Synthesis and structure-activity relationships of 5-heteroatom-substituted pyridopyrimidines as adenosine kinase inhibitors

Article abstract of DOI:10.1016/S0223-5234(03)00019-9

Under stressful conditions, many cells release adenosine to minimize tissue damage. Inhibition of intracellular adenosine kinase (AK) increases the local extracellular concentration of adenosine and its effect on traumatized tissue. The synthesis and SAR of a new series of pyridopyrimidines for the inhibition of AK are described. It was found that a range of analogs with position five substituted by an amine or ether functionality increased aqueous solubility while retaining the in vitro potency of initial leads. A narrower range of analogs was active in vivo in a rat inflammatory hyperalgesia model.

Full text of DOI:10.1016/S0223-5234(03)00019-9

European Journal of Medicinal Chemistry 38 (2003) 245ꢀ252
/
www.elsevier.com/locate/ejmech
Original article
Synthesis and structure-activity relationships of 5-heteroatom-
substituted pyridopyrimidines as adenosine kinase inhibitors
Gregory A. Gfesser *, Erol K. Bayburt, Marlon Cowart, Stanley DiDomenico,
Arthur Gomtsyan, Chih-Hung Lee, Andrew O. Stewart, Michael F. Jarvis,
Elizabeth A. Kowaluk, Shripad S. Bhagwat 1
Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA
Received 18 November 2002; received in revised form 8 January 2003; accepted 9 January 2003
Abstract
Under stressful conditions, many cells release adenosine to minimize tissue damage. Inhibition of intracellular adenosine kinase
(AK) increases the local extracellular concentration of adenosine and its effect on traumatized tissue. The synthesis and SAR of a
new series of pyridopyrimidines for the inhibition of AK are described. It was found that a range of analogs with position five
substituted by an amine or ether functionality increased aqueous solubility while retaining the in vitro potency of initial leads. A
narrower range of analogs was active in vivo in a rat inflammatory hyperalgesia model.
´
# 2003 Editions scientifiques et me´dicales Elsevier SAS. All rights reserved.
Keywords: Adenosine; Pyridopyrimidines; Hyperalgesia
1. Introduction
ylates adenosine to AMP [6]. Therefore, we sought to
discover potent and selective AK inhibitors for the
treatment of pain and inflammation.
A novel set of heteroatom-substituted pyridopyrimi-
dine analogs of previously described potent and selective
Under stressful conditions (e.g., pain, inflammation,
ischemia or mechanical trauma) many cells release
adenosine in order to minimize tissue damage [1].
Adenosine stimulates specific receptors (A1, A2A, A2B
,
AK inhibitors 1a (ABT-702) and 1b (Fig. 1) [7ꢀ10] was
/
and A3) on the outer surface of cell membranes,
resulting in decreased excitatory amino acid release,
neutrophil degranulation, and superoxide production
[2]. As the therapeutic utility of direct acting adenosine
receptor agonists has been limited by unacceptable side
effects, our approach was to enhance the naturally
beneficial effects of adenosine at sites of trauma or
designed with the goal of maintaining in vitro potency,
enhancing the basicity of the pyridopyrimidine ring
system, and increasing solubility and absorption. It
has already been found that medium to large-sized
lipophilic substituents in position five of the pyridopyr-
imidine ring system likely provide an additional inter-
action with a binding pocket in AK [10], and that
replacement with an even slightly polar substituent
provided compounds with reduced in vitro activity [9].
However, C-5 analogs with a heteroatom directly
attached to the pyridopyrimidine were projected to
increase the basicity in the ring system and form more
soluble salts. As the receptor site has been found to
tolerate either aromatic or aliphatic substituents at C-5,
both aromatic and aliphatic groups were attached to the
heteroatom with the aim of balancing solubility with
potency. In the present paper we describe the synthesis,
hyperexcitability by inhibiting its metabolism [3ꢀ5]. The
/
primary enzyme responsible for the inactivation of
adenosine is adenosine kinase (AK), which phosphor-
* Corresponding author. Address: Neuroscience Research, Global
Pharmaceutical Research and Development, Abbott Laboratories, D-
4MN, AP9A, Room 216, 100 Abbott Park Road, Abbott Park, IL
60064, USA.
E-mail address: greg.gfesser@abbott.com (G.A. Gfesser).
