 2 C, C-3′,5′), 154.21, 153.03, 151.53 (3 s, CONH,

C-2,7), 151.29 (d, C-5), 148.80 (s, C-8a), 138.52 (s, C-1′′), 136.99

(d, C-4), 136.54 (s, C-1′), 128.06, 127.20 (2 d, 2 × 2 C,

C-2′′,3′′,5′′,6′′), 127.15 (d, C-4′′), 127.03 (s, C-3), 118.58 (s, C-4a),

115.54 (d, C-8), 107.05 (d, 2 C, C-2′,6′), 100.63 (d, C-4′), 71.63

(t, OCH₂Ph), 69.14 (t, OCH₂), 55.45 (q, 2 C, 2OCH₃), 50.15 (s,

C(CH₃)₃), 46.76 (t, NCH₂), 28.63 (q, 3 C, C(CH₃)₃), 26.40, 24.61

(2 t, 2CH₂), 22.94 (q, CH₃). Anal. (C₃₄H₄₁N₅O₅‚0.5H₂O) C, H, N.

N-[5-(Benzyloxy)pentyl]-N-[2-[[(tert-butylamino)car-

bonyl]amino]-3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-

7-yl]acetamide (40). Similar reaction of a stirred solution of

13 (1.51 g, 3.45 mmol) in dry DMF (50 mL) with 60% NaH

(0.571 g, 14.3 mmol) under N₂at 20 °C for 20 min, then at 0

°C for 40 min, followed by reaction with benzyl 5-iodopentyl

ether⁴⁵(1.31 g, 4.31 mmol) in dry DMF (5 mL, then 2 × 5 mL)

at 0-20 °C for 2 days and chromatography of the resulting

product on silica gel (eluting with 0.5-0.75% MeOH/CH₂Cl₂)

gave (after crystallization twice from CH₂Cl₂/hexane) N-[7-[[5-

(benzyloxy)pentyl]amino]-3-(3,5-dimethoxyphenyl)-1,6-naph-

thyridin-2-yl]-N′-tert-butylurea (43) (97 mg, 5%): mp (CH₂Cl₂/

Further elution with 0.5-0.75% MeOH/CH₂Cl₂yielded

crude material which, upon crystallization twice from CH₂-

Cl₂/light petroleum, gave recovered 13 (143 mg, 7%).

1

hexane) 116-117 °C; H NMR [(CD₃)₂SO] δ 10.24 (br s, 1 H,

NH), 8.69 (s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.30 (m, 5 H,

H-2′′,3′′,4′′,5′′,6′′), 7.02 (br s, 1 H, NH), 6.91 (br t, J ) 5.6 Hz,

1 H, NHCH₂), 6.63 (t, J ) 2.2 Hz, 1 H, H-4′), 6.62 (d, J ) 2.1

Hz, 2 H, H-2′,6′), 6.39 (s, 1 H, H-8), 4.44 (s, 2 H, OCH₂Ph),

3.80 (s, 6 H, 2OCH₃), 3.44 (t, J ) 6.4 Hz, 2 H, OCH₂), 3.29 (q,

J ) 6.2 Hz, 2 H, NHCH₂), 1.59 (pentet, J ) 7.0 Hz, 4 H, 2CH₂),

1.43 (m, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 161.11

(s, 2 C, C-3′,5′), 159.56 (s, C-7), 152.36, 152.02 (2 s, CONH,

C-2), 151.34 (d, C-5), 149.33 (s, C-8a), 138.63 (s, C-1′′), 137.43

(d, C-4), 137.40 (s, C-1′), 128.11, 127.29 (2 d, 2 × 2 C,

C-2′′,3′′,5′′,6′′), 127.20 (d, C-4′′), 120.99 (s, C-3), 113.07 (s, C-4a),

107.07 (d, 2 C, C-2′,6′), 100.16 (d, C-4′), 94.56 (br d, C-8), 71.71

(t, OCH₂Ph), 69.52 (t, OCH₂), 55.38 (q, 2 C, 2OCH₃), 49.91 (s,

C(CH₃)₃), 41.08 (t, NCH₂), 28.96 (t, CH₂), 28.64 (t, CH₂), 28.63

(q, 3 C, C(CH₃)₃), 23.31 (t, CH₂). Anal. (C₃₃H₄₁N₅O₄) C, H, N.

Further elution with 0.75-1% MeOH/CH₂Cl₂gave 38 (2.00

g, 75%): foam; ¹H NMR [(CD₃)₂SO] δ 9.87 (br s, 1 H, NH),

9.12 (s, 1 H, H-5), 8.34 (s, 1 H, H-4), 7.69 (s, 1 H, H-8), 7.25

(m, 6 H, NH, H-2′′,3′′,4′′,5′′,6′′), 6.70 (s, 3 H, H-2′,4′,6′), 4.35

(s, 2 H, OCH₂Ph), 3.97 (t, J ) 7.1 Hz, 2 H, NCH₂), 3.82 (s, 6

H, 2OCH₃), 3.46 (t, J ) 6.2 Hz, 2 H, OCH₂), 1.99 (s, 3 H,

COCH₃), 1.80 (pentet, J ) 6.6 Hz, 2 H, CH₂), 1.41 (s, 9 H,

C(CH₃)₃); ¹³C NMR δ 169.41 (s, CdO), 161.20 (s, 2 C, C-3′,5′),

154.35, 153.00, 151.55 (3 s, CONH, C-2,7), 151.25 (d, C-5),

148.82 (s, C-8a), 138.36 (s, C-1′′), 136.98 (d, C-4), 136.54 (s,

C-1′), 128.04, 127.19 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′), 127.17 (d,

C-4′′), 127.00 (s, C-3), 118.59 (s, C-4a), 115.50 (d, C-8), 107.05

(d, 2 C, C-2′,6′), 100.63 (d, C-4′), 71.69 (t, OCH₂Ph), 67.08 (t,

OCH₂), 55.45 (q, 2 C, 2OCH₃), 50.16 (s, C(CH₃)₃), 44.76 (t,

NCH₂), 28.65 (q, 3 C, C(CH₃)₃), 28.13 (t, CH₂), 22.93 (q, CH₃).

Anal. (C₃₃H₃₉N₅O₅) C, H, N.

Further elution with 0.75% MeOH/CH₂Cl₂gave (after

crystallization twice) recovered 13 (66 mg, 4%).

N-[4-(Benzyloxy)butyl]-N-[2-[[(tert-butylamino)carbo-

nyl]amino]-3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-7-

yl]acetamide (39). Similar reaction of a stirred solution of

13 (2.00 g, 4.58 mmol) in dry DMF (50 mL) with 60% NaH

(0.79 g, 19.8 mmol) under N₂at 20 °C for 25 min, then at 0 °C

for 35 min, followed by reaction with benzyl 4-iodobutyl ether⁴⁴

(1.66 g, 5.72 mmol) in dry DMF (5 mL, then 2 × 5 mL) at 0-20

°C for 2 days and chromatography of the resulting product on

silica gel (eluting with 0.5% MeOH/CH₂Cl₂) gave (after crystal-

lization twice from CH₂Cl₂/hexane) N-[7-[[4-(benzyloxy)butyl]-

amino]-3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-2-yl]-N′-tert-

butylurea (42) (237 mg, 9%): mp (CH₂Cl₂/hexane) 106-109

Further elution with 1-1.5% MeOH/CH₂Cl₂gave 40 (1.70

g, 80%): foam; ¹H NMR [(CD₃)₂SO] δ 9.87 (br s, 1 H, NH),

9.13 (s, 1 H, H-5), 8.35 (s, 1 H, H-4), 7.66 (s, 1 H, H-8), 7.28

(m, 6 H, NH, H-2′′,3′′,4′′,5′′,6′′), 6.70 (s, 3 H, H-2′,4′,6′), 4.40

(s, 2 H, OCH₂Ph), 3.87 (t, J ) 7.2 Hz, 2 H, NCH₂), 3.82 (s, 6

H, 2OCH₃), 3.36 (t, J ) 6.4 Hz, 2 H, OCH₂), 1.98 (s, 3 H,

COCH₃), 1.50 (pentet, J ) 7.0 Hz, 4 H, 2CH₂), 1.41 (s, 9 H,

C(CH₃)₃), 1.32 (m, 2 H, CH₂); ¹³C NMR δ 169.27 (s, CdO),

161.19 (s, 2 C, C-3′,5′), 154.24, 153.02, 151.54 (3 s, CONH,

C-2,7), 151.26 (d, C-5), 148.79 (s, C-8a), 138.58 (s, C-1′′), 136.99

(d, C-4), 136.53 (s, C-1′), 128.08, 127.20 (2 d, 2 × 2 C,

C-2′′,3′′,5′′,6′′), 127.16 (d, C-4′′), 127.01 (s, C-3), 118.56 (s, C-4a),

115.40 (d, C-8), 107.05 (d, 2 C, C-2′,6′), 100.62 (d, C-4′), 71.64

(t, OCH₂Ph), 69.35 (t, OCH₂), 55.45 (q, 2 C, 2OCH₃), 50.16 (s,

C(CH₃)₃), 46.93 (t, NCH₂), 28.75 (t, CH₂), 28.63 (q, 3 C,

C(CH₃)₃), 27.53 (t, CH₂), 22.96 (q, CH₃), 22.94 (t, CH₂). Anal.

(C₃₅H₄₃N₅O₅) C, H, N.

1

°C; H NMR [(CD₃)₂SO] δ 10.23 (br s, 1 H, NH), 8.69 (s, 1 H,

H-5), 7.98 (s, 1 H, H-4), 7.30 (m, 5 H, H-2′′,3′′,4′′,5′′,6′′), 7.02

(br s, 1 H, NH), 6.92 (br t, J ) 5.5 Hz, 1 H, NHCH₂), 6.63 (t,

J ) 2.0 Hz, 1 H, H-4′), 6.62 (d, J ) 1.8 Hz, 2 H, H-2′,6′), 6.39

(s, 1 H, H-8), 4.46 (s, 2 H, OCH₂Ph), 3.80 (s, 6 H, 2OCH₃),

4638 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-di-

methoxyphenyl)-1,6-naphthyridin-7-yl]-N-(3-hydroxypro-

pyl)acetamide (44). A solution of 38 (353 mg, 0.603 mmol)

in absolute EtOH (280 mL) was hydrogenated over 5% Pd/C

(425 mg) at 60 psi and 20 °C for 48 h. The resulting solution

was Celite filtered, washing with 25% MeOH/CH₂Cl₂. Then

the Celite and catalyst were further extracted by stirring in

refluxing 25% MeOH/CH₂Cl₂for 10 min and then refiltering

and washing as before. The filtrates were then combined, the

solvents were removed, and the residue was chromatographed

on silica gel. Elution with 0-1% MeOH/CH₂Cl₂gave foreruns,

and then further elution with 1-1.2% MeOH/CH₂Cl₂gave

recovered 38 (115 mg, 33%). Elution with 1.5-1.6% MeOH/

CH₂Cl₂gave N-[3-(benzyloxy)propyl]-N-[2-[[(tert-butylamino)-

carbonyl]amino]-3-(3,5-dimethoxyphenyl)-3,4-dihydro-1,6-naph-

thyridin-7-yl]acetamide (48) (57 mg, 16%): mp (EtOAc/hexane)

108-110 °C; ¹H NMR [(CD₃)₂SO] δ 9.90 (br s, 1 H, NH),

9.78 (br s, 1 H, NH), 8.12 (s, 1 H, H-5), 7.27 (m, 5 H,

H-2′′,3′′,4′′,5′′,6′′), 7.06 (s, 1 H, H-8), 6.33 (t, J ) 2.1 Hz, 1 H,

H-4′), 6.22 (d, J ) 2.1 Hz, 2 H, H-2′,6′), 4.35 (d, J ) 12.1 Hz,

1 H, OCHPh), 4.31 (d, J ) 12.0 Hz, 1 H, OCHPh), 3.96 (br d,

J ) 6.6 Hz, 1 H, H-3), 3.80 (t, J ) 7.3 Hz, 2 H, NCH₂), 3.59 (s,

6 H, 2OCH₃), 3.40 (t, J ) 6.2 Hz, 2 H, OCH₂), 3.27 (br dd, J )

16.7, 7.2 Hz, 1 H, H-4), 3.01 (br d, J ) 16.3 Hz, 1 H, H-4), 1.88

(s, 3 H, COCH₃), 1.70 (pentet, J ) 6.6 Hz, 2 H, CH₂), 1.36 (s,

9 H, C(CH₃)₃); ¹³C NMR δ 169.10 (s, CdO), 163.03 (s, C-2),

160.34 (s, 2 C, C-3′,5′), 155.15 (s, C-7), 152.34 (s, CONH),

151.75 (s, C-8a), 147.19 (d, C-5), 140.40 (s, C-1′), 138.39 (s,

C-1′′), 128.08, 127.32 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′), 127.22 (d,

C-4′′), 118.97 (s, C-4a), 115.08 (d, C-8), 105.30 (d, 2 C, C-2′,6′),

98.44 (d, C-4′), 71.72 (t, OCH₂Ph), 67.06 (t, OCH₂), 54.91 (q, 2

C, 2OCH₃), 49.94 (s, C(CH₃)₃), 44.33 (t, NCH₂), 39.70 (d, C-3),

28.53 (q, 3 C, C(CH₃)₃), 28.09 (t, CH₂), 27.85 (t, C-4), 22.64 (q,

CH₃). Anal. (C₃₃H₄₁N₅O₅‚H₂O) C, H, N.

mide (60) (4.5 mg, 1.5%) as an oil: ¹H NMR [(CD₃)₂SO] δ 7.92

(s, 1 H, H-5), 7.61 (br d, J ) 3.5 Hz, 1 H, NH), 6.54 (d, J ) 2.1

Hz, 2 H, H-2′,6′), 6.45 (s, 1 H, H-8), 6.37 (t, J ) 2.1 Hz, 1 H,

H-4′), 6.29 (br d, J ) 9.4 Hz, 1 H, NH), 5.66 (br s, 1 H, NH),

5.21 (dt, J ) 9.3, 3.4 Hz, 1 H, H-2), 4.48 (br s, 1 H, CH₂OH),

3.73 (s, 6 H, 2OCH₃), 3.64 (t, J ) 6.7 Hz, 2 H, NCH₂), 3.42 (m,

2 H, CH₂OH), 3.73 (s, 6 H, 2OCH₃), 3.64 (t, J ) 6.7 Hz, 2 H,

NCH₂), 3.40 (m, 2 H, CH₂OH), 3.13 (m, 1 H, H-3), 2.93 (m, 2

H, 2H-4), 1.83 (br s, 3 H, COCH₃), 1.57 (pentet, J ) 6.7 Hz, 2

H, CH₂), 1.14 (s, 9 H, (s, C(CH₃)₃); HRFABMS calcd for

C₂₆H₃₈N₅O₅m/z (MH⁺) 500.2873, found 500.2858.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-(4-hydroxy-

butyl)acetamide (45). Similar hydrogenation of 39 (398 mg,

0.664 mmol) in absolute EtOH (320 mL) over 5% Pd/C (480

mg) at 60 psi and 20 °C for 36 h and chromatography of the

resulting product on silica gel (eluting with 1-1.4% MeOH/

CH₂Cl₂) gave firstly recovered 39 (136 mg, 34%). Elution with

1.7-2% MeOH/CH₂Cl₂gave N-[4-(benzyloxy)butyl]-N-[2-[[(tert-

butylamino)carbonyl]amino]-3-(3,5-dimethoxyphenyl)-3,4-dihy-

dro-1,6-naphthyridin-7-yl]acetamide (49) (50 mg, 13%): mp

(EtOAc/hexane) 107-109.5 °C; ¹H NMR [(CD₃)₂SO] δ 9.90 (br

s, 1 H, NH), 9.78 (br s, 1 H, NH), 8.12 (s, 1 H, H-5), 7.28 (m,

5 H, H-2′′,3′′,4′′,5′′,6′′), 7.04 (s, 1 H, H-8), 6.34 (t, J ) 2.2 Hz,

1 H, H-4′), 6.21 (d, J ) 2.1 Hz, 2 H, H-2′,6′), 4.39 (s, 2 H, OCH₂-

Ph), 3.96 (br d, J ) 6.7 Hz, 1 H, H-3), 3.73 (m, 2 H, NCH₂),

3.60 (s, 6 H, 2OCH₃), 3.35 (t, J ) 5.9 Hz, 2 H, OCH₂), 3.28 (br

dd, J ) 16.8, 7.4 Hz, 1 H, H-4), 3.01 (br d, J ) 16.3 Hz, 1 H,

H-4), 1.87 (s, 3 H, COCH₃), 1.48 (m, 4 H, 2CH₂), 1.35 (s, 9 H,

C(CH₃)₃); ¹³C NMR δ 168.99 (s, CdO), 163.02 (s, C-2), 160.34

(s, 2 C, C-3′,5′), 155.05 (s, C-7), 152.36 (s, CONH), 151.73 (s,

C-8a), 147.25 (d, C-5), 140.43 (s, C-1′), 138.54 (s, C-1′′), 128.09,

127.26 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′), 127.19 (d, C-4′′), 118.93

(s, C-4a), 115.08 (d, C-8), 105.30 (d, 2 C, C-2′,6′), 98.48 (d, C-4′),

71.66 (t, OCH₂Ph), 69.13 (t, OCH₂), 54.91 (q, 2 C, 2OCH₃),

49.94 (s, C(CH₃)₃), 46.50 (t, NCH₂), 39.69 (d, C-3), 28.51 (q, 3

C, C(CH₃)₃), 27.84 (t, C-4), 26.40, 24.62 (2 t, 2CH₂), 22.63 (q,

CH₃). Anal. (C₃₄H₄₃N₅O₅‚H₂O) C, H, N.

Further elution with 2% MeOH/CH₂Cl₂gave a minor

mixture (13 mg), which was combined with similar mixtures

from subsequent repeat runs and crystallized from DMSO/

water and then EtOAc/hexane to give N-[4-(benzyloxy)butyl]-

N-[3-(3,5-dimethoxyphenyl)-1,2,3,4-tetrahydro-1,6-naphthyridin-

7-yl]acetamide (55) (19 mg, 1% overall): mp (EtOAc/hexane)

80-84 °C; ¹H NMR [(CD₃)₂SO] δ 7.81 (s, 1 H, H-5), 7.30 (m, 5

H, H-2′′,3′′,4′′,5′′,6′′), 7.03 (br d, J ) 3.1 Hz, 1 H, NH), 6.48 (d,

J ) 2.3 Hz, 2 H, H-2′,6′), 6.38 (t, J ) 2.2 Hz, 1 H, H-4′), 6.34

(s, 1 H, H-8), 4.41 (s, 2 H, OCH₂Ph), 3.72 (s, 6 H, 2OCH₃),

3.62 (t, J ) 6.6 Hz, 2 H, NCH₂), 3.39 (t, J ) 5.9 Hz, 2 H, OCH₂),

3.35 (m, 1 H, H-2), 3.25 (br dd, J ) 12.0, 9.7 Hz, 1 H, H-2),

2.87 (m, 3 H, H-3, 2H-4), 1.82 (s, 3 H, COCH₃), 1.49 (m, 4 H,

2CH₂); ¹³C NMR δ 168.75 (s, CdO), 160.45 (s, 2 C, C-3′,5′),

153.69, 151.58 (2 s, C-7,8a), 147.55 (d, C-5), 145.46 (s, C-1′),

138.59 (s, C-1′′), 128.12, 127.28 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′),

127.20 (d, C-4′′), 114.77 (s, C-4a), 105.41 (d, 2 C, C-2′,6′), 104.03

(d, C-8), 98.15 (d, C-4′), 71.66 (t, OCH₂Ph), 69.23 (t, OCH₂),

55.01 (q, 2 C, 2OCH₃), 46.29, 45.99 (2 t, C-2, NCH₂), 36.51 (d,

C-3), 30.48 (t, C-4), 26.46, 24.49 (2 t, 2CH₂), 22.38 (q, CH₃);

HRFABMS calcd for C₂₉H₃₆N₃O₄m/z (MH⁺) 490.2706, found

490.2712. Anal. (C₂₉H₃₅N₃O₄‚H₂O) C, H, N.

Further elution with 1.6-2.2% MeOH/CH₂Cl₂gave a mix-

ture of 44 and 54 (86 mg) (see below).

Further elution with 2.2-3% MeOH/CH₂Cl₂gave N-[2-

[[(tert-butylamino)carbonyl]amino]-3-(3,5-dimethoxyphenyl)-

3,4-dihydro-1,6-naphthyridin-7-yl]-N-(3-hydroxypropyl)aceta-

1

mide (51) (22 mg, 7%): mp (CH₂Cl₂/hexane) 162-164 °C; H

NMR [(CD₃)₂SO] δ 9.89 (br s, 1 H, NH), 9.78 (br s, 1 H, NH),

8.13 (s, 1 H, H-5), 7.05 (s, 1 H, H-8), 6.35 (t, J ) 2.1 Hz, 1 H,

H-4′), 6.22 (d, J ) 2.1 Hz, 2 H, H-2′,6′), 4.43 (br t, J ) 5.1 Hz,

1 H, CH₂OH), 3.96 (br d, J ) 6.3 Hz, 1 H, H-3), 3.76 (t, J )

7.2 Hz, 2 H, NCH₂), 3.61 (s, 6 H, 2OCH₃), 3.38 (m, 2 H, CH₂-

OH), 3.28 (br dd, J ) 16.1, 6.5 Hz, 1 H, H-4), 3.01 (br d, J )

16.5 Hz, 1 H, H-4), 1.88 (s, 3 H, COCH₃), 1.57 (pentet, J ) 6.8

Hz, 2 H, CH₂), 1.36 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 169.14 (s,

CdO), 163.02 (s, C-2), 160.34 (s, 2 C, C-3′,5′), 155.13 (s, C-7),

152.34 (s, CONH), 151.71 (s, C-8a), 147.16 (d, C-5), 140.45 (s,

C-1′), 118.91 (s, C-4a), 115.06 (d, C-8), 105.28 (d, 2 C, C-2′,6′),

98.52 (d, C-4′), 58.23 (t, OCH₂), 54.94 (q, 2 C, 2OCH₃), 49.95

(s, C(CH₃)₃), 44.51 (t, NCH₂), 39.68 (d, C-3), 31.04 (t, CH₂),

28.54 (q, 3 C, C(CH₃)₃), 27.81 (t, C-4), 22.66 (q, CH₃). Anal.

(C₂₆H₃₅N₅O₅) C, H, N.

Further elution with 5% MeOH/CH₂Cl₂gave N-[3-(3,5-

dimethoxyphenyl)-1,2,3,4-tetrahydro-1,6-naphthyridin-7-yl]-N-

(3-hydroxypropyl)acetamide (57) (17 mg, 7%) as an oil: ¹H

NMR [(CD₃)₂SO] δ 7.82 (s, 1 H, H-5), 7.05 (m, 1 H, NH), 6.49

(d, J ) 2.1 Hz, 2 H, H-2′,6′), 6.38 (t, J ) 2.1 Hz, 1 H, H-4′),

6.35 (s, 1 H, H-8), 4.52 (br s, 1 H, CH₂OH), 3.73 (s, 6 H,

2OCH₃), 3.65 (t, J ) 7.2 Hz, 2 H, NCH₂), 3.42 (m, 2 H, CH₂-

OH), 3.39 (m, 1 H, H-2), 3.26 (br dd, J ) 12.0, 9.7 Hz, 1 H,

H-2), 2.87 (m, 3 H, H-3, 2H-4), 1.83 (s, 3 H, COCH₃), 1.58

(pentet, J ) 6.9 Hz, 2 H, CH₂); ¹³C NMR δ 169.05 (s, CdO),

160.51 (s, 2 C, C-3′,5′), 153.83, 151.68 (2 s, C-7,8a), 147.57 (d,

C-5), 145.52 (s, C-1′), 114.89 (s, C-4a), 105.48 (d, 2 C, C-2′,6′),

104.11 (d, C-8), 98.19 (d, C-4′), 58.40 (t, OCH₂), 55.07 (q, 2 C,

2OCH₃), 46.06 (t, C-2), 44.37 (t, NCH₂), 36.55 (d, C-3), 31.00

(t, CH₂), 30.52 (t, C-4), 22.44 (q, CH₃); HRFABMS calcd for

C₂₁H₂₈N₃O₄m/z (MH⁺) 386.2080, found 386.2088.