1
Present address: Celgene Corporation, Signal Research Division,
5555 Oberlin Drive, San Diego, CA 92121, USA.
´
0223-5234/03/$ - see front matter # 2003 Editions scientifiques et me´dicales Elsevier SAS. All rights reserved.
doi:10.1016/S0223-5234(03)00019-9

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G.A. Gfesser et al. / European Journal of Medicinal Chemistry 38 (2003) 245ꢀ252
/
Fig. 1. Lead compounds 1a and 1b.
solubility, and in vitro activity of these novel, potent AK
inhibitors.
Fig. 3. Preparation of aryl methylsulphides 7 and 5a.
methylenic protons alpha to a carbonyl suggested that a
cyclization had already taken place. When this inter-
mediate was refluxed with ammonium acetate in di-
chloroethane, 5a was obtained. Later, the overall yield
was improved by changing the base in the first step to
sodium tert-butoxide and by adding acetic acid in the
second.
2-Aminopyridine 5a was heated with catalytic ammo-
nium sulphate in triethyl orthoformate to afford the
imino ether, which was immediately converted to the
amidine by addition of 2 M ammoniacal ethanol (Fig.
4). The crude product was subsequently heated in
dichlorobenzene to provide the desired pyridopyrimi-
dine 8 in an overall yield of 23% from 3. The oxidation
of 8 to 9 with Oxone† (2KHSO5/KHSO4/K2SO4)
required a mixture of three solvents to keep all of the
reactive species in solution, but succeeded in 74% yield.
Compounds 8 and 9 were both used to prepare the
targeted series of compounds.
Attempted substitution of the methyl sulphide in 8
with piperidine in either refluxing butanol or diglyme
failed. Once the substrate was changed to the more
electrophilic 9, substitution of the sulphone with most
primary aliphatic amines occurred smoothly in hot
DMSO to give 10 (Fig. 5).
Secondary aliphatic amines reacted similarly, but in
poor yield. Therefore, an alternative synthetic route was
explored, wherein most secondary amines were first
reacted with 6 to give intermediate 11 (Fig. 5). 11 was
then stirred with acetylpyridine 3 in DMSO and treated
with lithium tert-butoxide for 2 h, after which the
reaction was quenched with acetic acid and heated with
2. Chemistry
The original synthesis of the lead compounds had
required the condensation of a substituted 1,1-dicya-
noethylene 2 and acetylpyridine 3 with ammonium
acetate (Fig. 2). However, our first attempts to prepare
5-heteroatom analogs in a similar manner failed to
produce the desired product and afforded unsubstituted
4 instead. One plausible mechanism is consistent with
actual observations: After 2 reacts with 3 to give
intermediate I, ammonia can condense with I to provide
dihydropyridine II, which then readily air oxidizes to
pyridine 5 if R is not a heteroatom. On the other hand, if
R is a readily eliminated group the second pathway is
favoured and results in 4.
In order to compensate for this elimination, we used
as a starting material a compound where two thiomethyl
groups were attached to the dicyanoethylene, with the
aim that after one was eliminated the second would
remain and could be substituted at a later time. But
when 2,2-dicyano-1,1-dithiomethylethylene (6) was used
under identical reaction conditions, no products were
formed.
Tominaga reported in 1987 [11] that 6 reacted with
acetone in the presence of KOH in DMSO to give 7 after
an acid quench (Fig. 3). We hypothesized that a similar
reaction of 6 with 3 and ammonium acetate might
produce 5a instead. What was obtained, in poor yield,
was an intermediate which possessed a mass equivalent
to the sum of the masses of 6 and 3, with no sign of
ammonia incorporation. The absence of evidence for
Fig. 2. Mechanisms for the formation of pyridines 4 and 5.
Fig. 4. The synthesis of sulphone 9.

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247
by methods previously described (Tables 1 and 2) [7].
The whole cell assay was conducted to ascertain whether
the compounds were able to penetrate cell membranes
and inhibit AK intracellularly.
The biological data for series 10 and 12 reveal a
general trend among those compounds found potent in
both assays: They possess the same type of moderately
large hydrophobic substituents found in the lead com-
pounds. For example, an increase in the size of the
substituent ring in 12aꢀd from five to eight enhances
/
potency at the cytosolic AK from 81 to 4 nM, and in the
whole cell assay from 560 to 32 nM; however, com-
pound 12e, which possesses a larger substituent, has a
substantially lesser potency. This preference for moder-
ately-sized groups carries over to monosubstituted
derivatives 10a and 10b, where the larger 10b is more
potent than its smaller analog. An apparent exception in
this trend is 10c, anomalously less potent than 10a, with
a similar trend from 10f to 10g, 10h to 10i, and 12d to
12f. One explanation consistent with these data is that
the extra degrees of freedom in the larger systems lower
affinity for the enzyme.
Fig. 5. The syntheses of 5-alkylamino-pyridopyrimidines.
ammonium acetate to afford 5b. Heating 5b with
ammonium sulphate in triethyl orthoformate afforded
the imino ether, and this could be converted to the
amidine by addition of 2 M ammoniacal ethanol as with
5a. These amidines were then heated with sodium
methoxide in THF/MeOH to obtain the desired 12.
The less reactive anilines reacted with 9 in poor yield
and only after deprotonation with KH (Fig. 6). The
reaction was sometimes found to be accelerated upon
addition of diglyme or moderate heating.
Sodium alkoxides reacted cleanly with sulphide 8 to
give ethers 14 (Fig. 6). Propyl ether 14a was prepared by
adding the sulphide to a solution of sodium metal in
propanol and then refluxing for 2.5 h. Cyclohexyl ether
14b was obtained by dissolving sodium hydride and
cyclohexanol into THF, adding a DMSO solution of 8,
and then refluxing overnight. As expected, phenol
reacted with sulphone 9 in the presence of KH and in
good yield, providing 15.
Arylamines 13 were all found to be either comparable
or inferior to compounds 10 and 12, and at least appear
to favour unsubstituted rings and disubstitution of the
nitrogen (Table 2). 2-trifluoromethylaniline 13b is less
potent than aniline 13a in both assays, with an IC50 of
270 nM vs. 83 nM in broken cells and an IC50 of 650 nM
vs. 340 nM in whole cells. Disubstituted anilines 13d-e
showed approximately two-fold greater affinities for AK
than the parent 13a, and were also considerably more
soluble than 13b. The indoline 13e was even soluble to
the extent of 100 mg mLꢁ1
.
Few ethers were prepared, but it was found that both
aliphatic and aromatic ethers could be potent AK
antagonists with moderate solubility (Table 2). Cyclo-
hexyl 14b is ten-fold more potent at AK than the smaller
propyl 14a, as would be expected from the trend among
the amines. But although the potency of ethers 14b and
15 were significantly greater than their nitrogen analogs,
14c binds much more poorly than does amine 10f (140
3. Results and discussion
Compounds 10aꢀ
/
g, 12aꢀ
/
i, 13aꢀ
/
e, 14aꢀc, and 15 were
/
converted to a hydrochloride salt and tested for inhibi-
tion of AK in both enzyme and intact (IMR) cell assays
nM vs 9 nM in broken cells and ꢀ/2000 nM vs 220 nM
in the whole cell assay).
A number of these new AK inhibitors were assayed in
a carrageenan-induced thermal hyperalgesia model of
inflammatory pain (Table 3): In this model a dilute
saline solution of l-carrageenan was injected into the
plantar surface of a rat’s hindpaw. After 2 h radiant heat
from a projection bulb was focused on the same paw,
and the time elapsed until its quick withdrawal was
measured [8]. Withdrawal latencies were increased by
four compounds when administered intraperitoneally at
30 mmol kgꢁ1 (10d, 10f, 12c, 13e). Neither of the ethers
tested demonstrated efficacy, but at least one compound
from each amine series did. While this may in part be
due to the increased solubility of the amines, solubility
Fig. 6. The synthesis of anilines 13 and ethers 14 and 15.

248
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/
Table 1
In vitro activity of substituted 5-alkylamnio-pyridopyrimidines (10, 12)
and in vitro potency in themselves could not guarantee
in vivo activity (e.g., 10e, 12h).