Further elution with 2-3% MeOH/CH₂Cl₂gave the desired

1

45 (122 mg, 36%): mp (EtOAc/Et₂O/hexane) 133-135 °C; H

NMR [(CD₃)₂SO] δ 9.87 (br s, 1 H, NH), 9.14 (s, 1 H, H-5),

8.35 (s, 1 H, H-4), 7.66 (s, 1 H, H-8), 7.30 (br s, 1 H, NH), 6.71

(d, J ) 1.7 Hz, 2 H, H-2′,6′), 6.70 (t, J ) 2.0 Hz, 1 H, H-4′),

4.36 (br t, J ) 5.1 Hz, 1 H, CH₂OH), 3.88 (t, J ) 7.2 Hz, 2 H,

NCH₂), 3.82 (s, 6 H, 2OCH₃), 3.33 (m, 2 H, CH₂OH), 1.98 (s, 3

H, COCH₃), 1.50 (pentet, J ) 7.3 Hz, 2 H, CH₂), 1.42 (s, 9 H,

C(CH₃)₃), 1.39 (m, 2 H, CH₂); ¹³C NMR δ 169.29 (s, CdO),

161.21 (s, 2 C, C-3′,5′), 154.25, 153.06, 151.57 (3 s, CONH,

C-2,7), 151.31 (d, C-5), 148.82 (s, C-8a), 137.02 (d, C-4), 136.56

(s, C-1′), 127.06 (s, C-3), 118.60 (s, C-4a), 115.50 (d, C-8), 107.09

(d, 2 C, C-2′,6′), 100.64 (d, C-4′), 60.31 (t, OCH₂), 55.47 (q, 2

C, 2OCH₃), 50.20 (s, C(CH₃)₃), 46.96 (t, NCH₂), 29.69 (t, CH₂),

Further elution with 10% MeOH/CH₂Cl₂gave N-[2-[[(tert-

butylamino)carbonyl]amino]-3-(3,5-dimethoxyphenyl)-1,2,3,4-

tetrahydro-1,6-naphthyridin-7-yl]-N-(3-hydroxypropyl)aceta-

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4639

28.66 (q, 3 C, C(CH₃)₃), 24.52 (t, CH₂), 22.97 (q, CH₃). Anal.

(C₂₇H₃₅N₅O₅) C, H, N.

C(CH₃)₃); ¹³C NMR δ 158.00 (s, CONH), 48.67 (s, C(CH₃)₃),

29.14 (q, 3 C, C(CH₃)₃); HREIMS calcd for C₅H₁₂N₂O m/z (M⁺)

116.094 96, found 116.094 73.

Further elution with 3.5-4.5% MeOH/CH₂Cl₂gave N-[2-

[[(tert-butylamino)carbonyl]amino]-3-(3,5-dimethoxyphenyl)-

3,4-dihydro-1,6-naphthyridin-7-yl]-N-(4-hydroxybutyl)aceta-

mide (52) (23 mg, 7%): mp (CH₂Cl₂/hexane) 165-167.5 °C; ¹H

NMR [(CD₃)₂SO] δ 9.89 (br s, 1 H, NH), 9.78 (br s, 1 H, NH),

8.13 (s, 1 H, H-5), 7.03 (s, 1 H, H-8), 6.35 (t, J ) 2.2 Hz, 1 H,

H-4′), 6.21 (d, J ) 2.1 Hz, 2 H, H-2′,6′), 4.34 (br t, J ) 5.1 Hz,

1 H, CH₂OH), 3.96 (br d, J ) 7.0 Hz, 1 H, H-3), 3.74 (dt, J )

14.1, 7.1 Hz, 1 H, NCH), 3.69 (dt, J ) 13.8, 7.0 Hz, 1 H, NCH),

3.61 (s, 6 H, 2OCH₃), 3.33 (m, 2 H, CH₂OH), 3.28 (br dd, J )

16.7, 7.2 Hz, 1 H, H-4), 3.00 (br d, J ) 16.6 Hz, 1 H, H-4), 1.87

(s, 3 H, COCH₃), 1.40 (m, 4 H, 2CH₂), 1.36 (s, 9 H, C(CH₃)₃);

¹³C NMR δ 168.94 (s, CdO), 163.05 (s, C-2), 160.35 (s, 2 C,

C-3′,5′), 155.05 (s, C-7), 152.34 (s, CONH), 151.73 (s, C-8a),

147.23 (d, C-5), 140.45 (s, C-1′), 118.92 (s, C-4a), 115.05 (d,

C-8), 105.30 (d, 2 C, C-2′,6′), 98.50 (d, C-4′), 60.30 (t, OCH₂),

54.93 (q, 2 C, 2OCH₃), 49.96 (s, C(CH₃)₃), 46.64 (t, NCH₂), 39.71

(d, C-3), 29.66 (t, CH₂), 28.54 (q, 3 C, C(CH₃)₃), 27.83 (t, C-4),

24.47 (t, CH₂), 22.65 (q, CH₃). Anal. (C₂₇H₃₇N₅O₅) C, H, N.

Further elution with 10% MeOH/CH₂Cl₂gave N-[3-(3,5-

dimethoxyphenyl)-1,2,3,4-tetrahydro-1,6-naphthyridin-7-yl]-N-

(4-hydroxybutyl)acetamide (58) (13 mg, 5%) as an oil: ¹H NMR

[(CD₃)₂SO] δ 7.82 (s, 1 H, H-5), 7.07 (br s, 1 H, NH), 6.49 (d,

J ) 2.2 Hz, 2 H, H-2′,6′), 6.38 (t, J ) 2.2 Hz, 1 H, H-4′), 6.34

(s, 1 H, H-8), 4.37 (m, 1 H, CH₂OH), 3.73 (s, 6 H, 2OCH₃),

3.60 (t, J ) 7.3 Hz, 2 H, NCH₂), 3.36 (m, 1 H, H-2), 3.34 (m, 2

H, CH₂OH), 3.26 (br dd, J ) 12.0, 9.8 Hz, 1 H, H-2), 2.88 (m,

3 H, H-3, 2H-4), 1.82 (s, 3 H, COCH₃), 1.39 (m, 4 H, 2CH₂);

¹³C NMR δ 168.71 (s, CdO), 160.46 (s, 2 C, C-3′,5′), 153.66,

151.61 (2 s, C-7,8a), 147.49 (d, C-5), 145.48 (s, C-1′), 114.80

(s, C-4a), 105.43 (d, 2 C, C-2′,6′), 104.08 (d, C-8), 98.14 (d, C-4′),

60.36 (t, OCH₂), 55.02 (q, 2 C, 2OCH₃), 46.45, 46.00 (2 t, C-2,

NCH₂), 36.50 (d, C-3), 30.48 (t, C-4), 29.74, 24.37 (2 t, 2CH₂),

22.41 (q, CH₃); HRFABMS calcd for C₂₂H₃₀N₃O₄m/z (MH⁺)

400.2236, found 400.2247.

The remaining liquors were crystallized from DMSO/water

and then EtOAc/hexane to give N-[5-(benzyloxy)pentyl]-N-[3-

(3,5-dimethoxyphenyl)-1,2,3,4-tetrahydro-1,6-naphthyridin-7-

yl]acetamide (56) (25 mg, 2% overall): mp (EtOAc/hexane) 88-

1

90 °C; H NMR [(CD₃)₂SO] δ 7.81 (s, 1 H, H-5), 7.30 (m, 5 H,

H-2′′,3′′,4′′,5′′,6′′), 7.00 (br d, J ) 3.4 Hz, 1 H, NH), 6.48 (d, J

) 2.2 Hz, 2 H, H-2′,6′), 6.38 (t, J ) 2.2 Hz, 1 H, H-4′), 6.34 (s,

1 H, H-8), 4.42 (s, 2 H, OCH₂Ph), 3.72 (s, 6 H, 2OCH₃), 3.60

(t, J ) 7.2 Hz, 2 H, NCH₂), 3.38 (t, J ) 6.5 Hz, 2 H, OCH₂),

3.37 (m, 1 H, H-2), 3.25 (br dd, J ) 12.0, 9.8 Hz, 1 H, H-2),

2.87 (m, 3 H, H-3, 2H-4), 1.82 (s, 3 H, COCH₃), 1.51 (pentet, J

) 7.0 Hz, 2 H, CH₂), 1.42 (pentet, J ) 7.4 Hz, 2 H, CH₂), 1.28

(pentet, J ) 7.7 Hz, 2 H, CH₂); ¹³C NMR δ 168.69 (s, CdO),

160.44 (s, 2 C, C-3′,5′), 153.74, 151.54 (2 s, C-7,8a), 147.55 (d,

C-5), 145.44 (s, C-1′), 138.62 (s, C-1′′), 128.09, 127.25 (2 d, 2 ×

2 C, C-2′′,3′′,5′′,6′′), 127.17 (d, C-4′′), 114.71 (s, C-4a), 105.39

(d, 2 C, C-2′,6′), 103.96 (d, C-8), 98.14 (d, C-4′), 71.65 (t, OCH₂-

Ph), 69.42 (t, OCH₂), 54.99 (q, 2 C, 2OCH₃), 46.37, 45.98 (2 t,

C-2, NCH₂), 36.50 (d, C-3), 30.46 (t, C-4), 28.78, 27.39, 22.92

(3 t, 3CH₂), 22.38 (q, CH₃); HRFABMS calcd for C₃₀H₃₈N₃O₄

m/z (MH⁺) 504.2862, found 504.2860. Anal. (C₃₀H₃₇N₃O₄) C,

H, N.

Further elution of the column with 2-3% MeOH/CH₂Cl₂

gave the desired 46 (137 mg, 40%): mp (EtOAc/hexane) 113-

1

115 °C; H NMR [(CD₃)₂SO] δ 9.88 (br s, 1 H, NH), 9.13 (s, 1

H, H-5), 8.35 (s, 1 H, H-4), 7.66 (s, 1 H, H-8), 7.29 (br s, 1 H,

NH), 6.71 (d, J ) 2.0 Hz, 2 H, H-2′,6′), 6.70 (t, J ) 2.0 Hz, 1

H, H-4′), 4.32 (br t, J ) 5.1 Hz, 1 H, CH₂OH), 3.86 (t, J ) 7.4

Hz, 2 H, NCH₂), 3.82 (s, 6 H, 2OCH₃), 3.33 (td, J ) 6.3, 5.2

Hz, 2 H, CH₂OH), 1.98 (s, 3 H, COCH₃), 1.47 (pentet, J ) 7.5

Hz, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃), 1.37 (pentet, J ) 6.9 Hz,

2 H, CH₂), 1.28 (pentet, J ) 7.5 Hz, 2 H, CH₂); ¹³C NMR δ

169.24 (s, CdO), 161.19 (s, 2 C, C-3′,5′), 154.24, 153.04, 151.54

(3 s, CONH, C-2,7), 151.28 (d, C-5), 148.79 (s, C-8a), 136.99

(d, C-4), 136.54 (s, C-1′), 127.03 (s, C-3), 118.56 (s, C-4a), 115.43

(d, C-8), 107.07 (d, 2 C, C-2′,6′), 100.63 (d, C-4′), 60.41 (t,

OCH₂), 55.45 (q, 2 C, 2OCH₃), 50.17 (s, C(CH₃)₃), 47.04 (t,

NCH₂), 32.09 (t, CH₂), 28.64 (q, 3 C, C(CH₃)₃), 27.59 (t, CH₂),

22.96 (q, CH₃), 22.69 (t, CH₂). Anal. (C₂₈H₃₇N₅O₅‚0.5H₂O) C,

H, N.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-(5-hydroxy-

pentyl)acetamide (46). Similar hydrogenation of 40 (401 mg,

0.654 mmol) in absolute EtOH (320 mL) over 5% Pd/C (480

mg) at 60 psi and 20 °C for 48 h and chromatography of the

resulting product on silica gel (eluting with 1-1.25% MeOH/

CH₂Cl₂) gave firstly recovered 40 (156 mg, 39%). Elution with

1.5-1.8% MeOH/CH₂Cl₂gave N-[5-(benzyloxy)pentyl]-N-[2-

[[(tert-butylamino)carbonyl]amino]-3-(3,5-dimethoxyphenyl)-

3,4-dihydro-1,6-naphthyridin-7-yl]acetamide (50) (40 mg,

Further elution with 3-10% MeOH/CH₂Cl₂gave a mixture

of the above compound and more polar products (29 mg).

Chromatography of similar mixtures, combined from subse-

quent repeat runs, on silica gel, eluting with 2.5-4%

MeOH/CH₂Cl₂, gave N-[2-[[(tert-butylamino)carbonyl]amino]-

3-(3,5-dimethoxyphenyl)-3,4-dihydro-1,6-naphthyridin-7-yl]-N-

(5-hydroxypentyl)acetamide (53) (65 mg, 5% overall): mp

1

10%): mp (EtOAc/hexane) 120-121 °C; H NMR [(CD₃)₂SO]

δ 9.90 (br s, 1 H, NH), 9.79 (br s, 1 H, NH), 8.12 (s, 1 H, H-5),

7.29 (m, 5 H, H-2′′,3′′,4′′,5′′,6′′), 7.03 (s, 1 H, H-8), 6.35 (t, J )

2.1 Hz, 1 H, H-4′), 6.22 (d, J ) 2.1 Hz, 2 H, H-2′,6′), 4.40 (s, 2

H, OCH₂Ph), 3.96 (br d, J ) 6.6 Hz, 1 H, H-3), 3.76 (dt, J )

14.1, 7.1 Hz, 1 H, NCH), 3.70 (dt, J ) 13.4, 6.8 Hz, 1 H, NCH),

3.61 (s, 6 H, 2OCH₃), 3.35 (t, J ) 6.3 Hz, 2 H, OCH₂), 3.27 (br

dd, J ) 16.8, 7.4 Hz, 1 H, H-4), 3.00 (br d, J ) 16.3 Hz, 1 H,

H-4), 1.88 (s, 3 H, COCH₃), 1.47 (pentet, J ) 7.0 Hz, 2 H, CH₂),

1.38 (pentet, J ) 7.4 Hz, 2 H, CH₂), 1.36 (s, 9 H, C(CH₃)₃),

1.27 (pentet, J ) 7.7 Hz, 2 H, CH₂); ¹³C NMR δ 168.94 (s, Cd

O), 163.04 (s, C-2), 160.34 (s, 2 C, C-3′,5′), 155.04 (s, C-7),

152.33 (s, CONH), 151.72 (s, C-8a), 147.21 (d, C-5), 140.41 (s,

C-1′), 138.59 (s, C-1′′), 128.09, 127.33 (2 d, 2 × 2 C,

C-2′′,3′′,5′′,6′′), 127.18 (d, C-4′′), 118.90 (s, C-4a), 114.99 (d, C-8),

105.32 (d, 2 C, C-2′,6′), 98.43 (d, C-4′), 71.66 (t, OCH₂Ph), 69.33

(t, OCH₂), 54.91 (q, 2 C, 2OCH₃), 49.93 (s, C(CH₃)₃), 46.56 (t,

NCH₂), 39.69 (d, C-3), 28.76 (t, CH₂), 28.51 (q, 3 C, C(CH₃)₃),

27.83 (t, C-4), 27.47, 22.85 (2 t, 2CH₂), 22.66 (q, CH₃);

HRFABMS calcd for C₃₅H₄₆N₅O₅m/z (MH⁺) 616.3499, found

616.3500. Anal. (C₃₅H₄₅N₅O₅‚0.5H₂O) C, H, N.

1

(EtOAc/hexane) 138-140 °C; H NMR [(CD₃)₂SO] δ 9.90 (br

s, 1 H, NH), 9.78 (br s, 1 H, NH), 8.13 (s, 1 H, H-5), 7.03 (s, 1

H, H-8), 6.35 (t, J ) 2.1 Hz, 1 H, H-4′), 6.21 (d, J ) 2.1 Hz, 2

H, H-2′,6′), 4.32 (br t, J ) 5.2 Hz, 1 H, CH₂OH), 3.96 (br d, J

) 7.0 Hz, 1 H, H-3), 3.73 (dt, J ) 13.6, 6.8 Hz, 1 H, NCH),

3.67 (m, 1 H, NCH), 3.61 (s, 6 H, 2OCH₃), 3.32 (m, 2 H, CH₂-

OH), 3.27 (br dd, J ) 16.7, 7.2 Hz, 1 H, H-4), 3.00 (br d, J )

16.3 Hz, 1 H, H-4), 1.87 (s, 3 H, COCH₃), 1.37 (m, 4 H, 2CH₂),

1.36 (s, 9 H, C(CH₃)₃), 1.24 (m, 2 H, CH₂); ¹³C NMR δ 168.95

(s, CdO), 163.05 (s, C-2), 160.36 (s, 2 C, C-3′,5′), 155.07 (s,

C-7), 152.36 (s, CONH), 151.77 (s, C-8a), 147.26 (d, C-5), 140.45

(s, C-1′), 118.93 (s, C-4a), 115.05 (d, C-8), 105.33 (d, 2 C,

C-2′,6′), 98.47 (d, C-4′), 60.44 (t, OCH₂), 54.94 (q, 2 C, 2OCH₃),

49.97 (s, C(CH₃)₃), 46.73 (t, NCH₂), 39.69 (d, C-3), 32.13 (t,

CH₂), 28.54 (q, 3 C, C(CH₃)₃), 27.85 (t, C-4), 27.57 (t, CH₂),

22.67 (t + q, CH₂, CH₃). Anal. (C₂₈H₃₉N₅O₅) C, H, N.

Further elution of the latter column with 10% MeOH/CH₂-

Cl₂gave N-[3-(3,5-dimethoxyphenyl)-1,2,3,4-tetrahydro-1,6-

naphthyridin-7-yl]-N-(5-hydroxypentyl)acetamide (59) (65 mg,

6% overall) as an oil: ¹H NMR [(CD₃)₂SO] δ 7.81 (s, 1 H, H-5),

7.03 (m, 1 H, NH), 6.49 (d, J ) 2.1 Hz, 2 H, H-2′,6′), 6.38 (t, J

) 2.0 Hz, 1 H, H-4′), 6.33 (s, 1 H, H-8), 4.33 (br t, J ) 5.1 Hz,

1 H, CH₂OH), 3.72 (s, 6 H, 2OCH₃), 3.58 (t, J ) 7.3 Hz, 2 H,

NCH₂), 3.39 (m, 1 H, H-2), 3.36 (m, 2 H, CH₂OH), 3.26 (br dd,

Further elution with 1.8% MeOH/CH₂Cl₂gave a minor

mixture (8 mg), which was combined with similar mixtures

from subsequent repeat runs and fractionally crystallized from

CH₂Cl₂/hexane to give tert-butylurea (6 mg): mp (CH₂Cl₂/

hexane) 179-181.5 °C (lit.⁶⁹182-184 °C); ¹H NMR [(CD₃)₂-

SO] δ 5.71 (br s, 1 H, NH), 5.13 (br s, 2 H, NH₂), 1.20 (s, 9 H,

4640 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

J ) 12.0, 9.7 Hz, 1 H, H-2), 2.88 (m, 3 H, H-3, 2H-4), 1.81 (s,

3 H, COCH₃), 1.37 (pentet, J ) 7.1 Hz, 4 H, 2CH₂), 1.23

(pentet, J ) 7.2 Hz, 2 H, CH₂); ¹³C NMR δ 168.68 (s, CdO),

160.45 (s, 2 C, C-3′,5′), 153.71, 151.59 (2 s, C-7,8a), 147.52 (d,

C-5), 145.48 (s, C-1′), 114.76 (s, C-4a), 105.42 (d, 2 C, C-2′,6′),

104.01 (d, C-8), 98.13 (d, C-4′), 60.45 (t, OCH₂), 55.01 (q, 2 C,

2OCH₃), 46.53, 45.99 (2 t, C-2, NCH₂), 36.50 (d, C-3), 32.13 (t,

CH₂), 30.47 (t, C-4), 27.46, 22.69 (2 t, 2CH₂), 22.41 (q, CH₃);

HRFABMS calcd for C₂₃H₃₂N₃O₄m/z (MH⁺) 414.2393, found

414.2392.

Purification of 44 and Alternative Preparations. A.

Via Acetylation/Hydrolysis. A solution of crude 44 above

(68 mg of ca. 80%, 0.11 mmol) in pyridine (7 mL) was treated

with acetic anhydride (0.70 mL, 7.43 mmol), then the mixture

was stirred at 20 °C for 14 h. The resulting solution was

diluted with CH₂Cl₂, then treated with a mixture of ice and

aqueous NaHCO₃, and extracted with CH₂Cl₂(4 × 50 mL).

The combined extracts were washed with water and then

evaporated to dryness, and the residue was chromatographed

on silica gel. Elution with 0-1% MeOH/CH₂Cl₂gave foreruns.

Then further elution with 1-1.25% MeOH/CH₂Cl₂gave

3-[acetyl[2-[[(tert-butylamino)carbonyl]amino]-3-(3,5-dimethox-

yphenyl)-1,6-naphthyridin-7-yl]amino]propyl acetate (47) (59

mg, 100%) as an oil: ¹H NMR [(CD₃)₂SO] δ 9.86 (br s, 1 H,

NH), 9.14 (s, 1 H, H-5), 8.36 (s, 1 H, H-4), 7.71 (s, 1 H, H-8),

7.30 (br s, 1 H, NH), 6.70 (m, 3 H, H-2′,4′,6′), 4.02 (t, J ) 6.5

Hz, 2 H, OCH₂), 3.95 (t, J ) 6.9 Hz, 2 H, NCH₂), 3.82 (s, 6 H,

2OCH₃), 1.97 (s, 3 H, NCOCH₃), 1.94 (s, 3 H, OCOCH₃), 1.81

(pentet, J ) 6.7 Hz, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃);

HRFABMS calcd for C₂₈H₃₆N₅O₆m/z (MH⁺) 538.2665, found

538.2663.

aqueous portions were further extracted after 18 and 42 h (3

× 150 mL). Then the combined extracts were evaporated to

dryness, and the residue was then chromatographed on silica

gel. Elution with 0-1% MeOH/CH₂Cl₂gave foreruns, and then

further elution with 1-1.5% MeOH/CH₂Cl₂gave crude recov-

ered 38 (36 mg, 12%). Elution with 1.75-2.5% MeOH/CH₂Cl₂

gave 44 (178 mg, 69%).

C. DDQ Dehydrogenation of 51. Similar reaction of 51

(42 mg, 84.5 µmol) with DDQ (29 mg, 0.128 mmol) in CH₂Cl₂

(8 mL) at 20 °C for 3 h and then workup (as above) and

chromatography of the resulting product on silica gel (eluting

with 1-2% MeOH/CH₂Cl₂) gave 44 (41 mg, 98%).

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[3-(4-meth-

yl-1-piperazinyl)propyl]acetamide (65). A stirred solution

of (pure) 44 (217 mg, 0.438 mmol) in dry THF (30 mL) under

N₂at 0 °C was treated with dry N-methylmorpholine (1.00

mL, 9.11 mmol), followed by mesyl chloride (0.17 mL, 2.20

mmol, added dropwise by syringe). Then the mixture was

stirred at 0-20 °C for 12 h. 1-Methylpiperazine (10.0 mL, 90.3

mmol) was then added, and the mixture was stirred at 20 °C

for 1 day and then at 32 °C for 1 day. Triethylamine (1.0 mL,

7.19 mmol) was added, and the mixture was concentrated

under reduced pressure (to ca. 10 mL). The resulting solution

was cooled in ice, then treated with ice/aqueous Na₂CO₃(150

mL) and extracted with CH₂Cl₂(6 × 100 mL). The combined

extracts were evaporated to dryness, and the residue was then

chromatographed on silica gel. Elution with 0-6% MeOH/CH₂-

Cl₂gave foreruns. Then further elution with 7-8% MeOH/

CH₂Cl₂gave [after treatment with aqueous Na₂CO₃(50 mL)

and extraction with CH₂Cl₂(8 × 50 mL)] an oil (182 mg), which

was further chromatographed on silica gel. Elution with 0-3%

MeOH/EtOAc containing 1% Et₃N gave foreruns, and then

further elution with 3-6% MeOH/EtOAc containing 1% Et₃N

gave (after base washing) 65 (162 mg, 64%): oil; ¹H NMR

[(CD₃)₂SO] δ 9.89 (br s, 1 H, NH), 9.13 (s, 1 H, H-5), 8.35 (s, 1

H, H-4), 7.68 (s, 1 H, H-8), 7.30 (br s, 1 H, NH), 6.70 (s, 3 H,

H-2′,4′,6′), 3.89 (t, J ) 7.2 Hz, 2 H, NCH₂), 3.82 (s, 6 H,

2OCH₃), 2.6-2.0 (br s, 8 H, N(CH₂)₄N), 2.25 (t, J ) 7.0 Hz, 2

H, NCH₂), 2.09 (s, 3 H, NCH₃), 1.99 (s, 3 H, COCH₃), 1.63

(pentet, J ) 7.1 Hz, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃); ¹³C NMR

δ 169.42 (s, CdO), 161.21 (s, 2 C, C-3′,5′), 154.28, 153.03,

151.59 (3 s, CONH, C-2,7), 151.21 (d, C-5), 148.78 (s, C-8a),

137.01 (d, C-4), 136.56 (s, C-1′), 127.01 (s, C-3), 118.55 (s, C-4a),

115.43 (d, C-8), 107.08 (d, 2 C, C-2′,6′), 100.65 (d, C-4′), 55.47

(q, 2 C, 2OCH₃), 54.82 (t, NCH₂), 54.64, 52.45 (2 t, 2 × 2 C,

2N(CH₂)₂), 50.19 (s, C(CH₃)₃), 45.66 (q, NCH₃), 45.49 (t, NCH₂),

28.67 (q, 3 C, C(CH₃)₃), 25.10 (t, CH₂), 23.02 (q, CH₃);

HRFABMS calcd for C₃₁H₄₄N₇O₄m/z (MH⁺) 578.3455, found

578.3452.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[4-(4-meth-

yl-1-piperazinyl)butyl]acetamide (66). Similar reaction of

a stirred solution of 45 (148 mg, 0.291 mmol) and dry

N-methylmorpholine (0.50 mL, 4.55 mmol) in dry THF (20 mL)

under N₂with mesyl chloride (0.116 mL, 1.50 mmol) at 20 °C

for 16 h followed by reaction with 1-methylpiperazine (3.25

mL, 29.3 mmol) at 52 °C for 1 day and chromatography of the

resulting product on silica gel (eluting with 4-8% MeOH/

EtOAc containing 1% Et₃N) gave (after base washing) crude

66 (164 mg, <95%) as an oil: ¹H NMR [(CD₃)₂SO] δ 9.88 (br

s, 1 H, NH), 9.13 (s, 1 H, H-5), 8.36 (s, 1 H, H-4), 7.67 (s, 1 H,

H-8), 7.30 (br s, 1 H, NH), 6.70 (s, 3 H, H-2′,4′,6′), 3.88 (t, J )

6.6 Hz, 2 H, NCH₂), 3.82 (s, 6 H, 2OCH₃), 2.5-2.0 (br s, 8 H,

N(CH₂)₄N), 2.18 (t, J ) 6.7 Hz, 2 H, NCH₂), 2.09 (s, 3 H, NCH₃),

1.98 (s, 3 H, COCH₃), 1.46 (m, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃),

1.40 (m, 2 H, CH₂); ¹³C NMR δ 169.31 (s, CdO), 161.21 (s, 2

C, C-3′,5′), 154.20, 153.03, 151.56 (3 s, CONH, C-2,7), 151.29

(d, C-5), 148.80 (s, C-8a), 137.01 (d, C-4), 136.54 (s, C-1′), 127.04

(s, C-3), 118.59 (s, C-4a), 115.55 (d, C-8), 107.06 (d, 2 C, C-2′,6′),

100.63 (d, C-4′), 57.24 (t, NCH₂), 55.46 (q, 2 C, 2OCH₃), 54.66,

52.52 (2 t, 2 × 2 C, 2N(CH₂)₂), 50.18 (s, C(CH₃)₃), 46.78 (t,

NCH₂), 45.65 (q, NCH₃), 28.66 (q, 3 C, C(CH₃)₃), 25.60, 23.41

Further elution with 2-4% MeOH/CH₂Cl₂gave N-[3-(ben-

zyloxy)propyl]-N-[3-(3,5-dimethoxyphenyl)-1,2,3,4-tetrahydro-

1,6-naphthyridin-7-yl]acetamide (54) (9 mg) as an oil: ¹H NMR

[(CD₃)₂SO] δ 7.81 (s, 1 H, H-5), 7.30 (m, 5 H, H-2′′,3′′,4′′,5′′,6′′),

7.02 (br d, J ) 3.2 Hz, 1 H, NH), 6.48 (d, J ) 2.2 Hz, 2 H,

H-2′,6′), 6.38 (t, J ) 2.2 Hz, 1 H, H-4′), 6.35 (s, 1 H, H-8), 4.38

(s, 2 H, OCH₂Ph), 3.72 (s, 6 H, 2OCH₃), 3.69 (t, J ) 7.3 Hz, 2

H, NCH₂), 3.42 (t, J ) 6.3 Hz, 2 H, OCH₂), 3.37 (m, 1 H, H-2),

3.24 (m, 1 H, H-2), 2.85 (m, 3 H, H-3, 2H-4), 1.83 (s, 3 H,

COCH₃), 1.70 (pentet, J ) 6.9 Hz, 2 H, CH₂); HRFABMS calcd

for C₂₈H₃₄N₃O₄m/z (MH⁺) 476.2549, found 476.2546.