4.1. 6-Amino-4-methylsulfanyl-6?-morpholin-4-yl-
[2,3?]bipyridinyl-5-carbonitrile (5a)
In summary, we were successful in the preparation of
compounds which possessed significant in vitro and in
vivo activity (e.g., 10f carrageenan-induced inflamma-
2-(Bis-methylsulfanyl-methylene)-malononitrile
(6)
(851 mg, 5.00 mmol), 1-(6-morpholin-4-yl-pyridin-3-
yl)-ethanone (3) (1031 mg, 5.00 mmol), and sodium
tert-butoxide (961 mg, 10.0 mmol) were stirred together
in DMSO (5 mL) for 1 h. The mixture was diluted with
water (40 mL) and acidified by dropwise addition of
acetic acid. The solids were collected by filtration,
tory hyperalgesia ED50ꢂ
/
10 mmol kgꢁ1 i.p.), and dis-
played high solubility (e.g., 10fꢀ
/
200 mg mLꢁ1).
dissolved into methanolꢀdichloromethane, concen-
/
4. Experimental protocols
trated to an oil and triturated from dichloromethane
with ether. The resulting tan precipitate was collected by
1H-NMR spectra were measured on 300 MHz spec-
trometers, using tetramethylsilane as internal reference;
chemical shifts are expressed in ppm. Elemental com-
bustion analyses, carried out on each of the final
compounds as either the free base or solvated salt,
were obtained for C, H, and N from Robertson Microlit
filtration, washed with additional dichloromethaneꢀ
/
ether, and dried under vacuum (738 mg).
This intermediate (731 mg) and ammonium acetate
(1050 mg, 13.6 mmol) were then suspended into a
mixture of acetic acid (5 mL) and dichloroethane (15
mL), and heated at 95 8C for 4 h. Additional ammoni-
um acetate (150 mg, 1.9 mmol) was added, and the
mixture was heated at 100 8C for another hour, cooled
Laboratories, Inc., and were within 9
theoretical values. Column chromatography was carried
out on EM Science silica gel 66 (230ꢀ400 mesh).
/
0.4% of the
/

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249
Table 2
In vitro activity of 5-arylamino-pyridopyrimidines (13) and 5-ethers (14ꢀ
/
15)
to room temperature and partitioned between dichlor-
omethane and sufficient saturated aqueous sodium
bicarbonate to keep the aqueous phase basic to litmus.
The aqueous phase and insoluble solids were extracted
4.2. 5-Methylsulfanyl-7-(6-morpholin-4-yl-pyridin-3-yl)-
pyrido[2,3-d]pyrimidin-4-ylamine (8)
6-Amino-4-methylsulfanyl-6?-morpholin-4-yl-[2,3?]bi-
pyridinyl-5-carbonitrile (5a) (535 mg, 1.63 mmol) and
ammonium sulphate (40 mg, 0.3 mmol) were suspended
in triethyl orthoformate (10 mL) and heated at 140 8C
for 1 h. The mixture was cooled to room temperature,
treated with 2 M ammonia in ethanol (5 mL, 10 mmol),
and stirred for 5 h. Hexanes (5 mL) was added and the
resulting yellow powder was collected by filtration and
rinsed with ether (462 mg).
with dichloromethane (4ꢃ) and the remaining solids
/
were discarded. The combined organic phases were
dried (Na2SO4) and concentrated to give the title
1
compound as a yellow solid (538 mg, 33% yield). H-
NMR (DMSO-d6): d 8.90 (d, Jꢂ/3 Hz, 1H), 8.23 (dd,
Jꢂ9 Hz/3 Hz, 1H), 6.98 (s, 1H), 6.93 (d, Jꢂ
/
/9 Hz, 1H),
6.83 (s, 2H), 3.71 (m, 4H), 3.57 (m, 4H), 2.65 (s, 3H).
This intermediate was then suspended into o-dichlor-
obenzene (6 mL), heated at 160 8C for 3.5 h, and cooled
to room temperature. 50% Ether in dichloromethane (6
mL) was added and the resulting brown solid was
collected by filtration. The filtrate was concentrated
and diluted with ether (5 mL) to provide a second crop
of product. A third crop was obtained by trituration
with hexanes. The combined crude solids were combined
(407 mg, 70%) and used without further purification.
Table 3
In vivo activity of selected pyridopyrimidines
Compound Rat carrageenan hyperalgesia ED50 (mmol kgꢁ1), i.p. a
10d
10e
10f
12c
12h
13d
13e
14b
15
30 *
NS@30 b
10 **
30 *
1H-NMR (DMSO-d6): d 9.06 (d, Jꢂ
1H), 8.42 (dd, Jꢂ9 Hz/2 Hz, 1H), 7.67 (s, 1H), 7.64 (bs,
2H), 6.99 (d, Jꢂ9 Hz, 1H), 3.73 (m, 4H), 3.62 (m, 4H),
2.83 (s, 3H).