A solution of 47 (58 mg, 0.108 mmol) in MeOH (27 mL) was

treated with K₂CO₃(61 mg, 0.44 mmol) and water (3 mL),

stirring at 20 °C for 1 h. The resulting solution was diluted

with water (120 mL) and extracted with CH₂Cl₂(5 × 100 mL).

The combined extracts were washed with water (120 mL), and

then the aqueous portion was further extracted with CH₂Cl₂

(3 × 100 mL). The resulting extracts were evaporated to

dryness, and the residue was chromatographed on silica gel.

Elution with 0-1.2% MeOH/CH₂Cl₂gave foreruns, then

further elution with 1.2-3% MeOH/CH₂Cl₂gave 44 (50 mg,

1

94%): mp (EtOAc/hexane) 154-157 °C; H NMR [(CD₃)₂SO]

δ 9.89 (br s, 1 H, NH), 9.14 (s, 1 H, H-5), 8.35 (s, 1 H, H-4),

7.69 (s, 1 H, H-8), 7.30 (br s, 1 H, NH), 6.70 (s, 3 H, H-2′,4′,6′),

4.51 (br t, J ) 5.2 Hz, 1 H, CH₂OH), 3.93 (t, J ) 7.2 Hz, 2 H,

NCH₂), 3.82 (s, 6 H, 2OCH₃), 3.42 (td, J ) 6.2, 5.2 Hz, 2 H,

CH₂OH), 2.00 (s, 3 H, COCH₃), 1.65 (pentet, J ) 6.9 Hz, 2 H,

CH₂), 1.42 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 169.98 (s, CdO), 161.44

(s, 2 C, C-3′,5′), 154.42, 153.25, 151.90 (3 s, CONH, C-2,7),

151.56 (d, C-5), 149.04 (s, C-8a), 137.24 (d, C-4), 136.72 (s, C-1′),

127.29 (s, C-3), 118.86 (s, C-4a), 115.79 (d, C-8), 107.25 (d, 2

C, C-2′,6′), 100.83 (d, C-4′), 58.48 (t, OCH₂), 55.67 (q, 2 C,

2OCH₃), 50.47 (s, C(CH₃)₃), 45.09 (t, NCH₂), 31.24 (t, CH₂),

28.85 (q, 3 C, C(CH₃)₃), 23.12 (q, CH₃). Anal. (C₂₆H₃₃N₅O₅) C,

H, N.

B. DDQ Debenzylation of 38. A solution of 38 (305 mg,

0.521 mmol) and DDQ (615 mg, 2.71 mmol) in CH₂Cl₂(58 mL)

was stirred in a sealed flask (foil-covered) at 20 °C for 4 days.

The resulting solution was treated with a mixture of aqueous

Na₂CO₃/Na₂SO₃(350 mL) and extracted with CH₂Cl₂(5 × 150

mL), sequentially washing each extract with (the same)

additional solutions of aqueous Na₂CO₃/Na₂SO₃(300 mL),

aqueous Na₂CO₃(300 mL), and water (2 × 300 mL). The

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4641

(2 t, 2CH₂), 22.97 (q, CH₃); HRFABMS calcd for C₃₂H₄₆N₇O₄

(s, CdO), 161.22 (s, 2 C, C-3′,5′), 154.27, 153.05, 151.58 (3 s,

CONH, C-2,7), 151.32 (d, C-5), 148.81 (s, C-8a), 137.02 (d, C-4),

136.55 (s, C-1′), 127.06 (s, C-3), 118.61 (s, C-4a), 115.51 (d,

C-8), 107.08 (d, 2 C, C-2′,6′), 100.66 (d, C-4′), 55.47 (q, 2 C,

2OCH₃), 51.76 (t, NCH₂), 50.19 (s, C(CH₃)₃), 46.89 (t, NCH₂),

46.15 (t, 2 C, N(CH₂)₂), 28.66 (q, 3 C, C(CH₃)₃), 25.75, 23.88 (2

t, 2CH₂), 22.98 (q, CH₃), 11.67 (q, 2 C, 2CH₃); HRFABMS calcd

for C₃₁H₄₅N₆O₄m/z (MH⁺) 565.3502, found 565.3504.

m/z (MH⁺) 592.3611, found 592.3611.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[5-(4-meth-

yl-1-piperazinyl)pentyl]acetamide (67). Similar reaction

of a stirred solution of 46 (151 mg, 0.289 mmol) and dry

N-methylmorpholine (0.475 mL, 4.33 mmol) in dry THF (20

mL) under N₂with mesyl chloride (0.112 mL, 1.45 mmol) at

20 °C for 15 h followed by reaction with 1-methylpiperazine

(3.2 mL, 28.9 mmol) at 52 °C for 1 day and chromatography

of the resulting product on silica gel (eluting with 4-8%

MeOH/EtOAc containing 1% Et₃N) gave (after base washing)

crude 67 (171 mg, <98%) as an oil: ¹H NMR [(CD₃)₂SO] δ 9.88

(br s, 1 H, NH), 9.13 (s, 1 H, H-5), 8.36 (s, 1 H, H-4), 7.66 (s,

1 H, H-8), 7.30 (br s, 1 H, NH), 6.70 (s, 3 H, H-2′,4′,6′), 3.86 (t,

J ) 7.4 Hz, 2 H, NCH₂), 3.82 (s, 6 H, 2OCH₃), 2.5-2.0 (br s, 8

H, N(CH₂)₄N), 2.15 (t, J ) 7.0 Hz, 2 H, NCH₂), 2.10 (s, 3 H,

NCH₃), 1.98 (s, 3 H, COCH₃), 1.48 (pentet, J ) 6.9 Hz, 2 H,

CH₂), 1.42 (s, 9 H, C(CH₃)₃), 1.33 (pentet, J ) 7.0 Hz, 2 H,

CH₂), 1.24 (pentet, J ) 7.0 Hz, 2 H, CH₂); ¹³C NMR δ 169.29

(s, CdO), 161.22 (s, 2 C, C-3′,5′), 154.26, 153.04, 151.57 (3 s,

CONH, C-2,7), 151.30 (d, C-5), 148.81 (s, C-8a), 137.02 (d, C-4),

136.54 (s, C-1′), 127.04 (s, C-3), 118.59 (s, C-4a), 115.48 (d,

C-8), 107.07 (d, 2 C, C-2′,6′), 100.63 (d, C-4′), 57.68 (t, NCH₂),

55.46 (q, 2 C, 2OCH₃), 54.67, 52.61 (2 t, 2 × 2 C, 2N(CH₂)₂),

50.19 (s, C(CH₃)₃), 46.87 (t, NCH₂), 45.66 (q, NCH₃), 28.67 (q,

3 C, C(CH₃)₃), 27.64, 25.84, 24.10 (3 t, 3CH₂), 22.97 (q, CH₃);

HRFABMS calcd for C₃₃H₄₈N₇O₄m/z (MH⁺) 606.3768, found

606.3757.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[3-(diethy-

lamino)propyl]acetamide (68). Similar reaction of a stirred

solution of crude 44 (163 mg of ca. 70%, 0.231 mmol) and dry

N-methylmorpholine (0.57 mL, 5.19 mmol) in dry THF (20 mL)

under N₂with mesyl chloride (0.135 mL, 1.74 mmol) at 20 °C

for 16 h followed by reaction with diethylamine (7.1 mL, 68.8

mmol) at 50 °C for 42 h and chromatography of the resulting

product on silica gel (eluting with 5% MeOH/CH₂Cl₂containing

0.5% Et₃N) gave (after base washing) an oil (41 mg). Further

chromatography of this material on silica gel (eluting with

0.25-0.5% MeOH/EtOAc containing 1% Et₃N) gave (after base

washing) 68 (26 mg, 21%) as an oil: ¹H NMR [(CD₃)₂SO] δ

9.88 (br s, 1 H, NH), 9.14 (s, 1 H, H-5), 8.35 (s, 1 H, H-4), 7.67

(s, 1 H, H-8), 7.29 (br s, 1 H, NH), 6.71 (d, J ) 1.9 Hz, 2 H,

H-2′,6′), 6.69 (t, J ) 2.0 Hz, 1 H, H-4′), 3.89 (t, J ) 7.4 Hz, 2

H, NCH₂), 3.82 (s, 6 H, 2OCH₃), 2.37 (q, J ) 7.1 Hz, 4 H,

N(CH₂)₂), 2.36 (t, J ) 7.0 Hz, 2 H, NCH₂), 1.98 (s, 3 H, COCH₃),

1.59 (pentet, J ) 7.0 Hz, 2 H, CH₂), 1.41 (s, 9 H, C(CH₃)₃),

0.88 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 169.40 (s, CdO),

161.23 (s, 2 C, C-3′,5′), 154.27, 153.07, 151.60 (3 s, CONH,

C-2,7), 151.32 (d, C-5), 148.80 (s, C-8a), 137.03 (d, C-4), 136.57

(s, C-1′), 127.07 (s, C-3), 118.61 (s, C-4a), 115.54 (d, C-8), 107.09

(d, 2 C, C-2′,6′), 100.69 (d, C-4′), 55.49 (q, 2 C, 2OCH₃), 50.21

(s, C(CH₃)₃), 49.49 (t, NCH₂), 46.12 (t, 2 C, N(CH₂)₂), 45.62 (t,

NCH₂), 28.67 (q, 3 C, C(CH₃)₃), 25.45 (t, CH₂), 23.01 (q, CH₃),

11.61 (q, 2 C, 2CH₃); HRFABMS calcd for C₃₀H₄₃N₆O₄m/z

(MH⁺) 551.3346, found 551.3361.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[5-(diethy-

lamino)pentyl]acetamide (70). Similar reaction of a stirred

solution of 46 (151 mg, 0.289 mmol) and dry N-methylmor-

pholine (0.475 mL, 4.33 mmol) in dry THF (20 mL) under N₂

with mesyl chloride (0.112 mL, 1.45 mmol) at 20 °C for 15 h

followed by reaction with diethylamine (3.0 mL, 29.0 mmol)

at 50 °C for 2 days and then with additional diethylamine (3.0

mL, 29.0 mmol) at 50 °C for 2 days and chromatography of

the resulting product on silica gel (eluting with 1-2% MeOH/

EtOAc containing 1% Et₃N) gave (after base washing) 70 (141

mg, 84%) as an oil: ¹H NMR [(CD₃)₂SO] δ 9.89 (br s, 1 H, NH),

9.13 (s, 1 H, H-5), 8.35 (s, 1 H, H-4), 7.66 (s, 1 H, H-8), 7.30

(br s, 1 H, NH), 6.70 (s, 3 H, H-2′,4′,6′), 3.86 (t, J ) 7.3 Hz, 2

H, NCH₂), 3.82 (s, 6 H, 2OCH₃), 2.36 (q, J ) 7.1 Hz, 4 H,

N(CH₂)₂), 2.25 (t, J ) 7.0 Hz, 2 H, NCH₂), 1.98 (s, 3 H, COCH₃),

1.48 (pentet, J ) 7.3 Hz, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃),

1.30 (pentet, J ) 6.7 Hz, 2 H, CH₂), 1.24 (pentet, J ) 7.2 Hz,

2 H, CH₂), 0.87 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 169.24

(s, CdO), 161.20 (s, 2 C, C-3′,5′), 154.28, 153.02, 151.54 (3 s,

CONH, C-2,7), 151.28 (d, C-5), 148.78 (s, C-8a), 136.99 (d, C-4),

136.52 (s, C-1′), 127.01 (s, C-3), 118.56 (s, C-4a), 115.45 (d,

C-8), 107.05 (d, 2 C, C-2′,6′), 100.62 (d, C-4′), 55.44 (q, 2 C,

2OCH₃), 51.96 (t, NCH₂), 50.15 (s, C(CH₃)₃), 46.93 (t, NCH₂),

46.15 (t, 2 C, N(CH₂)₂), 28.63 (q, 3 C, C(CH₃)₃), 27.59, 26.17,

24.07 (3 t, 3CH₂), 22.95 (q, CH₃), 11.63 (q, 2 C, 2CH₃);

HRFABMS calcd for C₃₂H₄₇N₆O₄m/z (MH⁺) 579.3659, found

579.3646.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[4-(4-mor-

pholino)butyl]acetamide (71). Similar reaction of a stirred

solution of 45 (152 mg, 0.299 mmol) and dry N-methylmor-

pholine (0.50 mL, 4.55 mmol) in dry THF (20 mL) under N₂

with mesyl chloride (0.116 mL, 1.50 mmol) at 20 °C for 16 h

followed by reaction with morpholine (2.6 mL, 29.9 mmol) at

52 °C for 43 h and chromatography of the resulting product

on silica gel (eluting with 6-10% MeOH/EtOAc) gave (after

base washing) crude 71 (162 mg, <94%) as an oil: ¹H NMR

[(CD₃)₂SO] δ 9.87 (br s, 1 H, NH), 9.13 (s, 1 H, H-5), 8.35 (s, 1

H, H-4), 7.67 (s, 1 H, H-8), 7.30 (br s, 1 H, NH), 6.70 (s, 3 H,

H-2′,4′,6′), 3.89 (t, J ) 6.8 Hz, 2 H, NCH₂), 3.82 (s, 6 H,

2OCH₃), 3.50 (t, J ) 4.5 Hz, 4 H, O(CH₂)₂), 2.26 (m, 4 H,

N(CH₂)₂), 2.20 (t, J ) 6.8 Hz, 2 H, NCH₂), 1.98 (s, 3 H, COCH₃),

1.46 (m, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃), 1.42 (m, 2 H, CH₂);

¹³C NMR δ 169.30 (s, CdO), 161.19 (s, 2 C, C-3′,5′), 154.21,

153.03, 151.54 (3 s, CONH, C-2,7), 151.28 (d, C-5), 148.80 (s,

C-8a), 136.99 (d, C-4), 136.53 (s, C-1′), 127.03 (s, C-3), 118.57

(s, C-4a), 115.50 (d, C-8), 107.06 (d, 2 C, C-2′,6′), 100.62 (d,

C-4′), 66.08 (t, 2 C, O(CH₂)₂), 57.76 (t, NCH₂), 55.45 (q, 2 C,

2OCH₃), 53.20 (t, 2 C, N(CH₂)₂), 50.17 (s, C(CH₃)₃), 46.79 (t,

NCH₂), 28.64 (q, 3 C, C(CH₃)₃), 25.62, 23.06 (2 t, 2CH₂), 22.96

(q, CH₃); HRFABMS calcd for C₃₁H₄₃N₆O₅m/z (MH⁺) 579.3295,

found 579.3289.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[4-(diethy-

lamino)butyl]acetamide (69). Similar reaction of a stirred

solution of 45 (456 mg, 0.896 mmol) and dry N-methylmor-

pholine (1.50 mL, 13.7 mmol) in dry THF (60 mL) under N₂

with mesyl chloride (0.35 mL, 4.52 mmol) at 20 °C for 17 h

followed by reaction with diethylamine (18 mL, 0.174 mol) at

50 °C for 4 days and chromatography of the resulting product

on silica gel (eluting with 1-2% MeOH/EtOAc containing 1%

Et₃N) gave (after base washing) 69 (0.39 g, 77%) as an oil: ¹H

NMR [(CD₃)₂SO] δ 9.89 (br s, 1 H, NH), 9.13 (s, 1 H, H-5),

8.35 (s, 1 H, H-4), 7.65 (s, 1 H, H-8), 7.30 (br s, 1 H, NH), 6.70

(s, 3 H, H-2′,4′,6′), 3.88 (t, J ) 6.9 Hz, 2 H, NCH₂), 3.82 (s, 6

H, 2OCH₃), 2.36 (q, J ) 7.1 Hz, 4 H, N(CH₂)₂), 2.28 (t, J ) 7.0

Hz, 2 H, NCH₂), 1.98 (s, 3 H, COCH₃), 1.46 (pentet, J ) 7.4

Hz, 2 H, CH₂), 1.41 (s, 9 H, C(CH₃)₃), 1.36 (pentet, J ) 7.4 Hz,

2 H, CH₂), 0.87 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 169.32

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]-N-[5-(4-mor-

pholino)pentyl]acetamide (72). Similar reaction of a stirred

solution of 46 (121 mg, 0.231 mmol) and dry N-methylmor-

pholine (0.38 mL, 3.46 mmol) in dry THF (10 mL) under N₂

with mesyl chloride (0.090 mL, 1.16 mmol) at 20 °C for 16 h

followed by reaction with morpholine (2.0 mL, 23.0 mmol) at

52 °C for 36 h and chromatography of the resulting product

on silica gel (eluting with 8-10% MeOH/EtOAc) gave (after

base washing) 72 (117 mg, 85%) as an oil: ¹H NMR [(CD₃)₂-

SO] δ 9.87 (br s, 1 H, NH), 9.13 (s, 1 H, H-5), 8.35 (s, 1 H,

H-4), 7.65 (s, 1 H, H-8), 7.30 (br s, 1 H, NH), 6.69 (s, 3 H,

H-2′,4′,6′), 3.87 (t, J ) 7.3 Hz, 2 H, NCH₂), 3.82 (s, 6 H,

4642 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

2OCH₃), 3.51 (t, J ) 4.6 Hz, 4 H, O(CH₂)₂), 2.25 (m, 4 H,

N(CH₂)₂), 2.17 (t, J ) 7.2 Hz, 2 H, NCH₂), 1.98 (s, 3 H, COCH₃),

1.49 (pentet, J ) 7.4 Hz, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃),

1.36 (pentet, J ) 7.3 Hz, 2 H, CH₂), 1.26 (pentet, J ) 7.2 Hz,

2 H, CH₂); ¹³C NMR δ 169.25 (s, CdO), 161.19 (s, 2 C, C-3′,5′),

154.26, 153.03, 151.53 (3 s, CONH, C-2,7), 151.28 (d, C-5),

148.79 (s, C-8a), 137.00 (d, C-4), 136.52 (s, C-1′), 127.03 (s,

C-3), 118.56 (s, C-4a), 115.44 (d, C-8), 107.05 (d, 2 C, C-2′,6′),

100.62 (d, C-4′), 66.09 (t, 2 C, O(CH₂)₂), 58.08 (t, NCH₂), 55.44

(q, 2 C, 2OCH₃), 53.26 (t, 2 C, N(CH₂)₂), 50.16 (s, C(CH₃)₃),

46.86 (t, NCH₂), 28.64 (q, 3 C, C(CH₃)₃), 27.60, 25.47, 24.00 (3

t, 3CH₂), 22.95 (q, CH₃); HRFABMS calcd for C₃₂H₄₅N₆O₅m/z

(MH⁺) 593.3452, found 593.3490.

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[[3-(4-meth-

yl-1-piperazinyl)propyl]amino]-1,6-naphthyridin-2-yl]-

urea (17). A stirred solution of 65 (78 mg, 0.135 mmol) in

MeOH (22.5 mL) at 0 °C was treated with NaOH (0.815 g,

20.4 mmol) and water (2.5 mL, added dropwise). Then the

mixture was stirred at 0 °C for 2 h and then at 20 °C for 3

days. A solution of excess NaHCO₃(2.02 g, 24.0 mmol) in ice/

water (150 mL) was then added, and the mixture was

extracted with CH₂Cl₂(6 × 70 mL). The combined extracts

were evaporated to dryness, and the residue was then chro-

matographed on neutral alumina. Elution with CH₂Cl₂gave

foreruns. Then further elution with 1% EtOH/CHCl₃gave

material that was treated with aqueous Na₂CO₃(50 mL) and

extracted with CH₂Cl₂(5 × 50 mL). Crystallization of the

resulting solid from CH₂Cl₂/hexane gave 17 (53 mg, 73%): mp

(CH₂Cl₂/hexane) 137-139 °C; ¹H NMR [(CD₃)₂SO] δ 10.23 (br

s, 1 H, NH), 8.69 (s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.03 (br s, 1

H, NH), 6.95 (br t, J ) 5.5 Hz, 1 H, NHCH₂), 6.63 (m, 3 H,

H-2′,4′,6′), 6.38 (s, 1 H, H-8), 3.80 (s, 6 H, 2OCH₃), 3.31 (m, 2

H, NHCH₂), 2.6-2.1 (br s, 8 H, N(CH₂)₄N), 2.38 (t, J ) 7.0

Hz, 2 H, NCH₂), 2.16 (s, 3 H, NCH₃), 1.72 (pentet, J ) 6.9 Hz,

2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 161.13 (s, 2 C,

C-3′,5′), 159.55 (s, C-7), 152.39, 152.04 (2 s, CONH, C-2), 151.39

(d, C-5), 149.36 (s, C-8a), 137.46 (d, C-4), 137.39 (s, C-1′), 121.01

(s, C-3), 113.13 (s, C-4a), 107.08 (d, 2 C, C-2′,6′), 100.18 (d,

C-4′), 94.57 (br d, C-8), 55.67 (t, NCH₂), 55.40 (q, 2 C, 2OCH₃),

54.76, 52.70 (2 t, 2 × 2 C, 2N(CH₂)₂), 49.95 (s, C(CH₃)₃), 45.70

(q, NCH₃), 39.80 (t, NCH₂), 28.68 (q, 3 C, C(CH₃)₃), 25.96 (t,

CH₂). Anal. (C₂₉H₄₁N₇O₃) C, H, N.

extracted with CH₂Cl₂(7 × 50 mL). The combined extracts

were evaporated to dryness, and the residue was then chro-

matographed on silica gel. Elution with 0-0.25% MeOH/

EtOAc containing 1% Et₃N gave foreruns. Then further elution

with 0.25% MeOH/EtOAc containing 1% Et₃N gave (after base

washing) an oil (100 mg) (a mixture of 18 and 68). Similar

hydrolysis of this oil in MeOH (27 mL) with NaOH (1.06 g,

26.5 mmol) and water (3 mL) at 0 °C for 1.5 h and then at 20

°C for 44 h and chromatography of the resulting product on

silica gel (eluting with 0.3-0.5% MeOH/CH₂Cl₂containing 1%

Et₃N) gave (after base washing and crystallization) 18 (76 mg,

43%). The mother liquors were further purified by chroma-

tography on silica gel (eluting with 0.25-1% MeOH/EtOAc

containing 1% Et₃N) to give a mixture of 18 and 68, which

was subjected to base hydrolysis and workup as above. Then

the product was filtered on neutral alumina (eluting with 1%

EtOH/CHCl₃) to give additional 18 (8 mg, 5%).