/
2 Hz, 1H), 8.43 (s,
NS@30
ꢀ30 **
/
/
30 **
NS@30 c
NS@30
/
a
Values were obtained with six animals at each dose. ED50s were
calculated as the dose giving half maximal effect.
4.3. 5-Methanesulfonyl-7-(6-morpholin-4-yl-pyridin-3-
yl)-pyrido[2,3-d]pyrimidin-4-ylamine (9)
b
Not significant at 30 mmol kgꢁ1
.
c
Compound administered subcutaneously.
* P B0.01.
** P B0.05.
5-Methylsulfanyl-7-(6-morpholin-4-yl-pyridin-3-yl)-
pyrido[2,3-d]pyrimidin-4-ylamine (8) (404 mg, 1.14
/
/

250
G.A. Gfesser et al. / European Journal of Medicinal Chemistry 38 (2003) 245ꢀ252
/
mmol) was dissolved into a mixture of dichloromethane
(25 mL) and methanol (20 mL). Saturated aqueous
sodium bicarbonate (5 mL) and a solution of Oxone†
(1400 mg, 2.28 mmol) in water (10 mL) were added
sequentially, and the resulting heterogeneous mixture
was vigorously stirred for 25 min before being parti-
tioned between chloroform and water. The mixture was
organic phases were concentrated and chromatographed
on silica with 50% ethyl acetateꢀhexanes to give the title
compound (4130 mg, 73%). 1H-NMR (DMSO-d6): d
8.82 (d, Jꢂ2 Hz, 1H), 8.18 (dd, Jꢂ9 Hz/2 Hz, 1H),
6.89 (d, Jꢂ9 Hz, 1H), 6.63 (s, 1H), 6.46 (bs, 2H), 3.71
/
/
/
/
(m, 4H), 3.54 (m, 4H), 3.39 (m, 4H), 1.62 (m, 6H).
worked up as usual to yield a crude yellowꢀ
powder (328 mg, 74%) which was used without further
purification. 1H-NMR (DMSO-d6): d 9.05 (d, Jꢂ
2 Hz,
1H), 8.60 (s, 1H), 8.42 (dd, Jꢂ9 Hz/2 Hz, 1H), 8.37 (s,
1H), 8.33 (bs, 2H), 7.04 (d, Jꢂ9 Hz, 1H), 3.72 (m, 4H),
3.66 (m, 4H), 3.64 (s, 3H).
/
brown
4.5.2. 7-(6-Morpholin-4-yl-pyridin-3-yl)-5-piperidin-1-
yl-pyrido[2,3-d]pyrimidin-4-ylamine (12b)
/
6?-Amino-6ƒ-morpholin-4-yl-3,4,5,6-tetrahydro-2H-
/
[1,4?;2?,3ƒ]terpyridine-5?-carbonitrile (5b, RNR?ꢂ
/piper-
/
idinyl) (3740 mg, 10.26 mmol) and ammonium sulphate
(300 mg, 2.3 mmol) were refluxed in triethyl orthofor-
mate (100 mL) for 3 h. The reaction mixture was cooled
to room temperature, treated with 2.0 M ammonia in
ethanol, and stirred for 3 h. Hexanes was added and the
resulting powder was collected by filtration and dried
under vacuum (3640 mg).
4.4. Representative procedure for the preparation of
monosubstituted amines
4.4.1. N5-Cyclohexyl-7-(6-morpholin-4-yl-pyridin-3-yl)-
pyrido[2,3-d]pyrimidine-4,5-diamine (10a)
This intermediate was then suspended in THF (25
mL), treated with 1 M sodium methoxide in methanol
(50 mL), refluxed for 2.5 h, and cooled to room
temperature. The reaction mixture was neutralized
with 1 M aqueous HCl and extracted with dichloro-
methane. The combined extractions were dried
(MgSO4), concentrated, and chromatographed with a
5-Methanesulfonyl-7-(6-morpholin-4-yl-pyridin-3-yl)-
pyrido[2,3-d]pyrimidin-4-ylamine (9) (270 mg, 0.70
mmol) and cyclohexylamine (400 mL, 3.50 mmol) were
dissolved into DMSO (7 mL) and heated at 100 8C for
40 min, then at 130 8C for another hour. The reaction
mixture was cooled to room temperature, partitioned
between dichloromethane and water, and worked up as
usual. The organic phases were concentrated and
gradient of 2.5ꢀ5% (5% aqueous ammonium hydroxide
/
in ethanol)/dichloromethane to afford the title com-
pound (3360 mg, 83%). 1H-NMR (DMSO-d6): d 9.02 (d,
chromatographed on silica with a gradient of 2ꢀ
methanolꢀdichloromethane to give a yellow powder
(131 mg, 46%). H-NMR (CDCl3): d 8.69 (d, Jꢂ
1H), 8.10 (m, 1H), 7.55 (bs, 1H), 6.67 (d, Jꢂ7 Hz, 1H),
6.62 (s, 1H), 3.83 (m, 4H), 3.60 (m, 4H), 3.49 (m, 1H),
2.04 (m, 2H), 1.79 (m, 2H), 1.66 (m, 1H), 1.25ꢀ1.50 (m,
5H).
/
8%
/
1
Jꢂ
1H), 8.08 (s, 1H), 7.96 (s, 1H), 7.54 (s, 1H), 6.97 (d, Jꢂ
Hz, 1H), 3.72 (m, 4H), 3.60 (m, 4H), 3.32 (m, 2H), 2.81
(m, 2H), 1.65ꢀ1.88 (m, 6H).
/
3 Hz, 1H), 8.40 (dd, Jꢂ9 Hz/3 Hz, 1H), 8.38 (s,
/
/2 Hz,
/9
/
/
/
4.6. Representative procedure for the preparation of
anilines
4.5. Representative procedure for the preparation of
disubstituted amines
4.5.1. 6?Amino-6ƒ-morpholin-4-yl-3,4,5,6-tetrahydro-2H-
4.6.1. 7-(6-morpholin-4-yl-pyridin-3-yl)-N5-phenyl-
pyrido[2,3-d]pyrimidine-4,5-diamine (13a)
[1,4?;2?,3ƒ]terpyridine-5?-carbonitrile (5b, RNR?ꢂ
/
piperidinyl)
2-(Bis-methylsulfanyl-methylene)-malononitrile
5-Methanesulfonyl-7-(6-morpholin-4-yl-pyridin-3-yl)-
pyrido[2,3-d]pyrimidin-4-ylamine (9) (270 mg, 0.7
mmol) and aniline (320 mL, 3.5 mmol) were suspended
in THF (7 mL) and treated with potassium hydride in
mineral oil (ca. 100 mg, 2.5 mmol). After 40 min the
reaction mixture was partitioned between pH 6 aqueous
potassium phosphate buffer (10 mL) and dichloro-
methane, and worked up as usual. The organic phases
were concentrated and chromatographed on silica with a
(6)
(3400 mg, 20 mmol) and piperidine (2.0 mL, 20 mmol)
were refluxed in dichloromethane (80 mL) for 90 min.
The reaction mixture was brought to room temperature
and concentrated under vacuum to provide 11 (4030
mg), which was used without further purification.
This intermediate, 1-(6-morpholin-4-yl-pyridin-3-yl)-
ethanone (3a) (3090 mg, 15.0 mmol), and lithium tert-
butoxide (2400 mg, 30.0 mmol) were dissolved into
DMSO (30 mL) and stirred at room temperature for 2.5
h. Ammonium acetate (11.56 g, 150 mmol) and acetic
acid (80 mL) were added and the resulting mixture was
refluxed for 3 h, cooled to room temperature, parti-
tioned between 1 M aqueous sodium hydroxide (1 L)
and dichloromethane, and worked up as usual. The
gradient of 2ꢀ
/
6% methanolꢀdichloromethane to give an
/
impure yellow powder (119 mg, 42%) which could be
1
recrystallized from ethyl acetateꢀ
(CD3OD/CDCl3): d 8.35 (d, Jꢂ2 Hz, 1H), 8.16 (s, 1H),
7.69 (m, 1H), 7.37 (dd, Jꢂ8 Hz/8 Hz, 2H), 7.11 (t, Jꢂ
Hz, 1H), 7.00 (d, Jꢂ8 Hz, 2H), 6.67 (d, Jꢂ9 Hz, 1H),
6.35 (bs, 1H), 3.82 (m, 4H), 3.58 (m, 4H).