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[[4-(4-mor-

pholino)butyl]amino]-1,6-naphthyridin-2-yl]urea (19).

Similar hydrolysis of crude 71 (160 mg) in MeOH (45 mL) with

NaOH (1.90 g, 47.5 mmol) and water (5 mL) at 0 °C for 2 h

and then at 20 °C for 4.5 days and chromatography of the

resulting product on silica gel (eluting with 3-3.5% MeOH/

CH₂Cl₂) gave (after base washing and crystallization) 19 (46

mg, 29% overall from 45): mp (Et₂O/hexane) 74-77 °C; ¹H

NMR [(CD₃)₂SO] δ 10.23 (br s, 1 H, NH), 8.69 (s, 1 H, H-5),

7.98 (s, 1 H, H-4), 7.02 (br s, 1 H, NH), 6.94 (br t, J ) 5.6 Hz,

1 H, NHCH₂), 6.63 (m, 3 H, H-2′,4′,6′), 6.38 (s, 1 H, H-8), 3.80

(s, 6 H, 2OCH₃), 3.56 (t, J ) 4.6 Hz, 4 H, O(CH₂)₂), 3.29 (m, 2

H, NHCH₂), 2.33 (m, 4 H, N(CH₂)₂), 2.29 (t, J ) 7.1 Hz, 2 H,

NCH₂), 1.59 (pentet, J ) 7.0 Hz, 2 H, CH₂), 1.52 (pentet, J )

6.9 Hz, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 161.11 (s,

2 C, C-3′,5′), 159.55 (s, C-7), 152.37, 152.01 (2 s, CONH, C-2),

151.34 (d, C-5), 149.33 (s, C-8a), 137.43 (d, C-4), 137.39 (s, C-1′),

121.01 (s, C-3), 113.08 (s, C-4a), 107.07 (d, 2 C, C-2′,6′), 100.16

(d, C-4′), 94.54 (br d, C-8), 66.12 (t, 2 C, O(CH₂)₂), 57.96 (t,

NCH₂), 55.38 (q, 2 C, 2OCH₃), 53.27 (t, 2 C, N(CH₂)₂), 49.92

(s, C(CH₃)₃), 41.13 (t, NCH₂), 28.65 (q, 3 C, C(CH₃)₃), 26.65,

23.48 (2 t, 2CH₂). Anal. (C₂₉H₄₀N₆O₄‚0.5H₂O) C, H, N.

Further purification of the mother liquors by chromatogra-

phy on neutral alumina (eluting with 0.25% MeOH/CH₂Cl₂)

gave additional 19 (62 mg, 39% from 45) as a foam.

Further base hydrolysis of the mother liquors, followed by

chromatography of the resulting product on neutral alumina,

as above, gave additional 17 (9 mg, 12%).

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[[4-(4-me-

thylpiperazin-1-yl)butyl]amino]-1,6-naphthyridin-2-yl]-

urea (20). Similar hydrolysis of crude 66 (164 mg) in MeOH

(45 mL) with NaOH (1.95 g, 48.8 mmol) and water (5 mL) at

0 °C for 2 h and then at 20 °C for 3 days and chromatography

of the resulting product on silica gel (eluting with 0.75-2%

MeOH/CH₂Cl₂containing 1% Et₃N) gave (after base washing

and crystallization) 20 (110 mg, 69% overall from 45): mp

(CH₂Cl₂/hexane) 148-150 °C; ¹H NMR [(CD₃)₂SO] δ 10.23 (br

s, 1 H, NH), 8.69 (s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.03 (br s, 1 H,

NH), 6.93 (br t, J ) 5.5 Hz, 1 H, NHCH₂), 6.63 (t, J ) 2.1 Hz,

1 H, H-4′), 6.62 (d, J ) 2.0 Hz, 2 H, H-2′,6′), 6.38 (s, 1 H, H-8),

3.80 (s, 6 H, 2OCH₃), 3.29 (br q, J ) 6.1 Hz, 2 H, NHCH₂),

2.6-2.0 (br s, 8 H, N(CH₂)₄N), 2.28 (t, J ) 7.0 Hz, 2 H, NCH₂),

2.13 (s, 3 H, NCH₃), 1.58 (pentet, J ) 6.7 Hz, 2 H, CH₂), 1.51

(pentet, J ) 7.1 Hz, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃); ¹³C NMR

δ 161.16 (s, 2 C, C-3′,5′), 159.58 (s, C-7), 152.41, 152.10 (2 s,

CONH, C-2), 151.41 (d, C-5), 149.39 (s, C-8a), 137.50 (d, C-4),

137.44 (s, C-1′), 121.05 (s, C-3), 113.14 (s, C-4a), 107.11 (d, 2 C,

C-2′,6′), 100.20 (d, C-4′), 94.69 (br d, C-8), 57.58 (t, NCH₂),

55.43 (q, 2 C, 2OCH₃), 54.73, 52.64 (2 t, 2 × 2 C, 2N(CH₂)₂),

49.99 (s, C(CH₃)₃), 45.72 (q, NCH₃), 41.20 (t, NCH₂), 28.70 (q, 3

C, C(CH₃)₃), 26.74, 23.93 (2 t, 2CH₂). Anal. (C₃₀H₄₃N₇O₃) C, H, N.

N-(tert-Butyl)-N′-[7-[[3-(diethylamino)propyl]amino]-

3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-2-yl]urea (18).

Method A. Similar hydrolysis of 68 (26 mg, 47.3 µmol) in

MeOH (7.2 mL) with NaOH (317 mg, 7.93 mmol) and water

(0.8 mL) at 0 °C for 1 h and then at 20 °C for 2 days and

chromatography of the resulting product on silica gel (eluting

with 0.3% MeOH/CH₂Cl₂containing 1% Et₃N) gave (after base

washing) 18 (20 mg, 83%): mp (CH₂Cl₂/hexane) 138-140 °C;

¹H NMR [(CD₃)₂SO] δ 10.22 (br s, 1 H, NH), 8.69 (s, 1 H, H-5),

7.98 (s, 1 H, H-4), 7.03 (br s, 1 H, NH), 6.96 (br t, J ) 5.5 Hz,

1 H, NHCH₂), 6.62 (m, 3 H, H-2′,4′,6′), 6.37 (s, 1 H, H-8), 3.80

(s, 6 H, 2OCH₃), 3.29 (m, 2 H, NHCH₂), 2.47 (t, J ) 7.2 Hz, 2

H, NCH₂), 2.46 (q, J ) 7.2 Hz, 4 H, N(CH₂)₂), 1.69 (pentet, J

) 6.9 Hz, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃), 0.95 (t, J ) 7.1 Hz,

6 H, 2CH₃); ¹³C NMR δ 161.12 (s, 2 C, C-3′,5′), 159.56 (s, C-7),

152.34, 152.01 (2 s, CONH, C-2), 151.39 (d, C-5), 149.41 (s,

C-8a), 137.45 (d, C-4), 137.40 (s, C-1′), 120.99 (s, C-3), 113.12

(s, C-4a), 107.07 (d, 2 C, C-2′,6′), 100.18 (d, C-4′), 94.24 (br d,

C-8), 55.39 (q, 2 C, 2OCH₃), 50.17 (t, NCH₂), 49.93 (s, C(CH₃)₃),

46.34 (t, 2 C, N(CH₂)₂), 39.89 (t, NCH₂), 28.65 (q, 3 C, C(CH₃)₃),

26.32 (t, CH₂), 11.67 (q, 2 C, 2CH₃). Anal. (C₂₈H₄₀N₆O₃) C, H, N.

N-(tert-Butyl)-N′-[7-[[4-(diethylamino)butyl]amino]-3-

(3,5-dimethoxyphenyl)-1,6-naphthyridin-2-yl]urea (23).

Similar hydrolysis of 69 (130 mg, 0.23 mmol) in MeOH (36

mL) with NaOH (1.46 g, 36.5 mmol) and water (4 mL) at 0 °C

for 2 h and then at 20 °C for 3 days and chromatography of

the resulting product on silica gel (eluting with 0.25-0.5%

MeOH/CH₂Cl₂containing 0.5-1% Et₃N) gave (after base

washing and crystallization) 23 (62 mg, 52%): mp (CH₂Cl₂/

Method B. A solution of 13 (151 mg, 0.346 mmol) in dry

DMF (10 mL) was treated with 60% NaH (90 mg, 2.25 mmol).

Then the mixture was sealed under N₂(as above) and stirred

at 20 °C for 10 min and then at 0 °C for 30 min. A solution of

3-diethylaminopropyl chloride⁵³(104 mg, 0.696 mmol) in dry

DMF (1 mL) was added (syringe), and the mixture was then

stirred at 39 °C for 40 h. The resulting solution was cooled in

ice, then treated with ice/aqueous NaHCO₃(50 mL), and

1

hexane) 113-114 °C; H NMR [(CD₃)₂SO] δ 10.23 (br s, 1 H,

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4643

NH), 8.69 (s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.02 (br s, 1 H, NH),

6.94 (br t, J ) 5.6 Hz, 1 H, NHCH₂), 6.63 (t, J ) 2.1 Hz, 1 H,

H-4′), 6.62 (d, J ) 1.7 Hz, 2 H, H-2′,6′), 6.37 (s, 1 H, H-8), 3.80

(s, 6 H, 2OCH₃), 3.28 (m, 2 H, NHCH₂), 2.44 (q, J ) 7.1 Hz, 4

H, N(CH₂)₂), 2.39 (t, J ) 7.1 Hz, 2 H, NCH₂), 1.58 (pentet, J

) 7.1 Hz, 2 H, CH₂), 1.48 (pentet, J ) 6.8 Hz, 2 H, CH₂), 1.40

(s, 9 H, C(CH₃)₃), 0.94 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ

161.12 (s, 2 C, C-3′,5′), 159.54 (s, C-7), 152.32, 152.00 (2 s,

CONH, C-2), 151.36 (d, C-5), 149.35 (s, C-8a), 137.43 (d, C-4),

137.40 (s, C-1′), 120.96 (s, C-3), 113.08 (s, C-4a), 107.06 (d, 2

C, C-2′,6′), 100.16 (d, C-4′), 94.45 (br d, C-8), 55.38 (q, 2 C,

2OCH₃), 51.99 (t, NCH₂), 49.92 (s, C(CH₃)₃), 46.17 (t, 2 C,

N(CH₂)₂), 41.15 (t, NCH₂), 28.64 (q, 3 C, C(CH₃)₃), 26.79, 24.26

(2 t, 2CH₂), 11.65 (q, 2 C, 2CH₃). Anal. (C₂₉H₄₂N₆O₃) C, H, N.

mL) with NaOH (1.83 g, 45.8 mmol) and water (5 mL) at 0 °C

for 3 h and then at 20 °C for 4 days and chromatography of

the resulting product on silica gel (eluting with 0.25% MeOH/

CH₂Cl₂containing 0.5% Et₃N) gave (after base washing and

crystallization) 26 (76 mg, 60%): mp (diisopropyl ether/hexane)

91-93.5 °C; ¹H NMR [(CD₃)₂SO] δ 10.25 (br s, 1 H, NH), 8.69

(s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.03 (br s, 1 H, NH), 6.89 (br

t, J ) 5.6 Hz, 1 H, NHCH₂), 6.63 (t, J ) 2.1 Hz, 1 H, H-4′),

6.62 (d, J ) 1.9 Hz, 2 H, H-2′,6′), 6.38 (s, 1 H, H-8), 3.81 (s, 6

H, 2OCH₃), 3.28 (br td, J ) 6.7, 6.2 Hz, 2 H, NHCH₂), 2.42 (q,

J ) 7.1 Hz, 4 H, N(CH₂)₂), 2.34 (t, J ) 7.0 Hz, 2 H, NCH₂),

1.59 (pentet, J ) 7.1 Hz, 4 H, 2CH₂), 1.40 (s, 9 H, C(CH₃)₃),

1.35 (m, 2 H, CH₂), 0.92 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR

δ 161.12 (s, 2 C, C-3′,5′), 159.56 (s, C-7), 152.36, 152.03 (2 s,

CONH, C-2), 151.34 (d, C-5), 149.33 (s, C-8a), 137.43 (d, C-4),

137.40 (s, C-1′), 120.98 (s, C-3), 113.07 (s, C-4a), 107.07 (d, 2

C, C-2′,6′), 100.17 (d, C-4′), 94.47 (br d, C-8), 55.39 (q, 2 C,

2OCH₃), 52.14 (t, NCH₂), 49.92 (s, C(CH₃)₃), 46.21 (t, 2 C,

N(CH₂)₂), 41.21 (t, NCH₂), 28.71 (t, CH₂), 28.64 (q, 3 C,

C(CH₃)₃), 26.44, 24.51 (2 t, 2CH₂), 11.67 (q, 2 C, 2CH₃). Anal.

(C₃₀H₄₄N₆O₃) C, H, N.

Further base hydrolysis of the mother liquors followed by

chromatography of the resulting product on neutral alumina

(eluting with 1% EtOH/CHCl₃) and crystallization gave ad-

ditional 23 (27 mg, 22%).

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[[5-(4-mor-

pholino)pentyl]amino]-1,6-naphthyridin-2-yl]urea (24).

Similar hydrolysis of 72 (133 mg, 0.225 mmol) in MeOH (36

mL) with NaOH (1.48 g, 37.0 mmol) and water (4 mL) at 0 °C

for 2 h and then at 20 °C for 5 days and chromatography of

the resulting product on neutral alumina (eluting with 1%

EtOH/CHCl₃) gave (after crystallization) 24 (92 mg, 74%): mp

Further purification of the mother liquors by chromatogra-

phy on neutral alumina (eluting with 1% EtOH/CHCl₃) gave

additional 26 (24 mg, 19%).

3-(3,5-Dimethoxyphenyl)-N⁷-[3-(4-methyl-1-piperazinyl)-

propyl]-1,6-naphthyridine-2,7-diamine (15). A stirred so-

lution of 65 (217 mg, 0.376 mmol) in MeOH (54 mL) was

treated with NaOH (2.40 g, 60.0 mmol) and water (6 mL), and

the mixture was then sealed under N₂and stirred at 49 °C for

17 h. The resulting mixture was concentrated under reduced

pressure (to ca. 5 mL), then treated with a solution of excess

NaHCO₃(6.0 g, 71.4 mmol) in water (150 mL) and extracted

with CH₂Cl₂(7 × 70 mL). The combined extracts were

evaporated to dryness, and the residue (mostly 17) was then

dissolved in dioxane (27 mL), treated with NaOH (2.39 g, 59.8

mmol), and water (3 mL) and then sealed under N₂and stirred

at 98 °C for 5 days. The resulting mixture was concentrated

under reduced pressure (to ca. 3 mL), then treated with excess

aqueous NaHCO₃(150 mL) and extracted with CH₂Cl₂(7 ×

70 mL) and EtOAc (2 × 70 mL). The combined extracts were

evaporated to dryness, and the residue was then chromato-

graphed on silica gel. Elution with 0-3% MeOH/CH₂Cl₂

containing 1% Et₃N gave foreruns. Then further elution with

3-5% MeOH/CH₂Cl₂containing 1% Et₃N gave (after base

washing and crystallization from CH₂Cl₂/hexane) 15⁴²(144 mg,

88%). Further purification of the mother liquors by chroma-

tography on silica gel (as above) gave (after base washing)

additional 15 (5 mg, 3%).

1

(CH₂Cl₂/hexane) 116-119.5 °C; H NMR [(CD₃)₂SO] δ 10.24

(br s, 1 H, NH), 8.69 (s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.03 (br

s, 1 H, NH), 6.90 (br t, J ) 5.5 Hz, 1 H, NHCH₂), 6.62 (m, 3 H,

H-2′,4′,6′), 6.38 (s, 1 H, H-8), 3.81 (s, 6 H, 2OCH₃), 3.55 (t, J )

4.6 Hz, 4 H, O(CH₂)₂), 3.28 (m, 2 H, NHCH₂), 2.31 (m, 4 H,

N(CH₂)₂), 2.25 (t, J ) 7.2 Hz, 2 H, NCH₂), 1.59 (pentet, J )

7.1 Hz, 2 H, CH₂), 1.46 (pentet, J ) 7.2 Hz, 2 H, CH₂), 1.40 (s,

9 H, C(CH₃)₃), 1.37 (m, 2 H, CH₂); ¹³C NMR δ 161.12 (s, 2 C,

C-3′,5′), 159.56 (s, C-7), 152.37, 152.03 (2 s, CONH, C-2), 151.34

(d, C-5), 149.33 (s, C-8a), 137.44 (d, C-4), 137.40 (s, C-1′), 121.00

(s, C-3), 113.08 (s, C-4a), 107.08 (d, 2 C, C-2′,6′), 100.16 (d,

C-4′), 94.54 (br d, C-8), 66.13 (t, 2 C, O(CH₂)₂), 58.25 (t, NCH₂),

55.39 (q, 2 C, 2OCH₃), 53.33 (t, 2 C, N(CH₂)₂), 49.93 (s,

C(CH₃)₃), 41.12 (t, NCH₂), 28.68 (t, CH₂), 28.65 (q, 3 C,

C(CH₃)₃), 25.70, 24.41 (2 t, 2CH₂). Anal. (C₃₀H₄₂N₆O₄) C, H, N.

Further purification of the mother liquors by chromatogra-

phy on silica gel (eluting with 2-2.5% MeOH/CH₂Cl₂) gave

(after base washing) additional 24 (11 mg, 9%).

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[[5-(4-me-

thylpiperazin-1-yl)pentyl]amino]-1,6-naphthyridin-2-yl]-

urea (25). Similar hydrolysis of crude 67 (170 mg) in MeOH

(45 mL) with NaOH (1.95 g, 48.8 mmol) and water (5 mL) at

0 °C for 2 h and then at 20 °C for 4 days and chromatography

of the resulting product on neutral alumina (eluting with 1%

EtOH/CHCl₃) gave (after base washing and crystallization) 25

(97 mg, 60% from alcohol 46): mp (CH₂Cl₂/hexane) 128-130

N⁷-[4-(Diethylamino)butyl]-3-(3,5-dimethoxyphenyl)-

1,6-naphthyridine-2,7-diamine (21). Similar hydrolysis of

69 (287 mg, 0.509 mmol) in dioxane (45 mL) with NaOH (4.01

g, 100 mmol) and water (5 mL) under N₂at 98 °C for 6 days

and chromatography of the resulting product on silica gel

(eluting with 4-7% MeOH/EtOAc containing 1% Et₃N) gave

(after base washing and crystallization) 21 (148 mg, 69%): mp

(CH₂Cl₂/hexane) 120-122.5 °C; ¹H NMR [(CD₃)₂SO] δ 8.45 (s,

1 H, H-5), 7.67 (s, 1 H, H-4), 6.59 (d, J ) 2.3 Hz, 2 H, H-2′,6′),

6.52 (t, J ) 2.2 Hz, 1 H, H-4′), 6.45 (br t, J ) 5.6 Hz, 1 H,

NHCH₂), 6.28 (br s, 2 H, NH₂), 6.18 (s, 1 H, H-8), 3.79 (s, 6 H,

2OCH₃), 3.21 (br td, J ) 6.5, 6.1 Hz, 2 H, NHCH₂), 2.43 (q, J

) 7.1 Hz, 4 H, N(CH₂)₂), 2.37 (t, J ) 7.1 Hz, 2 H, NCH₂), 1.56

(pentet, J ) 7.1 Hz, 2 H, CH₂), 1.46 (pentet, J ) 7.1 Hz, 2 H,

CH₂), 0.94 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 160.64 (s, 2

C, C-3′,5′), 159.08, 158.15 (2 s, C-2,7), 152.65 (s, C-8a), 150.33

(d, C-5), 139.55 (s, C-1′), 135.78 (d, C-4), 120.61 (s, C-3), 113.18

(s, C-4a), 106.49 (d, 2 C, C-2′,6′), 99.68 (d, C-4′), 93.71 (d, C-8),

55.17 (q, 2 C, 2OCH₃), 52.06 (t, NCH₂), 46.16 (t, 2 C, N(CH₂)₂),

41.49 (t, NCH₂), 26.84, 24.35 (2 t, 2CH₂), 11.68 (q, 2 C, 2CH₃).

Anal. (C₂₄H₃₃N₅O₂) C, H, N.

1

°C; H NMR [(CD₃)₂SO] δ 10.25 (br s, 1 H, NH), 8.69 (s, 1 H,

H-5), 7.98 (s, 1 H, H-4), 7.03 (br s, 1 H, NH), 6.90 (br t, J )

5.5 Hz, 1 H, NHCH₂), 6.63 (t, J ) 2.0 Hz, 1 H, H-4′), 6.62 (d,

J ) 2.0 Hz, 2 H, H-2′,6′), 6.38 (s, 1 H, H-8), 3.80 (s, 6 H,

2OCH₃), 3.28 (br td, J ) 6.6, 5.8 Hz, 2 H, NHCH₂), 2.6-2.0

(br s, 8 H, N(CH₂)₄N), 2.24 (t, J ) 7.2 Hz, 2 H, NCH₂), 2.12 (s,

3 H, NCH₃), 1.58 (pentet, J ) 7.1 Hz, 2 H, CH₂), 1.45 (pentet,

J ) 7.4 Hz, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃), 1.35 (m, 2 H,

CH₂); ¹³C NMR δ 161.11 (s, 2 C, C-3′,5′), 159.56 (s, C-7), 152.36,

152.02 (2 s, CONH, C-2), 151.34 (d, C-5), 149.32 (s, C-8a),

137.44 (d, C-4), 137.40 (s, C-1′), 120.98 (s, C-3), 113.07 (s, C-4a),

107.07 (d, 2 C, C-2′,6′), 100.16 (d, C-4′), 94.54 (br d, C-8), 57.81

(t, NCH₂), 55.39 (q, 2 C, 2OCH₃), 54.69, 52.66 (2 t, 2 × 2 C,

2N(CH₂)₂), 49.92 (s, C(CH₃)₃), 45.68 (q, NCH₃), 41.12 (t, NCH₂),

28.68 (t, CH₂), 28.65 (q, 3 C, C(CH₃)₃), 26.09, 24.46 (2 t, 2CH₂).

Anal. (C₃₁H₄₅N₇O₃) C, H, N.

Further base hydrolysis of the mother liquors followed by

chromatography of the resulting product on neutral alumina

(as above) and crystallization gave additional 25 (18 mg, 11%

from 46).

N-(tert-Butyl)-N′-[7-[[5-(diethylamino)pentyl]amino]-

3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-2-yl]urea (26).

Similar hydrolysis of 70 (137 mg, 0.237 mmol) in MeOH (45

Further purification of the mother liquors by chromatogra-

phy on alumina (eluting with 1-1.5% MeOH/CH₂Cl₂) gave

additional 21 (26 mg, 12%).

N-[3-(3,5-Dimethoxyphenyl)-7-[[3-(4-methyl-1-piper-

azinyl)propyl]amino]-1,6-naphthyridin-2-yl]-N′-ethy-

4644 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

lurea (16). A solution of 15 (106 mg, 0.243 mmol) in dry

DMSO (5 mL) was treated with 60% NaH (14 mg, 0.35 mmol).

Then the mixture was sealed under N₂(as above) and stirred

at 40-50 °C for 15 min and then at 20 °C for 20 min. A solution

of ethyl isocyanate (23 µL, 0.291 mmol) in dry DMSO (1 mL,

then 2 × 0.5 mL to rinse) was added (dropwise via syringe).

Then the mixture was stirred at 20 °C for 1 day. The resulting

mixture was cooled in ice, then treated with ice/aqueous

NaHCO₃(50 mL), adjusted to pH 10 with aqueous Na₂CO₃,

and extracted with CH₂Cl₂(8 × 50 mL). The extracts were

evaporated to dryness, and the residue was then chromato-

graphed on silica gel. Elution with 0-4% MeOH/EtOAc

containing 1% Et₃N gave foreruns. Then further elution with

6-9% MeOH/EtOAc containing 1% Et₃N gave (after base

washing) a crude oil (95 mg), which was further chromato-

graphed on silica gel. Elution with 0-1.5% MeOH/CH₂Cl₂

containing 1% Et₃N gave foreruns. Then further elution with

2% MeOH/CH₂Cl₂containing 1% Et₃N gave (after base wash-

ing and two recrystallizations from CH₂Cl₂/hexane) 16 (45 mg,

(br t, J ) 5.5 Hz, 1 H, NHCH₂), 6.62 (s, 3 H, H-2′,4′,6′), 6.54

(s, 1 H, H-8), 3.80 (s, 6 H, 2OCH₃), 3.30 (m, 4 H, 2NHCH₂),

2.44 (q, J ) 7.1 Hz, 4 H, N(CH₂)₂), 2.39 (t, J ) 7.1 Hz, 2 H,

NCH₂), 1.60 (pentet, J ) 7.0 Hz, 2 H, CH₂), 1.49 (pentet, J )

7.1 Hz, 2 H, CH₂), 1.19 (t, J ) 7.2 Hz, 3 H, CH₃), 0.94 (t, J )

7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 161.16 (s, 2 C, C-3′,5′), 159.63

(s, C-7), 153.50, 152.24 (2 s, CONH, C-2), 151.41 (d, C-5),

149.77 (s, C-8a), 137.57 (s + d, 2 C, C-4,1′), 120.98 (s, C-3),

113.29 (s, C-4a), 107.10 (d, 2 C, C-2′,6′), 100.19 (d, C-4′), 94.50

(br d, C-8), 55.43 (q, 2 C, 2OCH₃), 52.04 (t, NCH₂), 46.20 (t, 2

C, N(CH₂)₂), 41.47 (t, NHCH₂), 34.17 (t, CONHCH₂), 26.77,

24.28 (2 t, 2CH₂), 15.16 (q, CH₃), 11.67 (q, 2 C, 2CH₃). Anal.

(C₂₇H₃₈N₆O₃) C, H, N.

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[(3-hydrox-

ypropyl)amino]-1,6-naphthyridin-2-yl]urea (75). A solu-

tion of 13 (273 mg, 0.625 mmol) in dry DMF (10 mL) was

treated with 60% NaH (117 mg, 2.93 mmol). Then the mixture

was sealed under N₂(as above) and stirred at 20 °C for 15

min and then at 0 °C for 1.5 h. A solution of 3-iodopropyl

benzoate⁵⁴(246 mg, 0.848 mmol) in dry DMF (1 mL, then 1

mL to rinse) was added (syringe), and the mixture was foil-

covered and stirred at 0-20 °C for 1 day. The resulting solution

was cooled in ice, then treated with ice/aqueous NaHCO₃(100

mL), and extracted with EtOAc (5 × 150 mL). The extracts

were evaporated to dryness, and the residue was then chro-

matographed on silica gel. Elution with 0-0.6% MeOH/CH₂-

Cl₂gave foreruns. Then further elution with 0.6% MeOH/

CH₂Cl₂gave 3-[[2-[[(tert-butylamino)carbonyl]amino]-3-(3,5-

dimethoxyphenyl)-1,6-naphthyridin-7-yl]amino]propyl benzoate

1

37%): mp (CH₂Cl₂/hexane) 170-171 °C; H NMR [(CD₃)₂SO]

δ 9.91 (br t, J ) 5.5 Hz, 1 H, CONHCH₂), 8.69 (s, 1 H, H-5),

7.99 (s, 1 H, H-4), 7.20 (br s, 1 H, NH), 6.87 (br t, J ) 5.6 Hz,

1 H, NHCH₂), 6.63 (s, 3 H, H-2′,4′,6′), 6.53 (s, 1 H, H-8), 3.80

(s, 6 H, 2OCH₃), 3.31 (m, 4 H, 2NHCH₂), 2.6-2.1 (br s, 8 H,

N(CH₂)₄N), 2.38 (t, J ) 7.0 Hz, 2 H, NCH₂), 2.15 (s, 3 H, NCH₃),

1.74 (pentet, J ) 6.8 Hz, 2 H, CH₂), 1.19 (t, J ) 7.2 Hz, 3 H,

CH₃); ¹³C NMR δ 161.10 (s, 2 C, C-3′,5′), 159.57 (s, C-7), 153.38,

152.19 (2 s, CONH, C-2), 151.35 (d, C-5), 149.72 (s, C-8a),

137.51 (s + d, 2 C, C-4,1′), 120.98 (s, C-3), 113.26 (s, C-4a),

107.05 (d, 2 C, C-2′,6′), 100.15 (d, C-4′), 94.46 (br d, C-8), 55.62

(t, NCH₂), 55.38 (q, 2 C, 2OCH₃), 54.73, 52.71 (2 t, 2 × 2 C,

2N(CH₂)₂), 45.68 (q, NCH₃), 39.93 (t, NHCH₂), 34.10 (t,

CONHCH₂), 25.91 (t, CH₂), 15.14 (q, CH₃). Anal. (C₂₇H₃₇N₇O₃)-

C, H, N.

Further purification of the mother liquors by preparative

reversed-phase C-18 HPLC (47.5% CH₃CN/aqueous HCO₂NH₄

buffer, pH 3.45) gave two fractions, which were each basified

(to pH 10) with aqueous Na₂CO₃(50 mL), concentrated under

reduced pressure (to remove CH₃CN), and extracted with CH₂-

Cl₂(4 × 50 mL) to give firstly additional 16 (12 mg, 10%) and

secondly (2Z)-3-(3,5-dimethoxyphenyl)-N-ethyl-2-[[(Z)-(ethy-

lamino)(oxo)methyl]imino]-7-[[3-(4-methyl-1-piperazinyl)pro-

pyl]amino]-1,6-naphthyridine-1(2H)-carboxamide (78) (10 mg,

7%) as an oil: ¹H NMR [(CD₃)₂SO] δ 14.12, 9.78 (2 br s, 2 × 1

H, 2CONHCH₂), 8.58 (br s, 1 H, H-5), 8.04 (s, 1 H, H-4), 7.28

(br s, 1 H, NHCH₂), 6.65 (d, J ) 2.3 Hz, 2 H, H-2′,6′), 6.57 (br

s, 1 H, H-8), 6.55 (t, J ) 2.1 Hz, 1 H, H-4′), 3.78 (m, 2 H,

CONHCH₂), 3.77 (s, 6 H, 2OCH₃), 3.30 (m, 2 H, NHCH₂), 2.80

(br s, 2 H, CONHCH₂), 2.6-2.0 (br s, 8 H, N(CH₂)₄N), 2.35 (t,

J ) 6.9 Hz, 2 H, NCH₂), 2.15 (s, 3 H, NCH₃), 1.72 (pentet, J )

6.9 Hz, 2 H, CH₂), 1.03 (t, J ) 6.8 Hz, 3 H, CH₃), 0.72 (br s, 3

H, CH₃); ¹³C NMR δ 162.53 (br s, CONH), 160.22 (s, 2 C,

C-3′,5′), 159.88 (br s, C-7), 156.82 (br s, C-2), 154.20 (br s,

CONH), 150.99 (d, C-5), 141.74 (br s, C-8a), 139.03 (d + s,

C-4,1′), 126.82 (s, C-3), 110.44 (br s, C-4a), 107.38 (d, 2 C,

C-2′,6′), 99.32 (d, C-4′), 87.69 (br d, C-8), 55.40 (t, NCH₂), 55.17

(q, 2 C, 2OCH₃), 54.70, 52.66 (2 t, 2 × 2 C, 2N(CH₂)₂), 45.63

(q, NCH₃), 39.65 (t, NHCH₂), 38.80 (t, CONHCH₂), 34.06 (br

t, CONHCH₂), 25.82 (t, CH₂), 14.93, 14.15 (2 q, 2CH₃);

HRFABMS calcd for C₃₀H₄₃N₈O₄m/z (MH⁺) 579.3407, found

579.3399.

1

(74) (23 mg, 7%): mp (CH₂Cl₂/hexane) 165-167 °C; H NMR

[(CD₃)₂SO] δ 10.20 (br s, 1 H, NH), 8.69 (s, 1 H, H-5), 7.98 (s,

1 H, H-4), 7.98 (dt, J ) 7.0, 1.4 Hz, 2 H, H-2′′,6′′), 7.66 (tt, J

) 7.5, 1.2 Hz, 1 H, H-4′′), 7.53 (t, J ) 7.7 Hz, 2 H, H-3′′,5′′),

7.03 (br t, J ) 5.7 Hz, 1 H, NHCH₂), 7.02 (br s, 1 H, NH), 6.63

(t, J ) 1.7 Hz, 1 H, H-4′), 6.62 (d, J ) 1.8 Hz, 2 H, H-2′,6′),

6.43 (s, 1 H, H-8), 4.39 (t, J ) 6.3 Hz, 2 H, OCH₂), 3.80 (s, 6

H, 2OCH₃), 3.49 (br td, J ) 6.4, 5.8 Hz, 2 H, NHCH₂), 2.05

(pentet, J ) 6.5 Hz, 2 H, CH₂), 1.38 (s, 9 H, C(CH₃)₃); ¹³C NMR

δ 165.70 (s, CdO), 161.11 (s, 2 C, C-3′,5′), 159.43 (s, C-7),

152.39, 151.98 (2 s, CONH, C-2), 151.32 (d, C-5), 149.29 (s,

C-8a), 137.42 (d, C-4), 137.36 (s, C-1′), 133.16 (d, C-4′′), 129.76

(s, C-1′′), 129.03, 128.63 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′), 121.20

(s, C-3), 113.20 (s, C-4a), 107.07 (d, 2 C, C-2′,6′), 100.20 (d,

C-4′), 95.06 (br d, C-8), 62.71 (t, OCH₂), 55.39 (q, 2 C, 2OCH₃),

49.90 (s, C(CH₃)₃), 37.99 (t, NCH₂), 28.62 (q, 3 C, C(CH₃)₃),

28.07 (t, CH₂). Anal. (C₃₁H₃₅N₅O₅) C, H, N.

Further elution with 0.6-1% MeOH/CH₂Cl₂gave (after

crystallization twice) recovered 13 (87 mg, 32%).

Further elution with 1.4-1.6% MeOH/CH₂Cl₂gave (after

crystallization) the desired 75 (92 mg, 33%): mp (Et₂O/hexane)

133-138 °C; ¹H NMR [(CD₃)₂SO] δ 10.22 (br s, 1 H, NH), 8.69

(s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.02 (br s, 1 H, NH), 6.85 (br

t, J ) 5.5 Hz, 1 H, NHCH₂), 6.62 (s, 3 H, H-2′,4′,6′), 6.41 (s, 1

H, H-8), 4.50 (br t, J ) 5.1 Hz, 1 H, CH₂OH), 3.80 (s, 6 H,

2OCH₃), 3.52 (td, J ) 6.0, 5.6 Hz, 2 H, CH₂OH), 3.33 (m, 2 H,

NHCH₂), 1.74 (pentet, J ) 6.5 Hz, 2 H, CH₂), 1.40 (s, 9 H,

C(CH₃)₃); ¹³C NMR δ 161.11 (s, 2 C, C-3′,5′), 159.60 (s, C-7),

152.37, 152.02 (2 s, CONH, C-2), 151.32 (d, C-5), 149.38 (s,

C-8a), 137.42 (d, C-4), 137.39 (s, C-1′), 121.03 (s, C-3), 113.11

(s, C-4a), 107.08 (d, 2 C, C-2′,6′), 100.18 (d, C-4′), 94.45 (br d,

C-8), 58.53 (t, OCH₂), 55.39 (q, 2 C, 2OCH₃), 49.93 (s, C(CH₃)₃),

38.35 (t, NCH₂), 32.05 (t, CH₂), 28.65 (q, 3 C, C(CH₃)₃). Anal.

(C₂₄H₃₁N₅O₄) C, H, N.

N-[7-[[4-(Diethylamino)butyl]amino]-3-(3,5-dimethox-

yphenyl)-1,6-naphthyridin-2-yl]-N′-ethylurea (22). Simi-

lar reaction of 21 (103 mg, 0.243 mmol) in dry DMSO (5 mL)

with 60% NaH (14 mg, 0.35 mmol) under N₂at 40-50 °C for

15 min, and then at 20 °C for 15 min, followed by reaction

with a solution of ethyl isocyanate (23 µL, 0.291 mmol) in dry

DMSO (1 mL, then 2 × 0.5 mL) at 20 °C for 1 day and

chromatography of the resulting product on silica gel (eluting

with 0.5-0.75% MeOH/CH₂Cl₂containing 0.5% Et₃N) gave

(after base washing and two recrystallizations from CH₂Cl₂/

hexane) 22 (93 mg, 77%): mp (CH₂Cl₂/hexane) 145-146.5 °C;

¹H NMR [(CD₃)₂SO] δ 9.94 (br t, J ) 5.5 Hz, 1 H, CONHCH₂),

8.69 (s, 1 H, H-5), 7.99 (s, 1 H, H-4), 7.22 (br s, 1 H, NH), 6.86

Further purification of the mother liquors by chromatogra-

phy on silica gel (eluting with 1.25-1.5% MeOH/CH₂Cl₂) gave

(after crystallization) additional 75 (21 mg, 7%).

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[(4-hydrox-

ybutyl)amino]-1,6-naphthyridin-2-yl]urea (76). A solution

of 42 (236 mg, 0.424 mmol) in absolute EtOH (190 mL) was

hydrogenated over 5% Pd/C (566 mg) at 60 psi and 20 °C for

48 h. The resulting solution was Celite filtered, washing with

25% MeOH/CH₂Cl₂. Then the Celite and catalyst were further

extracted by stirring in refluxing 25% MeOH/CH₂Cl₂for 10

min and then refiltering and washing as before. The

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4645

filtrates were then combined, the solvents were removed, and

the residue was chromatographed on silica gel. Elution with

0-0.5% MeOH/CH₂Cl₂gave foreruns. Then further elution

with 0.5-0.75% MeOH/CH₂Cl₂gave recovered 42 (176 mg,

75%). Elution with 1-1.5% MeOH/CH₂Cl₂gave minor impuri-

ties. Then elution with 1.5-2% MeOH/CH₂Cl₂gave a crude

oil (32 mg, <16%), which was combined with similar material

from subsequent repeat runs and crystallized to give 76 (42

mg, 21% overall): mp (CH₂Cl₂/hexane) 156-157.5 °C; ¹H NMR

[(CD₃)₂SO] δ 10.24 (br s, 1 H, NH), 8.69 (s, 1 H, H-5), 7.98 (s,

1 H, H-4), 7.02 (br s, 1 H, NH), 6.90 (br t, J ) 5.6 Hz, 1 H,

NHCH₂), 6.62 (m, 3 H, H-2′,4′,6′), 6.39 (s, 1 H, H-8), 4.43 (br

t, J ) 5.1 Hz, 1 H, CH₂OH), 3.80 (s, 6 H, 2OCH₃), 3.44 (td, J

) 6.2, 5.5 Hz, 2 H, CH₂OH), 3.29 (br q, J ) 6.4 Hz, 2 H,

NHCH₂), 1.61 (pentet, J ) 7.0 Hz, 2 H, CH₂), 1.52 (pentet, J

) 6.7 Hz, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 161.14

(s, 2 C, C-3′,5′), 159.59 (s, C-7), 152.39, 152.06 (2 s, CONH,

C-2), 151.37 (d, C-5), 149.36 (s, C-8a), 137.46 (d, C-4), 137.42

(s, C-1′), 121.03 (s, C-3), 113.10 (s, C-4a), 107.10 (d, 2 C, C-2′,6′),

100.20 (d, C-4′), 94.65 (br d, C-8), 60.50 (t, OCH₂), 55.42 (q, 2

C, 2OCH₃), 49.96 (s, C(CH₃)₃), 41.15 (t, NCH₂), 30.04 (t, CH₂),

28.67 (q, 3 C, C(CH₃)₃), 25.46 (t, CH₂). Anal. (C₂₅H₃₃N₅O₄‚

0.5H₂O) C, H, N.

2 × 3 C, 2C(CH₃)₃); HRFABMS calcd for C₂₄H₃₁N₆O₂m/z (MH⁺)

435.2509, found 435.2496.

Further elution with 33-50% EtOAc/light petroleum gave

80⁴¹(1.89 g, 88%).

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-phenyl-1,6-

naphthyridin-7-yl]acetamide (82). A solution of 80 (1.88

g, 5.61 mmol) in pyridine (45 mL) was treated (dropwise) with

Ac₂O (5.3 mL, 56.2 mmol), and the mixture was then stirred

at 20 °C for 10 h. The resulting solution was cooled in ice and

then added slowly to a stirred mixture of ice and aqueous

NaHCO₃, keeping the pH at 8 with excess NaHCO₃. The

resulting suspension was extracted with CH₂Cl₂(5 × 200 mL).

Then the combined extracts were evaporated to dryness and

the residue was crystallized directly (from warm CH₂Cl₂/light

petroleum) to give 82 (1.94 g, 92%): mp 194.5-196 °C dec; ¹H

NMR [(CD₃)₂SO] δ 10.75, 10.14 (2 br s, 2 × 1 H, 2NH), 8.98

(s, 1 H, H-5), 8.34, 8.22 (2 s, 2 × 1 H, H-4,8), 7.61 (t, J ) 7.2

Hz, 2 H, H-3′,5′), 7.56 (m, 3 H, H-2′,4′,6′), 7.12 (br s, 1 H, NH),

2.16 (s, 3 H, COCH₃), 1.41 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 169.41

(s, CONH), 152.95, 151.73, 151.45 (3 s, CONH, C-2,7), 150.66

(d, C-5), 148.95 (s, C-8a), 137.31 (d, C-4), 134.93 (s, C-1′),

129.48, 129.06 (2 d, 2 × 2 C, C-2′,3′,5′,6′), 128.95 (d, C-4′),

125.19 (s, C-3), 117.09 (s, C-4a), 105.09 (d, C-8), 50.05 (s,

C(CH₃)₃), 28.55 (q, 3 C, C(CH₃)₃), 23.92 (q, CH₃). Anal.

(C₂₁H₂₃N₅O₂) C, H, N.

N-[3-(Benzyloxy)propyl]-N-[2-[[(tert-butylamino)car-

bonyl]amino]-3-phenyl-1,6-naphthyridin-7-yl]aceta-

mide (85). A solution of 82 (1.05 g, 2.79 mmol) in dry DMF

(50 mL) was treated with 60% NaH (489 mg, 12.2 mmol). Then

the mixture was sealed under N₂and stirred at 20 °C for 30

min and then at 0 °C for 1 h. A solution of benzyl 3-iodopropyl

ether⁴³(1.00 g, 3.62 mmol) in dry DMF (5 mL, then 2 × 5 mL

to rinse) was then added (syringe), and the mixture was foil-

covered and stirred at 0-20 °C for 2.5 days. The resulting

solution was cooled in ice, then treated with ice/aqueous

NaHCO₃(300 mL) and extracted with EtOAc (5 × 200 mL).

The combined extracts were evaporated to dryness, and the

residue was then chromatographed on silica gel. Elution with

0-0.4% MeOH/CH₂Cl₂gave foreruns. Then further elution

with 0.5-0.75% MeOH/CH₂Cl₂yielded crude material which,

upon crystallization twice from CH₂Cl₂/hexane, gave N-[7-[[3-

(benzyloxy)propyl]amino]-3-phenyl-1,6-naphthyridin-2-yl]-N′-

tert-butylurea (83) (151 mg, 11%): mp (CH₂Cl₂/hexane) 149-

150.5 °C; ¹H NMR [(CD₃)₂SO] δ 10.24 (br s, 1 H, NH), 8.71 (s,

1 H, H-5), 7.98 (s, 1 H, H-4), 7.58 (t, J ) 7.2 Hz, 2 H, H-3′,5′),

7.51 (m, 3 H, H-2′,4′,6′), 7.31 (m, 5 H, H-2′′,3′′,4′′,5′′,6′′), 6.92

(br t, J ) 5.7 Hz, 1 H, NHCH₂), 6.92 (br s, 1 H, NH), 6.41 (s,

1 H, H-8), 4.48 (s, 2 H, OCH₂Ph), 3.56 (t, J ) 6.2 Hz, 2 H,

OCH₂), 3.38 (m, 2 H, NHCH₂), 1.87 (pentet, J ) 6.5 Hz, 2 H,

CH₂), 1.39 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 159.53 (s, C-7), 152.52,

152.03 (2 s, CONH, C-2), 151.40 (d, C-5), 149.38 (s, C-8a),

138.58 (s, C-1′′), 137.77 (d, C-4), 135.50 (s, C-1′), 129.44, 129.11

(2 d, 2 × 2 C, C-2′,3′,5′,6′), 128.54 (d, C-4′), 128.16, 127.34 (2

d, 2 × 2 C, C-2′′,3′′,5′′,6′′), 127.28 (d, C-4′′), 121.23 (s, C-3),

113.34 (s, C-4a), 94.65 (br d, C-8), 71.87 (t, OCH₂Ph), 67.52 (t,

OCH₂), 49.95 (s, C(CH₃)₃), 38.52 (t, NCH₂), 29.07 (t, CH₂), 28.64

(q, 3 C, C(CH₃)₃). Anal. (C₂₉H₃₃N₅O₂) C, H, N.

N-(tert-Butyl)-N′-[3-(3,5-dimethoxyphenyl)-7-[(5-hydrox-

ypentyl)amino]-1,6-naphthyridin-2-yl]urea (77). A stirred

solution of 46 (92 mg, 0.176 mmol) in MeOH (27 mL) at 0 °C

was treated with NaOH (1.04 g, 26.0 mmol) and water (3 mL,

added dropwise). Then the mixture was stirred at 0 °C for 1 h

and then at 20 °C for 7 days. A solution of excess NaHCO₃in

ice/water (100 mL) was then added, and the mixture was

extracted with CH₂Cl₂(4 × 100 mL). The combined extracts

were evaporated to dryness and the residue was then chro-

matographed on silica gel. Elution with 0-1.4% MeOH/CH₂-

Cl₂gave foreruns. Then further elution with 1.5% MeOH/

CH₂Cl₂gave 77 (77 mg, 84%): mp (CH₂Cl₂/hexane) 151-153

1

°C; H NMR [(CD₃)₂SO] δ 10.24 (br s, 1 H, NH), 8.69 (s, 1 H,

H-5), 7.98 (s, 1 H, H-4), 7.02 (br s, 1 H, NH), 6.91 (br t, J )

5.6 Hz, 1 H, NHCH₂), 6.63 (t, J ) 2.1 Hz, 1 H, H-4′), 6.62 (d,

J ) 1.9 Hz, 2 H, H-2′,6′), 6.38 (s, 1 H, H-8), 4.36 (br t, J ) 5.1

Hz, 1 H, CH₂OH), 3.80 (s, 6 H, 2OCH₃), 3.40 (td, J ) 6.3, 5.3

Hz, 2 H, CH₂OH), 3.28 (br td, J ) 7.1, 5.6 Hz, 2 H, NHCH₂),

1.58 (pentet, J ) 7.1 Hz, 2 H, CH₂), 1.47 (pentet, J ) 6.6 Hz,

2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃), 1.38 (m, 2 H, CH₂); ¹³C NMR

δ 161.11 (s, 2 C, C-3′,5′), 159.56 (s, C-7), 152.37, 152.02 (2 s,

CONH, C-2), 151.34 (d, C-5), 149.32 (s, C-8a), 137.43 (d, C-4),

137.40 (s, C-1′), 120.99 (s, C-3), 113.06 (s, C-4a), 107.08 (d, 2

C, C-2′,6′), 100.17 (d, C-4′), 94.53 (br d, C-8), 60.59 (t, OCH₂),

55.39 (q, 2 C, 2OCH₃), 49.92 (s, C(CH₃)₃), 41.22 (t, NCH₂), 32.26

(t, CH₂), 28.65 (t, CH₂), 28.64 (q, 3 C, C(CH₃)₃), 23.08 (t, CH₂).

Anal. (C₂₆H₃₅N₅O₄) C, H, N.

N-(7-Amino-3-phenyl-1,6-naphthyridin-2-yl)-N′-tert-bu-

tylurea (80). A solution of 3-phenyl-1,6-naphthyridine-2,7-

diamine⁴²(1.50 g, 6.36 mmol) in dry DMF (25 mL) was treated

with 60% NaH (0.32 g, 8.03 mmol). Then the mixture was

sealed under N₂(as above) and stirred at 20 °C for 20 min

and then at 0 °C for 1 h. tert-Butyl isocyanate (0.907 mL, 7.95

mmol) was added (dropwise via syringe), and then the mixture

was stirred at 20 °C for 1 day. The resulting mixture was

cooled in ice, then treated with ice/aqueous NaHCO₃(170 mL)

and extracted with EtOAc (10 × 150 mL). The extracts were

evaporated to dryness, and the residue was then chromato-

graphed on silica gel. Elution with 25% EtOAc/light petroleum

gave firstly N-(tert-butyl)-N′-[7-(3-tert-butylureido)-3-phenyl-

1,6-naphthyridin-2-yl]urea (81) (56 mg, 2%): mp (CH₂Cl₂/

hexane) 216 °C dec; ¹H NMR [(CD₃)₂SO] δ 10.11, 9.05 (2 br s,

2 × 1 H, 2NH), 8.88 (s, 1 H, H-5), 8.16 (s, 1 H, H-4), 7.83 (s, 1

H, H-8), 7.60 (t, J ) 7.2 Hz, 2 H, H-3′,5′), 7.55 (m, 3 H,

H-2′,4′,6′), 7.29, 7.07 (2 br s, 2 × 1 H, 2 NH), 1.41, 1.34 (2 s, 2

× 9 H, 2C(CH₃)₃); ¹³C NMR δ 153.46, 153.08, 152.94, 151.77

(4 s, 2CONH,C-2,7), 150.41 (d, C-5), 149.09 (s, C-8a), 137.50

(d, C-4), 135.05 (s, C-1′), 129.47, 129.09 (2 d, 2 × 2 C,

C-2′,3′,5′,6′), 128.86 (d, C-4′), 124.27 (s, C-3), 115.89 (s, C-4a),

102.06 (d, C-8), 50.05, 49.52 (2 s, 2C(CH₃)₃), 28.88, 28.64 (2 q,

Further elution with 0.75-0.8% MeOH/CH₂Cl₂gave crude

recovered 82 (0.23 g). Then further elution with 0.8-1%

MeOH/CH₂Cl₂gave 85 (918 mg, 63%): mp (EtOAc/hexane)

62-66 °C; ¹H NMR [(CD₃)₂SO] δ 9.88 (br s, 1 H, NH), 9.13 (s,

1 H, H-5), 8.33 (s, 1 H, H-4), 7.69 (s, 1 H, H-8), 7.63 (tt, J )

7.0, 1.5 Hz, 2 H, H-3′,5′), 7.58 (m, 3 H, H-2′,4′,6′), 7.26 (m, 6

H, NH, H-2′′,3′′,4′′,5′′,6′′), 4.35 (s, 2 H, OCH₂Ph), 3.96 (t, J )

7.1 Hz, 2 H, NCH₂), 3.46 (t, J ) 6.1 Hz, 2 H, OCH₂), 1.99 (s,

3 H, COCH₃), 1.80 (pentet, J ) 6.6 Hz, 2 H, CH₂), 1.41 (s, 9 H,

C(CH₃)₃); ¹³C NMR δ 169.50 (s, CdO), 154.37, 153.15, 151.60

(3 s, CONH, C-2,7), 151.33 (d, C-5), 148.85 (s, C-8a), 138.39

(s, C-1′′), 137.34 (d, C-4), 134.76 (s, C-1′), 129.58 (d, 2 C, C-3′,5′),

129.20 (d, C-4′), 129.02 (d, 2 C, C-2′,6′), 128.08, 127.23 (2 d, 2

× 2 C, C-2′′,3′′,5′′,6′′), 127.21 (d + s, C-3,4′′), 118.79 (s, C-4a),

115.59 (d, C-8), 71.73 (t, OCH₂Ph), 67.10 (t, OCH₂), 50.21 (s,

C(CH₃)₃), 44.83 (t, NCH₂), 28.67 (q, 3 C, C(CH₃)₃), 28.16 (t,

CH₂), 22.97 (q, CH₃). Anal. (C₃₁H₃₅N₅O₃) C, H, N.

4646 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

N-[4-(Benzyloxy)butyl]-N-[2-[[(tert-butylamino)carbo-

nyl]amino]-3-phenyl-1,6-naphthyridin-7-yl]acetamide (86).

Similar reaction of a stirred solution of 82 (0.99 g, 2.63 mmol)

in dry DMF (50 mL) with 60% NaH (468 mg, 11.7 mmol) under

N₂at 20 °C for 30 min and then at 0 °C for 1 h followed by

reaction with benzyl 4-iodobutyl ether⁴⁴(1.00 g, 3.45 mmol)

in dry DMF (5 mL, then 2 × 5 mL) at 0-20 °C for 2.5 days

and chromatography of the resulting product on silica gel

(eluting with 0.4-0.6% MeOH/CH₂Cl₂) gave (after crystalliza-

tion from Et₂O/hexane, then twice from CH₂Cl₂/hexane) N-[7-

[[4-(benzyloxy)butyl]amino]-3-phenyl-1,6-naphthyridin-2-yl]-

N′-tert-butylurea (84) (53 mg, 4%): mp (CH₂Cl₂/hexane) 107-

108.5 °C; ¹H NMR [(CD₃)₂SO] δ 10.24 (br s, 1 H, NH), 8.70 (s,

1 H, H-5), 7.97 (s, 1 H, H-4), 7.58 (t, J ) 7.2 Hz, 2 H, H-3′,5′),

7.51 (m, 3 H, H-2′,4′,6′), 7.29 (m, 5 H, H-2′′,3′′,4′′,5′′,6′′), 6.93

(br t, J ) 5.5 Hz, 1 H, NHCH₂), 6.91 (br s, 1 H, NH), 6.40 (s,

1 H, H-8), 4.46 (s, 2 H, OCH₂Ph), 3.48 (t, J ) 5.8 Hz, 2 H,

OCH₂), 3.31 (m, 2 H, NHCH₂), 1.65 (m, 4 H, 2CH₂), 1.39 (s, 9

H, C(CH₃)₃); ¹³C NMR δ 159.58 (s, C-7), 152.53, 152.09 (2 s,

CONH, C-2), 151.42 (d, C-5), 149.39 (s, C-8a), 138.66 (s, C-1′′),

137.80 (d, C-4), 135.53 (s, C-1′), 129.48, 129.13 (2 d, 2 × 2 C,

C-2′,3′,5′,6′), 128.56 (d, C-4′), 128.18, 127.34 (2 d, 2 × 2 C,

C-2′′,3′′,5′′,6′′), 127.28 (d, C-4′′), 121.20 (s, C-3), 113.32 (s, C-4a),

94.72 (br d, C-8), 71.76 (t, OCH₂Ph), 69.44 (t, OCH₂), 49.99 (s,

C(CH₃)₃), 41.06 (t, NCH₂), 28.66 (q, 3 C, C(CH₃)₃), 26.82, 25.67

(2 t, 2CH₂). Anal. (C₃₀H₃₅N₅O₂) C, H, N.

Further elution with 0.6-0.75% MeOH/CH₂Cl₂gave crude

recovered 82 (0.15 g), and then further elution with 0.75-2%

MeOH/CH₂Cl₂gave 86 (1.06 g, 75%): foam; ¹H NMR [(CD₃)₂-

SO] δ 9.88 (br s, 1 H, NH), 9.14 (s, 1 H, H-5), 8.35 (s, 1 H,

H-4), 7.69 (s, 1 H, H-8), 7.63 (tt, J ) 7.0, 1.5 Hz, 2 H, H-3′,5′),

7.58 (m, 3 H, H-2′,4′,6′), 7.25 (m, 6 H, NH, H-2′′,3′′,4′′,5′′,6′′),

4.39 (s, 2 H, OCH₂Ph), 3.90 (m, 2 H, NCH₂), 3.39 (m, 2 H,

OCH₂), 1.98 (s, 3 H, COCH₃), 1.55 (m, 4 H, 2CH₂), 1.40 (s, 9

H, C(CH₃)₃); ¹³C NMR δ 169.29 (s, CdO), 154.19, 153.14,

151.53 (3 s, CONH, C-2,7), 151.33 (d, C-5), 148.80 (s, C-8a),

138.52 (s, C-1′′), 137.32 (d, C-4), 134.73 (s, C-1′), 129.52 (d, 2

C, C-3′,5′), 129.14 (d, C-4′), 128.98 (d, 2 C, C-2′,6′), 128.05,

127.19 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′), 127.16 (d + s, C-3,4′′),

118.74 (s, C-4a), 115.58 (d, C-8), 71.62 (t, OCH₂Ph), 69.14 (t,

OCH₂), 50.15 (s, C(CH₃)₃), 46.77 (t, NCH₂), 28.61 (q, 3 C,

C(CH₃)₃), 26.39, 24.60 (2 t, 2CH₂), 22.94 (q, CH₃). Anal.

(C₃₂H₃₇N₅O₃) C, H, N.

gave crude N-[2-[[(tert-butylamino)carbonyl]amino]-3-phenyl-

1,6-naphthyridin-7-yl]-N-(4-hydroxybutyl)acetamide (88) (2.4

mg, 11%) as an oil (see below).

Further elution of the column with 2.5-3% MeOH/CH₂Cl₂

gave a minor component, and then further elution with 3%

MeOH/CH₂Cl₂gave crude N-[2-[[(tert-butylamino)carbonyl]-

amino]-3-phenyl-3,4-dihydro-1,6-naphthyridin-7-yl]-N-(4-hy-

droxybutyl)acetamide (90) (5 mg, 23%) as an oil: ¹H NMR

[(CD₃)₂SO] δ 9.92 (br s, 1 H, NH), 9.81 (br s, 1 H, NH), 8.09 (s,

1 H, H-5), 7.25 (t, J ) 7.1 Hz, 2 H, H-3′,5′), 7.20 (t, J ) 7.1 Hz,

1 H, H-4′), 7.05 (d, J ) 7.2 Hz, 2 H, H-2′,6′), 7.03 (s, 1 H, H-8),

4.34 (br t, J ) 5.1 Hz, 1 H, CH₂OH), 4.07 (br d, J ) 6.1 Hz, 1

H, H-3), 3.71 (m, 2 H, NCH₂), 3.33 (m, 2 H, OCH₂), 3.25 (br

dd, J ) 16.4, 6.7 Hz, 1 H, H-4), 2.99 (br d, J ) 16.0 Hz, 1 H,

H-4), 1.87 (s, 3 H, COCH₃), 1.41 (m, 2 H, CH₂), 1.37 (s, 9 H,

C(CH₃)₃), 1.35 (m, 2 H, CH₂); HRFABMS calcd for C₂₅H₃₄N₅O₃

m/z (MH⁺) 452.2662, found 452.2664.

B. By Reaction with BF₃‚Et₂O/EtSH. A solution of 86

(10.5 mg, 19.5 µmol) in CH₂Cl₂(1 mL) was treated with EtSH

(85 µL, 1.15 mmol), followed by BF₃‚Et₂O (20 µL, 0.158 mmol).

Then the mixture was stirred at 20 °C for 2 days. A solution

of aqueous NaHCO₃/Na₂CO₃(50 mL) was then added, and the

mixture was extracted with CH₂Cl₂(4 × 50 mL). The combined

extracts were evaporated to dryness, and the residue was then

chromatographed on silica gel. Elution with 0-1.75% MeOH/

CH₂Cl₂gave foreruns. Then further elution with 2-2.5%

MeOH/CH₂Cl₂gave crude 88 (5.3 mg, 61%) as an oil (see

below).

Further elution with 3-5% MeOH/CH₂Cl₂gave N-[2-[(ami-

nocarbonyl)amino]-3-phenyl-1,6-naphthyridin-7-yl]-N-(4-hy-

droxybutyl)acetamide (91) (3.0 mg, 39%): mp (MeOH/CH₂Cl₂/

hexane) 165-167 °C; ¹H NMR [(CD₃)₂SO] δ 9.14 (s, 1 H, H-5),

9.12 (br s, 1 H, NH), 8.35 (s, 1 H, H-4), 7.91 (s, 1 H, H-8), 7.63

(t, J ) 7.2 Hz, 2 H, H-3′,5′), 7.58 (m, 3 H, H-2′,4′,6′), 7.55, 7.28

(2 br s, 2 × 1 H, 2NH), 4.35 (br t, J ) 5.1 Hz, 1 H, CH₂OH),

3.87 (t, J ) 7.2 Hz, 2 H, NCH₂), 3.36 (m, 2 H, OCH₂), 1.98 (s,

3 H, COCH₃), 1.48 (pentet, J ) 7.3 Hz, 2 H, CH₂), 1.39 (pentet,

J ) 7.1 Hz, 2 H, CH₂); ¹³C NMR δ 169.17 (s, CdO), 154.02,

153.76, 152.87 (3 s, CONH, C-2,7), 151.31 (d, C-5), 149.23 (s,

C-8a), 137.35 (d, C-4), 134.93 (s, C-1′), 129.52 (d, 2 C, C-3′,5′),

129.10 (d, C-4′), 129.01 (d, 2 C, C-2′,6′), 127.14 (s, C-3), 118.85

(s, C-4a), 116.14 (d, C-8), 60.30 (t, OCH₂), 46.71 (t, NCH₂),

29.68 (t, CH₂), 24.42 (t, CH₂), 22.89 (q, CH₃). Anal. (C₂₁H₂₃N₅O₃‚

0.25H₂O) C, H, N.

Debenzylation of 86. A. By Hydrogenation. A solution

of 86 (25.6 mg, 47.5 µmol) in absolute EtOH (20 mL) was

hydrogenated over 5% Pd/C (30 mg) at 60 psi and 20 °C for 48

h. The resulting solution was Celite filtered, washing with 25%

MeOH/CH₂Cl₂. Then the Celite and catalyst were further

extracted by stirring in refluxing 25% MeOH/CH₂Cl₂for 10

min and then refiltering and washing as before. The filtrates

were then combined, the solvents were removed, and the

residue was chromatographed on silica gel. Elution with 0-1%

MeOH/CH₂Cl₂gave foreruns. Then further elution with 1.25%

MeOH/CH₂Cl₂gave recovered 86 (2.2 mg, 9%). Elution with

1.5% MeOH/CH₂Cl₂gave N-[4-(benzyloxy)butyl]-N-[2-[[(tert-

butylamino)carbonyl]amino]-3-phenyl-3,4-dihydro-1,6-naph-

thyridin-7-yl]acetamide (89) (10 mg, 39%): mp (EtOAc/hexane)

106-108 °C; ¹H NMR [(CD₃)₂SO] δ 9.93 (br s, 1 H, NH),

9.82 (br s, 1 H, NH), 8.08 (s, 1 H, H-5), 7.24 (m, 8 H,

H-3′,4′,5′,2′′,3′′,4′′,5′′,6′′), 7.04 (m, 3 H, H-2′,6′,8), 4.39 (s, 2 H,

OCH₂Ph), 4.07 (br d, J ) 6.6 Hz, 1 H, H-3), 3.72 (m, 2 H,

NCH₂), 3.35 (m, 2 H, OCH₂), 3.28 (m, 1 H, H-4), 3.00 (br d, J

) 16.0 Hz, 1 H, H-4), 1.87 (s, 3 H, COCH₃), 1.48 (m, 4 H, 2CH₂),

1.36 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 169.02 (s, CdO), 163.21 (s,

C-2), 155.03 (s, C-7), 152.36 (s, CONH), 151.68 (s, C-8a), 147.28

(d, C-5), 138.55 (s, C-1′′), 138.10 (s, C-1′), 128.53 (d, 2 C, C-3′,5′),

128.10, 127.26 (2 d, 2 × 2 C, C-2′′,3′′,5′′,6′′), 127.19 (d, C-4′′),

127.14 (d, C-4′), 126.82 (d, 2 C, C-2′,6′), 118.62 (s, C-4a), 115.07

(d, C-8), 71.65 (t, OCH₂Ph), 69.13 (t, OCH₂), 49.95 (s, C(CH₃)₃),

46.47 (t, NCH₂), 39.68 (d, C-3), 28.53 (q, 3 C, C(CH₃)₃), 28.22

(t, C-4), 26.39, 24.65 (2 t, 2CH₂), 22.71 (q, CH₃). Anal.

(C₃₂H₃₉N₅O₃) C, H, N.

C. By Reaction with FeCl₃. A solution of 86 (6.1 mg, 11.3

µmol) in CH₂Cl₂(1 mL) was treated with a large excess (ca.

10-fold) of anhydrous FeCl₃. Then the mixture was stirred at

20 °C for 1 h. A solution of aqueous NaHCO₃/Na₂CO₃(50 mL)

was then added, and the mixture was extracted with CH₂Cl₂

(4 × 50 mL). The combined extracts were evaporated to

dryness, and the residue was then chromatographed on silica

gel. Elution with 0-1.5% MeOH/CH₂Cl₂gave foreruns. Then

further elution with 2% MeOH/CH₂Cl₂gave 88 (1.6 mg, 31%).

Further elution with 3-5% MeOH/CH₂Cl₂gave 91 (3 mg,

67%). Repeated reaction with a larger excess of FeCl₃gave 91

as the sole product (55%).

D. By Reaction with DDQ. A solution of 86 (617 mg, 1.14

mmol) and DDQ (1.34 g, 5.89 mmol) in CH₂Cl₂(120 mL) was

stirred in a sealed flask (foil-covered) at 20 °C for 2 days. The

resulting solution was treated with a mixture of aqueous Na₂-

CO₃/sodium sulfite (750 mL) and extracted with CH₂Cl₂(5 ×

300 mL), sequentially washing each extract with (the same)

additional solutions of aqueous Na₂CO₃/Na₂SO₃(750 mL),

aqueous Na₂CO₃(750 mL), and water (2 × 750 mL). The

aqueous portions were further extracted after 18 h (3 × 300

mL). Then the combined extracts were evaporated to dryness,

and the residue was then chromatographed on silica gel.

Elution with 0-1.2% MeOH/CH₂Cl₂gave foreruns. Then

further elution with 1.2-1.4% MeOH/CH₂Cl₂gave recovered

86 (32 mg, 5%). Elution with 1.6-1.8% MeOH/CH₂Cl₂gave

minor impurities. Then elution with 2-5% MeOH/CH₂Cl₂gave

88 (435 mg, 85%): mp (CH₂Cl₂/hexane) 157-159 °C; ¹H NMR

[(CD₃)₂SO] δ 9.88 (br s, 1 H, NH), 9.14 (s, 1 H, H-5), 8.35 (s, 1

H, H-4), 7.67 (s, 1 H, H-8), 7.63 (t, J ) 7.1 Hz, 2 H, H-3′,5′),

Further elution of the column with 1.75% MeOH/CH₂Cl₂

gave a mixture, and then elution with 2-2.3% MeOH/CH₂Cl₂

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4647

with 1-2% MeOH/EtOAc containing 0.5% Et₃N) gave (after

7.58 (m, 3 H, H-2′,4′,6′), 7.21 (br s, 1 H, NH), 4.35 (br t, J )

5.1 Hz, 1 H, CH₂OH), 3.88 (t, J ) 7.2 Hz, 2 H, NCH₂), 3.36

(m, 2 H, CH₂OH), 1.98 (s, 3 H, COCH₃), 1.50 (m, 2 H, CH₂),

1.42 (s, 9 H, C(CH₃)₃), 1.40 (m, 2 H, CH₂); ¹³C NMR δ 169.31

(s, CdO), 154.23, 153.18, 151.57 (3 s, CONH, C-2,7), 151.34

(d, C-5), 148.82 (s, C-8a), 137.34 (d, C-4), 134.75 (s, C-1′), 129.54

(d, 2 C, C-3′,5′), 129.17 (d, C-4′), 129.02 (d, 2 C, C-2′,6′), 127.25

(s, C-3), 118.76 (s, C-4a), 115.55 (d, C-8), 60.32 (t, OCH₂), 50.21

(s, C(CH₃)₃), 46.99 (t, NCH₂), 29.70 (t, CH₂), 28.65 (q, 3 C,

C(CH₃)₃), 24.52 (t, CH₂), 22.97 (q, CH₃). Anal. (C₂₅H₃₁N₅O₃‚

H₂O) C, H, N.

1

base washing) 95 (512 mg, 83%): oil; H NMR [(CD₃)₂SO] δ

9.89 (br s, 1 H, NH), 9.15 (s, 1 H, H-5), 8.35 (s, 1 H, H-4), 7.66

(s, 1 H, H-8), 7.63 (t, J ) 7.1 Hz, 2 H, H-3′,5′), 7.58 (m, 3 H,

H-2′,4′,6′), 7.22 (br s, 1 H, NH), 3.89 (t, J ) 7.1 Hz, 2 H, NCH₂),

2.36 (q, J ) 7.1 Hz, 4 H, N(CH₂)₂), 2.28 (t, J ) 7.0 Hz, 2 H,

NCH₂), 1.98 (s, 3 H, COCH₃), 1.47 (pentet, J ) 7.2 Hz, 2 H,

CH₂), 1.42 (s, 9 H, C(CH₃)₃), 1.36 (pentet, J ) 7.6 Hz, 2 H,

CH₂), 0.87 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 169.26 (s,

CdO), 154.24, 153.14, 151.54 (3 s, CONH, C-2,7), 151.32 (d,

C-5), 148.78 (s, C-8a), 137.32 (d, C-4), 134.72 (s, C-1′), 129.52

(d, 2 C, C-3′,5′), 129.14 (d, C-4′), 128.99 (d, 2 C, C-2′,6′), 127.20

(s, C-3), 118.73 (s, C-4a), 115.52 (d, C-8), 51.74 (t, NCH₂), 50.16

(s, C(CH₃)₃), 46.87 (t, NCH₂), 46.13 (t, 2 C, N(CH₂)₂), 28.62 (q,

3 C, C(CH₃)₃), 25.72, 23.88 (2 t, 2CH₂), 22.96 (q, CH₃), 11.66

(q, 2 C, 2CH₃); HRFABMS calcd for C₂₉H₄₁N₆O₂m/z (MH⁺)

505.3291, found 505.3277.

N-(tert-Butyl)-N′-[7-[[3-(4-methyl-1-piperazinyl)propyl]-

amino]-3-phenyl-1,6-naphthyridin-2-yl]urea (28). A stirred

solution of 94 (87 mg, 0.168 mmol) in MeOH (27 mL) at 0 °C

was treated with NaOH (0.95 g, 23.8 mmol) and water (3 mL,

added dropwise). Then the mixture was stirred at 0 °C for 2 h

and then at 20 °C for 3.5 days. A solution of excess NaHCO₃

(2.15 g, 25.6 mmol) in ice/water (150 mL) was then added, and

the mixture was extracted with CH₂Cl₂(6 × 70 mL). The

combined extracts were evaporated to dryness, and the residue

was then chromatographed on silica gel. Elution with 0-0.5%

MeOH/CH₂Cl₂containing 1% Et₃N gave foreruns. Then further

elution with 0.75-2% MeOH/CH₂Cl₂containing 1% Et₃N gave

(after base washing and crystallization) 28 (54 mg, 68%): mp

(CH₂Cl₂/hexane) 137-138 °C; ¹H NMR [(CD₃)₂SO] δ 10.24 (br

s, 1 H, NH), 8.70 (s, 1 H, H-5), 7.98 (s, 1 H, H-4), 7.58 (t, J )

7.2 Hz, 2 H, H-3′,5′), 7.51 (m, 3 H, H-2′,4′,6′), 6.96 (br t, J )

5.4 Hz, 1 H, NHCH₂), 6.92 (br s, 1 H, NH), 6.39 (s, 1 H, H-8),

3.31 (m, 2 H, NHCH₂), 2.6-2.1 (br s, 8 H, N(CH₂)₄N), 2.38 (t,

J ) 6.8 Hz, 2 H, NCH₂), 2.17 (s, 3 H, NCH₃), 1.72 (pentet, J )

6.9 Hz, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 159.56 (s,

C-7), 152.51, 152.04 (2 s, CONH, C-2), 151.42 (d, C-5), 149.38

(s, C-8a), 137.78 (d, C-4), 135.51 (s, C-1′), 129.45, 129.11 (2 d,

2 × 2 C, C-2′,3′,5′,6′), 128.54 (d, C-4′), 121.19 (s, C-3), 113.31

(s, C-4a), 94.55 (br d, C-8), 55.69 (t, NCH₂), 54.77, 52.70 (2 t,

2 × 2 C, 2N(CH₂)₂), 49.97 (s, C(CH₃)₃), 45.70 (q, NCH₃), 39.82

(t, NCH₂), 28.67 (q, 3 C, C(CH₃)₃), 25.96 (t, CH₂). Anal.

(C₂₇H₃₇N₇O‚0.5H₂O) C, H, N.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-phenyl-1,6-

naphthyridin-7-yl]-N-(3-hydroxypropyl)acetamide (87).

Similar reaction of 85 (869 mg, 1.66 mmol) with DDQ (1.91 g,

8.41 mmol) in CH₂Cl₂(175 mL) at 20 °C for 4 days, then

workup (as above) and chromatography of the resulting

product on silica gel (eluting with 1.2-1.4% MeOH/CH₂Cl₂)

gave firstly recovered 85 (49 mg, 6%). Elution with 1.5-2%

MeOH/CH₂Cl₂gave 87 (429 mg, 60%): mp (Et₂O/hexane) 124-

1

127 °C; H NMR [(CD₃)₂SO] δ 9.88 (br s, 1 H, NH), 9.14 (s, 1

H, H-5), 8.35 (s, 1 H, H-4), 7.70 (s, 1 H, H-8), 7.63 (t, J ) 7.1

Hz, 2 H, H-3′,5′), 7.58 (m, 3 H, H-2′,4′,6′), 7.22 (br s, 1 H, NH),

4.43 (br t, J ) 5.2 Hz, 1 H, CH₂OH), 3.92 (t, J ) 7.3 Hz, 2 H,

NCH₂), 3.41 (q, J ) 5.9 Hz, 2 H, OCH₂), 1.99 (s, 3 H, COCH₃),

1.65 (pentet, J ) 6.8 Hz, 2 H, CH₂), 1.42 (s, 9 H, C(CH₃)₃); ¹³

C

NMR δ 169.78 (s, CdO), 154.37, 153.29, 151.76 (3 s, CONH,

C-2,7), 151.46 (d, C-5), 148.95 (s, C-8a), 137.45 (d, C-4), 134.80

(s, C-1′), 129.69 (d, 2 C, C-3′,5′), 129.33 (d, C-4′), 129.13 (d, 2

C, C-2′,6′), 127.39 (s, C-3), 118.89 (s, C-4a), 115.71 (d, C-8),

58.39 (t, OCH₂), 50.36 (s, C(CH₃)₃), 44.99 (t, NCH₂), 31.19 (t,

CH₂), 28.77 (q, 3 C, C(CH₃)₃), 23.08 (q, CH₃). Anal. (C₂₄H₂₉N₅O₃)

C, H, N.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-phenyl-1,6-

naphthyridin-7-yl]-N-[3-(4-methyl-1-piperazinyl)propyl]-

acetamide (94). A stirred solution of 87 (355 mg, 0.816 mmol)

in dry THF (50 mL) under N₂at 0 °C was treated with dry

N-methylmorpholine (1.50 mL, 14.7 mmol), followed by mesyl

chloride (0.32 mL, 4.13 mmol, added dropwise by syringe).

Then the mixture was stirred at 0-20 °C for 12 h. 1-Meth-

ylpiperazine (9.05 mL, 81.7 mmol) was then added, and the

mixture was stirred at 20 °C for 1 day and then at 30 °C for

1 day. The resulting solution was cooled in ice, then treated

with ice/aqueous Na₂CO₃(150 mL) and extracted with CH₂-

Cl₂(6 × 80 mL). The combined extracts were evaporated to

dryness, and the residue was then chromatographed on silica

gel. Elution with 0-3% MeOH/EtOAc containing 1% Et₃N gave

foreruns. Then further elution with 3-5% MeOH/EtOAc

containing 1% Et₃N gave (after base washing) an oil (410 mg),

which was further chromatographed on silica gel. Elution with

0-7% MeOH/CH₂Cl₂gave foreruns. Then further elution with

7% MeOH/CH₂Cl₂containing 1% Et₃N gave (after base wash-

ing) 94 (280 mg, 66%): oil; ¹H NMR [(CD₃)₂SO] δ 9.90 (br s, 1

H, NH), 9.13 (s, 1 H, H-5), 8.35 (s, 1 H, H-4), 7.69 (s, 1 H,

H-8), 7.63 (t, J ) 7.0 Hz, 2 H, H-3′,5′), 7.57 (m, 3 H, H-2′,4′,6′),

7.22 (br s, 1 H, NH), 3.89 (t, J ) 7.2 Hz, 2 H, NCH₂), 2.5-2.0

(br s, 8 H, N(CH₂)₄N), 2.26 (t, J ) 7.1 Hz, 2 H, NCH₂), 2.09 (s,

3 H, NCH₃), 2.00 (s, 3 H, COCH₃), 1.64 (pentet, J ) 7.1 Hz, 2

H, CH₂), 1.42 (s, 9 H, C(CH₃)₃); ¹³C NMR δ 169.39 (s, CdO),

154.28, 153.13, 151.56 (3 s, CONH, C-2,7), 151.21 (d, C-5),

148.76 (s, C-8a), 137.32 (d, C-4), 134.75 (s, C-1′), 129.53 (d, 2

C, C-3′,5′), 129.15 (d, C-4′), 129.01 (d, 2 C, C-2′,6′), 127.17 (s,

C-3), 118.69 (s, C-4a), 115.46 (d, C-8), 54.80 (t, NCH₂), 54.63,

52.44 (2 t, 2 × 2 C, 2N(CH₂)₂), 50.17 (s, C(CH₃)₃), 45.65 (q,

NCH₃), 45.49 (t, NCH₂), 28.64 (q, 3 C, C(CH₃)₃), 25.10 (t, CH₂),

23.01 (q, CH₃); HRFABMS calcd for C₂₉H₄₀N₇O₂m/z (MH⁺)

518.3244, found 518.3236.

Further base hydrolysis of the mother liquors followed by

chromatography of the resulting product on neutral alumina

(eluting with 1% EtOH/CHCl₃) gave additional 28 (11 mg,

14%).

N-(tert-Butyl)-N′-[7-[[4-(diethylamino)butyl]amino]-3-

phenyl-1,6-naphthyridin-2-yl]urea (31). Similar hydrolysis

of 95 (148 mg, 0.294 mmol) in MeOH (45 mL) with NaOH (1.85

g, 46.3 mmol) and water (5 mL) at 0 °C for 2 h and then at 20

°C for 4 days and chromatography of the resulting product on

silica gel (eluting with 0.5% MeOH/CH₂Cl₂containing 1%

Et₃N) gave (after base washing and crystallization) 31 (101

mg, 74%): mp (CH₂Cl₂/hexane) 124-125 °C; ¹H NMR [(CD₃)₂-

SO] δ 10.25 (br s, 1 H, NH), 8.70 (s, 1 H, H-5), 7.97 (s, 1 H,

H-4), 7.58 (t, J ) 7.2 Hz, 2 H, H-3′,5′), 7.51 (m, 3 H, H-2′,4′,6′),

6.95 (br t, J ) 5.6 Hz, 1 H, NHCH₂), 6.92 (br s, 1 H, NH), 6.38

(s, 1 H, H-8), 3.29 (m, 2 H, NHCH₂), 2.44 (q, J ) 7.1 Hz, 4 H,

N(CH₂)₂), 2.38 (t, J ) 7.1 Hz, 2 H, NCH₂), 1.58 (pentet, J )

7.0 Hz, 2 H, CH₂), 1.48 (pentet, J ) 7.2 Hz, 2 H, CH₂), 1.40 (s,

9 H, C(CH₃)₃), 0.94 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ

159.61 (s, C-7), 152.53, 152.10 (2 s, CONH, C-2), 151.45 (d,

C-5), 149.42 (s, C-8a), 137.82 (d, C-4), 135.54 (s, C-1′), 129.49,

129.14 (2 d, 2 × 2 C, C-2′,3′,5′,6′), 128.57 (d, C-4′), 121.15 (s,

C-3), 113.30 (s, C-4a), 94.50 (br d, C-8), 52.03 (t, NCH₂), 50.00

(s, C(CH₃)₃), 46.21 (t, 2 C, N(CH₂)₂), 41.28 (t, NCH₂), 28.68 (q,

3 C, C(CH₃)₃), 26.84, 24.29 (2 t, 2CH₂), 11.69 (q, 2 C, 2CH₃).

Anal. (C₂₇H₃₈N₆O) C, H, N.

N-[2-[[(tert-Butylamino)carbonyl]amino]-3-phenyl-1,6-

naphthyridin-7-yl]-N-[4-(diethylamino)butyl]aceta-

mide (95). Similar reaction of a stirred solution of 88 (547

mg, 1.22 mmol) and dry N-methylmorpholine (2.05 mL, 18.7

mmol) in dry THF (70 mL) under N₂with mesyl chloride (0.48

mL, 6.20 mmol) at 20 °C for 16 h, followed by reaction with

diethylamine (25 mL, 0.242 mol) at 50 °C for 4 days and

chromatography of the resulting product on silica gel (eluting

N⁷-[3-(4-Methyl-1-piperazinyl)propyl]-3-phenyl-1,6-

naphthyridine-2,7-diamine (27). A stirred solution of 94

(220 mg, 0.426 mmol) in MeOH (54 mL) was treated with

NaOH (2.37 g, 59.3 mmol) and water (6 mL), and the mixture

4648 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

was then sealed under N₂and stirred at 52 °C for 18 h. The

resulting mixture was concentrated under reduced pressure

(to ca. 5 mL), then treated with a solution of excess NaHCO₃

(6.0 g, 71.4 mmol) in water (150 mL) and extracted with CH₂-

Cl₂(6 × 70 mL). The combined extracts were evaporated to

dryness, and the residue (mostly 28) was then dissolved in

dioxane (27 mL), treated with NaOH (2.39 g, 59.8 mmol) and

water (3 mL), and then sealed under N₂and stirred at 96 °C

for 4 days. The resulting mixture was concentrated under

reduced pressure (to ca. 3 mL), then treated with excess

NaHCO₃(150 mL) and extracted with CH₂Cl₂(7 × 70 mL)

and EtOAc (2 × 50 mL). The combined extracts were evapo-

rated to dryness, and the residue was then chromatographed

on silica gel. Elution with 0-4% MeOH/CH₂Cl₂containing 1%

Et₃N gave foreruns. Then further elution with 4-5% MeOH/

CH₂Cl₂containing 1% Et₃N gave (after base washing and

crystallization) 27⁴²(120 mg, 75%). Further purification of the

mother liquors by chromatography on silica gel (eluting with

2.5-3% MeOH/CH₂Cl₂containing 1% Et₃N) gave (after base

washing) additional 27 (12 mg, 8%).

N⁷-[4-(Diethylamino)butyl]-3-phenyl-1,6-naphthyridine-

2,7-diamine (30). Similar hydrolysis of 95 (382 mg, 0.758

mmol) in dioxane (63 mL) with NaOH (5.60 g, 140 mmol) and

water (7 mL) under N₂at 97 °C for 7 days and chromatography

of the resulting product on silica gel (eluting with 5-7%

MeOH/EtOAc containing 1% Et₃N) gave (after base washing

and crystallization) 30 (180 mg, 65%): mp (CH₂Cl₂/hexane)

119-120 °C; ¹H NMR [(CD₃)₂SO] δ 8.46 (s, 1 H, H-5), 7.65 (s,

1 H, H-4), 7.48 (m, 4 H, H-2′,3′,5′,6′), 7.40 (m, 1 H, H-4′), 6.45

(br t, J ) 5.6 Hz, 1 H, NHCH₂), 6.21 (br s, 2 H, NH₂), 6.20 (s,

1 H, H-8), 3.21 (br td, J ) 6.6, 6.1 Hz, 2 H, NHCH₂), 2.44 (q,

J ) 7.1 Hz, 4 H, N(CH₂)₂), 2.37 (t, J ) 7.1 Hz, 2 H, NCH₂),

1.56 (pentet, J ) 7.0 Hz, 2 H, CH₂), 1.47 (pentet, J ) 7.1 Hz,

2 H, CH₂), 0.94 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 159.11,

158.31 (2 s, C-2,7), 152.66 (s, C-8a), 150.38 (d, C-5), 137.65 (s,

C-1′), 136.09 (d, C-4), 128.93, 128.63 (2 d, 2 × 2 C, C-2′,3′,5′,6′),

127.54 (d, C-4′), 120.74 (s, C-3), 113.42 (s, C-4a), 93.78 (d, C-8),

52.08 (t, NCH₂), 46.19 (t, 2 C, N(CH₂)₂), 41.52 (t, NCH₂), 26.87,

24.35 (2 t, 2CH₂), 11.68 (q, 2 C, 2CH₃). Anal. (C₂₂H₂₉N₅) C, H,

N.

CONHCH₂), 25.90 (t, CH₂), 15.15 (q, CH₃). Anal. (C₂₅H₃₁-

Cl₂N₇O) C, H, N.

N-(tert-Butyl)-N′-[3-(2,6-dichlorophenyl)-7-[[3-(4-meth-

yl-1-piperazinyl)propyl]amino]-1,6-naphthyridin-2-yl]-

urea (34). Similar reaction of 32 (115 mg, 0.258 mmol) in dry

DMSO (5 mL) with 60% NaH (15 mg, 0.375 mmol) under N₂

at 40-50 °C for 15 min and then at 20 °C for 30 min followed

by reaction with a solution of tert-butyl isocyanate (37 µL,

0.324 mmol) in dry DMSO (1 mL, then 2 × 1 mL) at 20 °C for

1 day and chromatography of the resulting product on silica

gel (eluting with 3-6% MeOH/EtOAc containing 1% Et₃N)

gave (after base washing and crystallization) 34 (69 mg,

49%): mp (CH₂Cl₂/hexane) 158-159.5 °C; ¹H NMR [(CD₃)₂-

SO] δ 10.33 (br s, 1 H, NH), 8.69 (s, 1 H, H-5), 7.95 (s, 1 H,

H-4), 7.65 (d, J ) 8.0 Hz, 2 H, H-3′,5′), 7.53 (dd, J ) 8.6, 7.6

Hz, 1 H, H-4′), 7.44 (br s, 1 H, NH), 7.03 (br t, J ) 5.5 Hz, 1

H, NHCH₂), 6.38 (s, 1 H, H-8), 3.32 (m, 2 H, NHCH₂), 2.6-2.0

(br s, 8 H, N(CH₂)₄N), 2.37 (t, J ) 7.0 Hz, 2 H, NCH₂), 2.14 (s,

3 H, NCH₃), 1.72 (pentet, J ) 6.9 Hz, 2 H, CH₂), 1.40 (s, 9 H,

C(CH₃)₃); ¹³C NMR δ 159.81 (s, C-7), 152.52, 152.37 (2 s,

CONH, C-2), 151.49 (d, C-5), 149.73 (s, C-8a), 139.49 (d, C-4),

135.48 (s, 2 C, C-2′,6′), 132.58 (s, C-1′), 131.49 (d, C-4′), 128.77

(d, 2 C, C-3′,5′), 116.27 (s, C-3), 112.81 (s, C-4a), 94.39 (br d,

C-8), 55.61 (t, NCH₂), 54.71, 52.64 (2 t, 2 × 2 C, 2N(CH₂)₂),

49.91 (s, C(CH₃)₃), 45.64 (q, NCH₃), 39.75 (t, NHCH₂), 28.64

(q, 3 C, C(CH₃)₃), 25.90 (t, CH₂). Anal. (C₂₇H₃₅Cl₂N₇O) C, H,

N.

3-(2,6-Dichlorophenyl)-N⁷-[4-(diethylamino)butyl]-1,6-

naphthyridine-2,7-diamine (35). A solution of 96 (251 mg,

0.815 mmol) and N¹,N¹-diethyl-1,4-butanediamine (1.19 g, 8.26

mmol) in 2-ethoxyethanol (10 mL) under N₂was stirred at

reflux for 5 days. The solvent was removed under reduced

pressure, then the residue was treated with aqueous Na₂CO₃

(50 mL) and extracted with EtOAc (5 × 50 mL). The extracts

were evaporated to dryness, and the residue was then chro-

matographed on silica gel. Elution with 0.25% MeOH/CH₂Cl₂

gave firstly recovered 96 (36 mg, 14%). Further elution with

15% MeOH/CH₂Cl₂containing 0-0.25% Et₃N gave (after base

washing and crystallization) 35 (125 mg, 36%): mp (CH₂Cl₂/

hexane) 171-172 °C; ¹H NMR [(CD₃)₂SO] δ 8.43 (s, 1 H, H-5),

7.59 (d, J ) 8.2 Hz, 2 H, H-3′,5′), 7.57 (s, 1 H, H-4), 7.46 (dd,

J ) 8.7, 7.4 Hz, 1 H, H-4′), 6.49 (br t, J ) 5.7 Hz, 1 H, NHCH₂),

6.22 (br s, 2 H, NH₂), 6.19 (s, 1 H, H-8), 3.22 (td, J ) 6.5, 6.0

Hz, 2 H, NHCH₂), 2.44 (q, J ) 7.1 Hz, 4 H, N(CH₂)₂), 2.38 (t,

J ) 7.1 Hz, 2 H, NCH₂), 1.57 (pentet, J ) 7.0 Hz, 2 H, CH₂),

1.47 (pentet, J ) 7.1 Hz, 2 H, CH₂), 0.94 (t, J ) 7.1 Hz, 6 H,

2CH₃); ¹³C NMR δ 159.28, 157.68 (2 s, C-2,7), 153.28 (s, C-8a),

150.35 (d, C-5), 136.91 (d, C-4), 135.28 (s, 2 C, C-2′,6′), 134.56

(s, C-1′), 130.60 (d, C-4′), 128.48 (d, 2 C, C-3′,5′), 116.06, 112.58

(2 s, C-3,4a), 93.67 (d, C-8), 52.03 (t, NCH₂), 46.16 (t, 2 C,

N(CH₂)₂), 41.44 (t, NHCH₂), 26.78, 24.31 (2 t, 2CH₂), 11.67 (q,

2 C, 2CH₃). Anal. (C₂₂H₂₇Cl₂N₅) H, N. C: calcd, 61.1; found,

61.7.

N-[3-(2,6-Dichlorophenyl)-7-[[4-(diethylamino)butyl]-

amino]-1,6-naphthyridin-2-yl]-N′-ethylurea (36). Similar

reaction of 35 (101 mg, 0.234 mmol) in dry DMSO (5 mL) with

60% NaH (13 mg, 0.325 mmol) under N₂at 40-50 °C for 15

min and then at 20 °C for 30 min followed by reaction with a

solution of ethyl isocyanate (23 µL, 0.291 mmol) in dry DMSO

(1 mL, then 1 mL) at 20 °C for 16 h and chromatography of

the resulting product on silica gel (eluting with 1-1.5% MeOH/

EtOAc containing 1% Et₃N) gave (after base washing and

crystallization) 36 (74 mg, 63%): mp (CH₂Cl₂/hexane) 102-

109 °C; ¹H NMR [(CD₃)₂SO] δ 10.04 (br t, J ) 5.4 Hz, 1 H,

CONHCH₂), 8.68 (s, 1 H, H-5), 7.94 (s, 1 H, H-4), 7.76 (br s, 1

H, NH), 7.64 (d, J ) 8.3 Hz, 2 H, H-3′,5′), 7.52 (dd, J ) 8.8,

7.4 Hz, 1 H, H-4′), 6.96 (br t, J ) 5.6 Hz, 1 H, NHCH₂), 6.53

(s, 1 H, H-8), 3.30 (m, 4 H, 2NHCH₂), 2.45 (q, J ) 7.2 Hz, 4 H,

N(CH₂)₂), 2.39 (t, J ) 7.2 Hz, 2 H, NCH₂), 1.60 (pentet, J )

6.9 Hz, 2 H, CH₂), 1.49 (pentet, J ) 7.3 Hz, 2 H, CH₂), 1.19 (t,

J ) 7.2 Hz, 3 H, CH₃), 0.94 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C

NMR δ 159.81 (s, C-7), 153.78, 152.33 (2 s, CONH, C-2), 151.45

(d, C-5), 150.10 (s, C-8a), 139.53 (d, C-4), 135.51 (s, 2 C, C-2′,6′),

132.74 (s, C-1′), 131.41 (d, C-4′), 128.74 (d, 2 C, C-3′,5′), 116.21

Further purification of the mother liquors by chromatogra-

phy on alumina (eluting with 0.75-1% MeOH/CH₂Cl₂) gave

additional 30 (41 mg, 15%).

N-[3-(2,6-Dichlorophenyl)-7-[[3-(4-methyl-1-piperazinyl)-

propyl]amino]-1,6-naphthyridin-2-yl]-N′-ethylurea (33).

A solution of 3-(2,6-dichlorophenyl)-N⁷-[3-(4-methyl-1-piper-

azinyl)propyl]-1,6-naphthyridine-2,7-diamine⁴²(32) (112 mg,

0.252 mmol) in dry DMSO (5 mL) was treated with 60% NaH

(13 mg, 0.325 mmol). Then the mixture was sealed under N₂

and stirred at 40-50 °C for 10 min and then at 20 °C for 30

min. A solution of ethyl isocyanate (24 µL, 0.304 mmol) in dry

DMSO (1 mL, then 1 mL to rinse) was added (dropwise via

syringe). Then the mixture was stirred at 20 °C for 1 day. The

resulting mixture was cooled in ice, then treated with ice/

aqueous NaHCO₃(50 mL), adjusted to pH 10 with aqueous

Na₂CO₃, and extracted with EtOAc (5 × 50 mL). The extracts

were evaporated to dryness, and the residue was then chro-

matographed on silica gel. Elution with 0-3% MeOH/EtOAc

containing 1% Et₃N gave foreruns. Then further elution with

3-6% MeOH/EtOAc containing 1% Et₃N gave (after base

washing and crystallization) 33 (94 mg, 72%): mp (CH₂Cl₂/

hexane) 102-106 °C dec; ¹H NMR [(CD₃)₂SO] δ 10.04 (br t, J

) 5.4 Hz, 1 H, CONHCH₂), 8.68 (s, 1 H, H-5), 7.94 (s, 1 H,

H-4), 7.77 (br s, 1 H, NH), 7.64 (d, J ) 8.1 Hz, 2 H, H-3′,5′),

7.52 (dd, J ) 8.7, 7.4 Hz, 1 H, H-4′), 6.95 (br t, J ) 5.6 Hz, 1

H, NHCH₂), 6.53 (s, 1 H, H-8), 3.31 (m, 4 H, 2NHCH₂), 2.6-

2.1 (br s, 8 H, N(CH₂)₄N), 2.38 (t, J ) 7.0 Hz, 2 H, NCH₂),

2.15 (s, 3 H, NCH₃), 1.74 (pentet, J ) 6.9 Hz, 2 H, CH₂), 1.19

(t, J ) 7.2 Hz, 3 H, CH₃); ¹³C NMR δ 159.87 (s, C-7), 153.90,

152.48 (2 s, CONH, C-2), 151.51 (d, C-5), 150.17 (s, C-8a),

139.57 (d, C-4), 135.55 (s, 2 C, C-2′,6′), 132.76 (s, C-1′), 131.47

(d, C-4′), 128.80 (d, 2 C, C-3′,5′), 116.36 (s, C-3), 113.02 (s,

C-4a), 94.48 (br d, C-8), 55.64 (t, NCH₂), 54.73, 52.71 (2 t, 2 ×

2 C, 2N(CH₂)₂), 45.68 (q, NCH₃), 39.95 (t, NHCH₂), 34.15 (t,

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4649

(s, C-3), 112.92 (s, C-4a), 94.32 (br d, C-8), 51.95 (t, NCH₂),

46.16 (t, 2 C, N(CH₂)₂), 41.29 (t, NHCH₂), 34.02 (t, CONHCH₂),

26.63, 24.16 (2 t, 2CH₂), 15.07 (q, CH₃), 11.57 (q, 2 C, 2CH₃).

Anal. (C₂₅H₃₂Cl₂N₆O) C, H, N.

The crude residue was chromatographed on silica gel, eluting

with EtOAc/EtOH/Et₃N (9:2:1) to give N²-[4-(diethylamino)-

butyl]-6-(3,5-dimethoxyphenyl)pyrido[2,3-d]pyrimidine-2,7-di-

amine (109) (2.26 g, 72%): mp 59.5-62.0 °C; ¹H NMR (CDCl₃)

δ 8.61 (s, 1 H, H-4), 7.56 (s, 1 H, H-5), 6.58 (d, J ) 2.2 Hz, 2

H, H-2′,6′), 6.50 (t, J ) 2.2 Hz, 1 H, H-4′), 5.64 (br s, 1 H,

NH), 5.35 (br s, 2 H, NH₂), 3.83 (s, 6 H, 2OCH₃), 3.64-3.55

(m, 2 H, NHCH₂), 2.63-2.46 (m, 6 H, 3NCH₂), 1.75-1.56 (m,

4 H, 2CH₂), 1.04 (t, J ) 7.2 Hz, 6 H, 2CH₃); APCIMS m/z

(relative intensity) 425.6 (M⁺+ 1, 100). Anal. (C₂₃H₃₂N₆O₂‚

0.4H₂O) C, H, N.

A solution of 109 (0.500 g, 1.18 mmol) in dry DMF (4 mL)

was treated with 60% NaH (0.054 g, 1.34 mmol). After the

mixture was stirred at room temperature for 1.5 h, tert-butyl

isocyanate (0.150 mL, 1.34 mmol) was added and the reaction

mixture was allowed to stir at room temperature overnight.

The reaction mixture was concentrated, and the residue was

dissolved in CH₂Cl₂, extracted with saturated aqueous NH₄-

Cl (3x) and saturated aqueous NaCl (1x), dried (MgSO₄) and

evaporated. The residue was chromatographed on silica gel,

eluting with EtOAc/EtOH/Et₃N (9:2:1), to give 12 (0.513 g,

80%): mp 82-86 °C; ¹H NMR (CDCl₃) δ 10.34 (br s, 1 H, NH),

8.70 (br s, 1 H, H-4), 7.66 (s, 1 H, H-5), 7.12 (s, 1 H, NH), 6.51

(t, J ) 2.4 Hz, 1 H, H-4′), 6.47 (d, J ) 2.4 Hz, 2 H, H-2′,6′),

6.00 (br s, 1 H, NH), 3.82 (s, 6 H, 2OCH₃), 3.62-3.52 (m, 2 H,

NHCH₂), 2.57 (q, J ) 7.2 Hz, 4 H, N(CH₂)₂), 2.50 (t, J ) 7.2

Hz, 2 H, NCH₂), 1.88-1.56 (m, 4 H, 2CH₂), 1.49 (s, 9 H,

C(CH₃)₃), 1.06 (t, J ) 7.2 Hz, 6 H, 2CH₃); APCIMS m/z (relative

intensity) 524.5 (M⁺+ 1, 32), 425.6 (M⁺+ 1 - CONC(CH₃)₃,

100). Anal. (C₂₈H₄₁N₇O₃‚0.25H₂O) C, H, N.

N-(tert-Butyl)-N′-[3-(2,6-dichlorophenyl)-7-[[4-(diethy-

lamino)butyl]amino]-1,6-naphthyridin-2-yl]urea (37). Simi-

lar reaction of 35 (101 mg, 0.234 mmol) in dry DMSO (5 mL)

with 60% NaH (14 mg, 0.35 mmol) under N₂at 40-50 °C for

15 min and then at 20 °C for 30 min followed by reaction with

a solution of tert-butyl isocyanate (32 µL, 0.281 mmol) in dry

DMSO (1 mL, then 1 mL) at 20 °C for 17 h and chromatog-

raphy of the resulting product on silica gel (eluting with 3-4%

MeOH/EtOAc containing 0.5% Et₃N) gave (after base washing

and crystallization) 37 (73 mg, 59%): mp (CH₂Cl₂/hexane)

114-116 °C; ¹H NMR [(CD₃)₂SO] δ 10.34 (br s, 1 H, NH), 8.69

(s, 1 H, H-5), 7.94 (s, 1 H, H-4), 7.65 (d, J ) 8.3 Hz, 2 H,

H-3′,5′), 7.53 (dd, J ) 8.6, 7.6 Hz, 1 H, H-4′), 7.43 (br s, 1 H,

NH), 7.03 (br t, J ) 5.4 Hz, 1 H, NHCH₂), 6.38 (s, 1 H, H-8),

3.30 (m, 2 H, NHCH₂), 2.44 (q, J ) 7.1 Hz, 4 H, N(CH₂)₂), 2.38

(t, J ) 7.1 Hz, 2 H, NCH₂), 1.58 (pentet, J ) 7.1 Hz, 2 H, CH₂),

1.47 (pentet, J ) 7.3 Hz, 2 H, CH₂), 1.40 (s, 9 H, C(CH₃)₃),

0.94 (t, J ) 7.1 Hz, 6 H, 2CH₃); ¹³C NMR δ 159.84 (s, C-7),

152.50, 152.37 (2 s, CONH, C-2), 151.48 (d, C-5), 149.74 (s,

C-8a), 139.49 (d, C-4), 135.49 (s, 2 C, C-2′,6′), 132.59 (s, C-1′),

131.49 (d, C-4′), 128.77 (d, 2 C, C-3′,5′), 116.20 (s, C-3), 112.77

(s, C-4a), 94.32 (br d, C-8), 51.97 (t, NCH₂), 49.90 (s, C(CH₃)₃),

46.17 (t, 2 C, N(CH₂)₂), 41.18 (t, NHCH₂), 28.62 (q, 3 C,

C(CH₃)₃), 26.72, 24.23 (2 t, 2CH₂), 11.65 (q, 2 C, 2CH₃). Anal.

(C₂₇H₃₆Cl₂N₆O) C, H, N.

N-(tert-Butyl)-N′-[2-[[4-(diethylamino)butyl]amino]-6-

(3,5-dimethoxyphenyl)pyrido[2,3-d]pyrimidin-7-yl]-

urea (12). A 60% NaH (7.17 g, 179 mmol) sample was washed

with hexane and then suspended in dry THF (250 mL). To

this suspension was added (3,5-dimethoxyphenyl)acetonitrile

(28.9 g, 163 mmol), and the reaction was stirred at room

temperature for 1.5 h. 4-Amino-2-(methylsulfanyl)-5-pyrim-

idinecarbaldehyde^61,62(106) (25 g, 148 mmol) was then added

as fast as foaming of the reaction would allow. After being

stirred overnight at room temperature, the reaction mixture

was concentrated and the residue was partitioned between

CH₂Cl₂and saturated aqueous NH₄Cl. The CH₂Cl₂layer was

washed twice with saturated aqueous NH₄Cl, dried (MgSO₄),

and concentrated to give crude 6-(3,5-dimethoxyphenyl)-2-

(methylsulfanyl)pyrido[2,3-d]pyrimidin-7-amine (107) (50.0 g,

98%): mp 175-178 °C; ¹H NMR [(CD₃)₂SO] δ 8.88 (s, 1 H,

H-4), 7.90 (s, 1 H, H-5), 7.67 (br s, 2 H, NH₂), 6.63 (d, J ) 2.2

Hz, 2 H, H-2′,6′), 6.57 (t, J ) 2.2 Hz, 1 H, H-4′), 3.80 (s, 6 H,

2OCH₃), 2.55 (s, 3 H, CH₃), traces of starting nitrile also

observed in ¹H NMR; APCIMS m/z (relative intensity) 329 (M⁺

+ 1, 100). Anal. (C₁₆H₁₆N₄O₂S‚0.1C₁₀H₁₁NO₂) C, H, N.

A solution of 107 (20.0 g, 60.9 mmol) in CHCl₃(480 mL)

was treated with 2-(phenylsulfonyl)-3-phenyloxaziridine (15.9

g, 60.9 mmol), and the reaction was stirred at room temper-

ature for 24 h. Silica gel was then added, the suspension was

evaporated to dryness, and the residue was chromatographed

on silica gel, eluting with EtOAc/EtOH/Et₃N (9:1:0.5). Product

was crystallized from several fractions and was filtered off and

washed with eluting solvent followed by Et₂O to give 6-(3,5-

dimethoxyphenyl)-2-(methylsulfinyl)pyrido[2,3-d]pyrimidin-7-

amine (108) (9.38 g, 45%): mp 204.5-205.5 °C; ¹H NMR

(CDCl₃) δ 9.20 (s, 1 H, H-4), 7.90 (s, 1 H, H-5), 6.53-6.64 (m,

3 H, H-2′,4′,6′), 6.14 (br s, 1 H, NH), 5.79 (br s, 1 H, NH), 3.86

(s, 6 H, 2OCH₃), 3.05 (s, 3 H, CH₃); APCIMS m/z (relative

intensity) 345.1 (M⁺+ 1, 100). Anal. (C₁₆H₁₆N₄O₃S) C, H, N,

S.

N-[2-[[4-(Diethylamino)butyl]amino]-6-(3,5-dimethox-

yphenyl)pyrido[2,3-d]pyrimidin-7-yl]-N′-ethylurea (104).

Similar reaction of 109 (0.500 g, 1.18 mmol), 60% NaH (0.054

g, 1.34 mmol), and ethyl isocyanate (0.110 mL, 1.34 mmol)

gave 104 (0.378 g, 63%): mp 48-53 °C; ¹H NMR (CDCl₃/D₂O)

δ 8.73 (br s, 1 H, H-4), 7.68 (s, 1 H, H-5), 6.53 (t, J ) 2.2 Hz,

1 H, H-4′), 6.48 (d, J ) 2.2 Hz, 2 H, H-2′,6′), 3.83 (s, 6 H,

2OCH₃), 3.59 (t, J ) 6.8 Hz, 2 H, NHCH₂), 3.46 (q, J ) 7.2

Hz, 2 H, NHCH₂CH₃), 2.58 (q, J ) 7.2 Hz, 4 H, N(CH₂)₂), 2.51

(t, J ) 7.2 Hz, 2 H, NCH₂), 1.82-1.57 (m, 4 H, 2CH₂), 1.30 (t,

J ) 7.2 Hz, 3 H, CH₃), 1.06 (t, J ) 7.2 Hz, 6 H, 2CH₃); APCIMS

m/z (relative intensity) 496.5 (M⁺+ 1, 40), 451.5 (M⁺+ 1 -

NH₂CH₂CH₃, 10), 425.6 (M⁺+ 1 - CONCH₂CH₃, 100). Anal.

(C₂₆H₃₇N₇O₃‚0.6H₂O) C, H, N.

N-[6-(3,5-Dimethoxyphenyl)-2-[[3-(4-methyl-1-piper-

azinyl)propyl]amino]pyrido[2,3-d]pyrimidin-7-yl]-N′-eth-

ylurea (102). Reaction of 108 (0.500 g, 1.45 mmol) and 3-(4-

methyl-1-piperazinyl)propylamine (0.250 g, 1.60 mmol) in dry

dioxane (4.00 mL) as above followed by chromatography on

silica gel, eluting with EtOAc/EtOH/Et₃N (9:2:1 then 9:2:2),

gave 6-(3,5-dimethoxyphenyl)-N²-[3-(4-methyl-1-piperazinyl)-

propyl]pyrido[2,3-d]pyrimidine-2,7-diamine (110) (0.517 g,

1

80%): mp 77-80.5 °C; H NMR (CDCl₃) δ 8.61 (s, 1 H, H-4),

7.56 (s, 1 H, H-5), 6.58 (d, J ) 2.2 Hz, 2 H, H-2′,6′), 6.50 (t, J

) 2.2 Hz, 1 H, H-4′), 6.07 (br s, 1 H, NH), 5.33 (br s, 2 H,

NH₂), 3.83 (s, 6 H, 2OCH₃), 3.71-3.60 (m, 2 H, NHCH₂), 2.79-

2.22 (m, 13 H, 5NCH₂, CH₃), 1.85 (pentet, J ) 6.7 Hz, 2 H,

CH₂); APCIMS m/z (relative intensity) 438.1 (M⁺+ 1, 100).

Anal. (C₂₃H₃₁N₇O₂‚0.25H₂O) C, H, N.

Reaction of 110 (0.200 g, 0.457 mmol), 60% NaH (0.020 g,

0.503 mmol), and ethyl isocyanate (0.040 mL, 0.503 mmol) as

above gave 102 (0.134 g, 56%): mp 68-73 °C; ¹H NMR (CDCl₃/

D₂O) δ 8.72 (s, 1 H, H-4), 7.67 (s, 1 H, H-5), 6.58-6.41 (m, 3

H, H-2′,4′,6′), 3.82 (s, 6 H, 2OCH₃), 3.73-3.59 (m, 2 H,

NHCH₂), 3.53-3.38 (m, 2 H, NHCH₂CH₃), 2.96-2.22 (m, 13

H, 5NCH₂, CH₃), 1.95-1.77 (m, 2 H, CH₂), 1.30 (t, J ) 7.2 Hz,

3 H, CH₃); APCIMS m/z (relative intensity) 509.0 (M⁺+ 1,

23), 463.9 (M⁺+ 1 - NH₂CH₂CH₃, 13), 437.9 (M⁺+ 1 -

CONCH₂CH₃, 100). Anal. (C₂₆H₃₆N₈O₃‚0.6H₂O) C, H, N.

N-(tert-Butyl)-N′-[6-(3,5-dimethoxyphenyl)-2-[[3-(4-meth-

yl-1-piperazinyl)propyl]amino]pyrido[2,3-d]pyrimidin-

7-yl]urea (103). Similar reaction of 110 (0.223 g, 0.509 mmol),

60% NaH (0.022 g, 0.560 mmol), and tert-butyl isocyanate

(0.064 mL, 0.560 mmol) gave 103 (0.173 g, 63%): mp 127-

The remaining fractions from the chromatography were

concentrated and rechromatographed on silica gel as above to

give additional 108 (8.92 g, 43%).

N¹,N¹-Diethyl-1,4-butanediamine (1.15 g, 7.99 mmol) was

added to a suspension of 108 (2.50 g, 7.26 mmol) in dry dioxane

(20.0 mL). The suspension was warmed at 50 °C overnight,

the solvent was evaporated, and the residue was dissolved in

CH₂Cl₂and washed with saturated aqueous NaHCO₃(3×) and

saturated aqueous NaCl (2×), dried (MgSO₄), and evaporated.

4650 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14

Thompson et al.

132 °C; ¹H NMR (CDCl₃) δ 10.31 (br s, 1 H, NH), 8.70 (br s, 1

H, H-4), 7.65 (s, 1 H, H-5), 7.12 (s, 1 H, NH), 6.51 (t, J ) 2.2

Hz, 1 H, H-4′), 6.47 (d, J ) 2.2 Hz, 2 H, H-2′,6′), 6.41 (br s, 1

H, NH), 3.82 (s, 6 H, 2OCH₃), 3.42-3.31 (m, 2 H, NHCH₂),

2.93-2.13 (m, 13 H, 5NCH₂, CH₃), 1.93-1.78 (m, 2 H, CH₂),

1.49 (s, 9 H, C(CH₃)₃); APCIMS m/z (relative intensity) 537.0

(M⁺+ 1, 15), 463.9 (M⁺+ 1 - NH₂C(CH₃)₃, 9), 437.9 (M⁺+ 1

- CONC(CH₃)₃, 100). Anal. (C₂₈H₄₀N₈O₃‚0.25H₂O) C, H, N.

N-(tert-Butyl)-N′-[6-(3,5-dimethoxyphenyl)-2-[(3-hydrox-

ypropyl)amino]pyrido[2,3-d]pyrimidin-7-yl]urea (105). A

mixture of 108 (2.00 g, 5.81 mmol) and 3-amino-1-propanol

(1.30 g, 17.42 mmol) in dioxane (25 mL) was heated at reflux

for 18 h. The solvent was removed under reduced pressure,

and the residue was partitioned between hexane and saturated

aqueous NaHCO₃. The insoluble crude product was collected

by filtration and dried under high vacuum at 50 °C overnight

to give crude 3-[[7-amino-6-(3,5-dimethoxyphenyl)pyrido[2,3-

d]pyrimidin-2-yl]amino]-1-propanol (111) (2.0 g, 92%), which

was used directly: ¹H NMR [(CD₃)₂SO] δ 8.58 (br s, 1 H, H-4),

7.61 (s, 1 H, H-5), 7.24 (br s, 1 H, NH), 6.52 (m, 2 H, H-2′,6′),

6.50 (m, 1 H, H-4′), 4.60 (br s, 1 H, OH), 3.73 (s, 6 H, 2OCH₃),

3.68-3.44 (m, 2 H, CH₂OH), 3.43-3.40 (m, 2 H, NHCH₂),

1.68-1.62 (m, 2 H, CH₂); APCIMS m/z (relative intensity) 356

(M⁺+ 1, 100).

To a solution of crude 111 (1.79 g, 5.04 mmol) in DMF (4

mL) was added imidazole (0.86 g, 12.6 mmol) followed by tert-

butyl(chloro)dimethylsilane (0.91 g, 6.04 mmol). The mixture

was stirred at ambient temperature overnight, and the solvent

was removed under high vacuum. The residue was dissolved

in EtOAc and washed with brine, followed by water, and then

dried over MgSO₄. The suspension was filtered, and the solvent

was evaporated under reduced pressure. The crude product

was purified by radial chromatography, eluting with CH₂Cl₂/

MeOH (97:3), to give N²-[3-[[tert-butyl(dimethyl)silyl]oxy]-

propyl]-6-(3,5-dimethoxyphenyl)pyrido[2,3-d]pyrimidine-2,7-

diamine (112) (1.72 g, 73%): mp 168-170 °C; ¹H NMR (CDCl₃)

δ 8.54 (br s, 1 H, H-4), 7.49 (s, 1 H, H-5), 6.51-6.50 (m, 2 H,

H-2′,6′), 6.43-6.42 (m, 1 H, H-4′), 5.63 (br s, 1 H, NH), 5.30

(br s, 2 H, NH₂), 3.76 (s, 6 H, 2OCH₃), 3.71 (t, J ) 6.0 Hz, 2 H,

OCH₂), 3.66-3.58 (m, 2 H, NHCH₂), 1.85-1.80 (m, 2 H, CH₂),

0.84 (s, 9 H, (CH₃)₃CSi(CH₃)₂), 0.00 (s, 6 H, (CH₃)₃CSi(CH₃)₂);

APCIMS m/z (relative intensity) 470 (M⁺+ 1, 100). Anal.

(C₂₄H₃₅N₅O₃Si) C, H, N.

NHCH₂), 1.79-1.76 (m, 2 H, CH₂), 1.46 (s, 9 H, C(CH₃)₃);

APCIMS m/z (relative intensity) 455 (M⁺+ 1, 100), 356 (M⁺

+

1 - CONC(CH₃)₃, 100). Anal. (C₂₃H₃₀N₆O₄‚0.36EtOAc) C, H, N.

DELFIA Assay. Clear, solid polystyrene 96-well DELFIA

plates (DELFIA is a time-resolved dissociation-enhanced lan-

thanide fluoroimmunoassay) (EG&G Wallac, Gaithersburg

MD) were coated with 100 µL/well of 0.1 mg/mL of poly(Glu-

Tyr) (4:1) (Sigma, St. Louis, MO) in BupH carbonate/bicarbon-

ate buffer (0.2 M sodium carbonate/bicarbonate buffer, pH 9.4,

Pierce, Rockford, IL) overnight at room temperature. Excess

substrate was removed by washing the plate 3× with 100 µL

of 1× DELFIA wash reagent (EG&G Wallac, Gaithersburg

MD) and stored wrapped at -20 °C. Plates are spotted with 1

µL of inhibitor (typically 10-30 µM final) or DMSO carrier

control and restored as above.

Preparation of VEGFR-2 TK. The VEGFR-2 TK construct

was prepared and purified at Agouron, La Jolla, CA. VEGFR-2

[also known in the literature as KDR (human) and Flk-1

(mouse)] is a member of the PDGF receptor family, a group of

membrane-bound receptors that characteristically contain a

kinase insert domain (KID) in the intracellular catalytic

domain. The KID is a structural feature not necessary for

intrinsic kinase activity but, after ligand-stimulated autophos-

phorylation, one that binds signaling proteins. The VEGFR-2

TK protein was designed using homology to the PDGF RTK

and comprises the intracellular domain of the receptor.⁶⁵It

was further truncated by the deletion of 50 amino acids of the

68-residue KID to yield a protein of approximately 36 kDa.

Removal of this internal fragment does not significantly affect

kinase activity of the final construct. Protein is expressed from

a baculovirus vector. Cell pellets were lysed, and the soluble

portion was purified to homogeneity by successive chroma-

tography on (a) Q-30 anion-exchange column (Pharmacia,

Piscataway, NJ), (b) hydroxyapatite column (Bio-Rad, Her-

cules, CA), (c) Q-15 anion-exchange column (Pharmacia), (d)

HP-phenyl sepharose column (Pharmacia), and (e) G-25 col-

umn (Pharmacia).⁷⁰Final material was aliquoted and flash-

frozen in liquid N₂and stored at -70 °C. Just before use, the

protein was thawed on ice and autophosphorylated as de-

scribed in the assay protocol.

Human FGFR1 Kinase Domain. A baculovirus was

prepared that expressed the human FGFR1 cytoplasmic,

kinase domain, amino acids 456-822, with an N-terminal

Flag-tag.⁷¹This virus was used to infect either SF9 or Hi5

insect cells, and the infected cells were harvested 48-60 h after

infection. After being harvested, the cells were washed with

phosphate buffered saline and frozen at -70 °C until purifica-

tion. The cells from a 1 L infected culture were thawed and

resuspended in 20-30 mL of buffer A (25 mM Tris-Cl, pH 7.5,

5 mM EDTA, 0.1% (v/v) NP-40) and a protease inhibitor

cocktail [Boehringer-Mannheim 1836170] at 4 °C. The resus-

pended cells were lysed on ice with 2 × 1 min pulses from a

Branson model 250 sonicator at 70% duty, output 7. Debris

was pelleted from the lysed cells by centrifugation at 4 °C in

a Beckman SS-34 rotor at 11 000 rpm for 10 min. NaCl was

added to the soluble protein to a final concentration of 0.15

M, 3-5 mL of M2 anti-Flag antibody resin (Sigma A1205) was

added, and the suspension was mixed by inversion at 4 °C for

2-4 h. The mixture was centrifuged for 1-3 min at 4 °C at

1000g, and the supernatant was removed. The resin was

washed once with 10 mL of buffer A + 0.15 M NaCl and five

times with 10-20 mL of ice cold buffer B (50 mM Tris-Cl, pH

7.5, 150 mM NaCl). Each time, the resin was resuspended in

the buffer by inversion of the tube and then centrifuged for

1-3 min at 4 °C at 1000g and the supernatant was removed.

After the final wash, the resin was resuspended in ice cold

buffer B and put into a (1 cm × 10 cm) Econo column (BioRad).

The resin was further washed with buffer B until no protein

could be detected in the eluate using the BioRad protein

detection agent (20 µL of detection reagent + ∼100 µL of

eluate). The Flag-tagged FGFR1 fusion protein was eluted

from the column with 4 × 5 mL of ice cold buffer B containing

100 µg/mL of Flag peptide (Sigma F3290). The eluate was

buffer-exchanged into 25 mM Hepes (or Tris-Cl), pH 7.5, 50

To a solution of 112 (1.72 g, 3.66 mmol) in DMF (20 mL)

was added 60% NaH (0.16 g, 4.03 mmol) in portions. The

mixture was stirred at ambient temperature for 30 min, and

then tert-butyl isocyanate (0.40 g, 4.03 mmol) was added. The

reaction mixture was stirred for 18 h at room temperature,

then the solvent was removed under high vacuum and the

residue was diluted with water. The insoluble crude product

was collected by filtration, dried on the filter, and purified by

radial chromatography, eluting with a gradient of 20-50%

EtOAc/hexane, to give N-(tert-butyl)-N′-[2-[[3-[[tert-butyl(dim-

ethyl)silyl]oxy]propyl]amino]-6-(3,5-dimethoxyphenyl)pyrido-

[2,3-d]pyrimidin-7-yl]urea (113) (1.44 g, 69%): mp (broad)

1

120-157 °C; H NMR (CDCl₃) δ 8.60 (br s, 1 H, H-4), 7.57 (s,

1 H, H-5), 7.07 (br s, 1 H, NH), 6.43-6.40 (m, 1 H, H-4′), 6.40-

6.38 (m, 2 H, H-2′,6′), 5.90 (br s, 1 H, NH), 3.73 (s, 6 H, 2OCH₃),

3.72 (t, J ) 5.9 Hz, 2 H, OCH₂), 3.61-3.56 (m, 2 H, NHCH₂),

1.83 (br m, 2 H, CH₂), 1.41 (s, 9 H, CONHC(CH₃)₃), 0.84 (s, 9

H, (CH₃)₃CSi(CH₃)₂), 0.00 (s, 6 H, (CH₃)₃CSi(CH₃)₂). Anal.

(C₂₉H₄₄N₆O₄Si) C, H, N.

To a mixture of 113 (1.40 g, 2.46 mmol) in 50% CH₃CN/

THF (50 mL) was added fluorosilicic acid (20-25% solution

in water, 4 mL), and the reaction mixture was stirred for 2 h

at room temperature. The solvent was removed under reduced

pressure, and the residue was triturated with a half-saturated

aqueous solution of NaHCO₃. The insoluble product was

collected by filtration, washed with water, and dried in air to

give 105 (0.9 g, 80%): mp 157-159 °C; ¹H NMR (CDCl₃) δ

9.92 (br s, 1 H, NH), 8.67 (br s, 1 H, H-4), 7.63 (s, 1 H, H-5),

7.12 (br s, 1 H, NH), 6.48-6.46 (m, 1 H, H-4′), 6.43-6.41 (m,

2 H, H-2′,6′), 5.70 (br s, 1 H, NH), 5.05 (br s, 1 H, OH), 3.78 (s,

6 H, 2OCH₃), 3.73-3.69 (m, 2 H, CH₂OH), 3.60-3.56 (m, 2 H,

1,6-Naphthyridines as Dual FGFR-VEGFR Inhibitors

Journal of Medicinal Chemistry, 2005, Vol. 48, No. 14 4651

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mM NaCl, 10% (v/v) glycerol using a PD-10 column (Amer-

sham-Pharmacia) and concentrated using a Centriprep 30

concentration unit (Amicon). Final protein concentration was

determined using the Pierce BCA protein assay (usually 0.3-

1.0 mg/mL), and the protein was stored at -70 °C until needed.

Kinase Autophosphorylation. Kept to a final 20× con-

centration, kinase was incubated in 4 mM ATP and 25 mM

MgCl₂agitated at 4 °C for 45 min.

Reaction with Inhibitors. Kinase solution (40 nM) was

prepared by diluting stock protein preparation (typically 1-0.3

mg/mL) in a final concentration of 20 mM MgCl₂, 20 mM Tris,

50 mM NaCl, 5 mM DTT, 10% (v/v) glycerol, 2 Complete Mini

EDTA-free protease inhibitor cocktail tablets (Boehringer

Mannheim, Indianapolis IN). ATP was likewise diluted to 66.6

µM. An amount of 50 µL of each was added per well, and the

plate was allowed to incubate, with agitation, for 30 min at

room temperature. Plates were washed four times with 300

µL 1× DELFIA wash reagent. To block nonspecific signaling,

an amount of 150 µL of blocking buffer (0.5% (w/v) BSA in

DELFIA assay buffer, Sigma and EG&G, respectively) was

added per well and allowed to incubate, with agitation for 30

min. Washing was repeated. An amount of 100 µL of europium-

conjugated antiphosphotyrosine antibody was added to each

well at a dilution of 1:14386 (7 ng per well, equivalent to 0.07

µg/mL) and allowed to gently rock for 1 h. Because residual

water interferes with signaling, plates were dried inverted for

30 min on paper toweling. An amount of 100 µL of Enhance-

ment Solution (EG&G Wallac, Gaithersburg MD) was added

and allowed to stand for 5 min. Plates were read in a VICTOR

1420 time-resolved fluorometer (EG&G Wallac, Inc).

IC₅₀Calculation Method. The value for percent of control

(% C) for each inhibitor concentration was determined using

the following relationship: % C ) [(fluorescence of sample)/

(value for fluorescence of uninhibited reaction)] × 100, where

the value for the uninhibited reaction is equal to the average

of eight reactions in column 12, which contains vehicle in place

of inhibitor concentration. Compounds are tested using half-

log dilutions from 10 through 0.0001 µM. IC₅₀values are

calculated by least squares regression using the Hill equation

where the limits are set from 0% C to 100% C and the slope

and inflection point are varied for the best fit of all the points

in the dose response curve to the kinetic model.

Acknowledgment. This work was partially sup-

ported by the Auckland Division of the Cancer Society

of New Zealand.

Supporting Information Available: Tables of elemental

analysis results, solubility data for selected compounds (14,

16, 18-20, 22, 23, 25, 26) as their HCl salts, and full

experimental details (including ¹H and ¹³C NMR data) for the

synthesis of 3-(benzyloxy)-1-propanol, 4-(benzyloxy)-1-butanol,

5-(benzyloxy)-1-pentanol, benzyl 3-iodopropyl ether, benzyl

4-iodobutyl ether, benzyl 5-iodopentyl ether, 3-iodopropyl

benzoate, and compounds 61, 64, 73, and 97-101. This

material is available free of charge via the Internet at http://

pubs.acs.org.

(22) Shawver, L. K.; Lipson, K. E.; Fong, T. A. T.; McMahon, G.;

Plowman, G. D.; Strawn, L. M. Receptor tyrosine kinases as

targets for inhibition of angiogenesis. Drug Discovery Today

1997, 2, 50-63.

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JM0500931

Article Doi

Synthesis and structure-activity relationships of soluble 7-substituted 3-(3,5-dimethoxyphenyl)-1,6-naphthyridin-2-amines and related ureas as dual inhibitors of the fibroblast growth factor receptor-1 and vascular endothelial growth factor receptor-2 tyrosine kinases

DOI: 10.1021/jm0500931

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