/chloroform. H-NMR
/
/
/8
/
/

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251
Table 4
1H NMR data for compounds 10, 12ꢀ
/
15
10a (CDC13) d 1.25ꢀ
Hz, 1H), 7.55 (s, 1H), 8.10 (m, 1H), 8.69 (d, Jꢂ
10b (CD3OD/CDC13) d 1.50ꢀ1.88 (m, 12H), 1.92ꢀ2.05 (m, 2H), 3.64 (m, 4H), 3.73 (m, 1H), 3.85 (m, 4H), 6.65 (s, 1H), 6.77 (d, Jꢂ
8.09ꢀ8.24 (m, 2H), 8.72 (d, Jꢂ2 Hz, 1H).
10c (CD3OD/CDC13) d 1.00ꢀ1.39 (m, 5H), 1.65ꢀ
1H), 8.03ꢀ8.26 (m, 2H), 8.75 (d, Jꢂ2 Hz, 1H).
10d (CD3OD/CDC13) d 3.61 (m, 4H), 3.83 (m, 4H), 4.57 (s, 2H), 6.61 (s, 1H), 6.72 (d, Jꢂ
1H), 8.12 (s, 1H), 8.59 (d, Jꢂ3 Hz, 1H).
10e (CD3OD/CDC13) d 3.64 (m, 4H), 3.84 (mm, 4H), 4.81 (s, 2H), 6.73 (s, 1H), 6.74 (d, Jꢂ
Hz/1 Hz, 1H), 7.26 (dd, Jꢂ5 Hz/1 Hz, 1H), 8.04 (m, 1H), 8.20 (s, 1H), 8.63 (d, Jꢂ2 Hz, 1H).
10f (CD3OD/CDC13) d 3.62 (m, 4H), 3.84 (m, 4H), 4.68 (s, 2H), 6.56 (s, 1H), 6.73 (d, Jꢂ9 Hz, 1H), 7.37 (dd, Jꢂ
Hz/2 Hz/2 Hz, 1H), 7.94 (dd, Jꢂ9 Hz/3 Hz, 1H), 8.14 (s, 1H), 8.50 (dd, Jꢂ5 Hz/2 Hz, 1H), 8.58 (d, Jꢂ3 Hz, 1H), 8.64 (d, Jꢂ
10g (CD3OD/CDC13) d 3.11 (t, 2H), 3.60ꢀ3.68 (m, 6H), 3.85 (t, Jꢂ7 Hz, 4H), 6.58 (s, 1H), 6.75 (d, Jꢂ9 Hz, 1H), 7.32 (m, 1H), 7.69 (m, 1H), 8.04
(dd, Jꢂ9 Hz/2 Hz, 1H), 8.10 (s, 1H), 8.45 (m, 1H), 8.51 (d, Jꢂ2 Hz, 1H), 8.66 (d, Jꢂ2 Hz, 1H).
10h (Acetone/DMSO-d6) d 3.48 (m, 4H), 3.63 (m, 4H), 4.68 (s, 2H), 6.75 (d, Jꢂ6 Hz, 1H), 6.91 (t, Jꢂ6 Hz, 1H), 7.01 (m, 2H), 7.30 (d, Jꢂ
1H), 7.35 (s, 1H), 7.60 (d, Jꢂ6 Hz, 1H), 7.80 (s, 1H), 8.24 (dd, Jꢂ9 Hz/3 Hz, 1H), 8.88 (d, Jꢂ3 Hz, 1H).
10i (Acetone-d6) d 3.18 (t, Jꢂ6 Hz, 2H), 3.55 (m, 4H), 3.72 (m, 6H), 6.79 (d, Jꢂ9 Hz, 1H), 6.85 (s, 1H), 7.00 (m, 1H), 7.08 (m, 1H), 7.28 (s, 1H),
7.35 (d, Jꢂ9 Hz, 1H), 7.54 (d, Jꢂ9 Hz, 1H), 7.95 (bs, 1H), 8.13 (d, Jꢂ9 Hz, 1H), 8.84 (s, 1H).
12b (DMSO-d6) d 1.65ꢀ1.88 (m, 6H), 2.81 (m, 2H), 3.32 (m, 2H), 3.60 (m, 4H), 3.72 (m, 4H), 6.97 (d, Jꢂ
8.08 (s, 1H,NH2), 8.38 (s, 1H), 8.40 (dd, Jꢂ9 Hz/3 Hz, 1H), 9.02 (d, Jꢂ3 Hz, 1H).
12c (DMSO-d6) d 1.59ꢀ1.72 (m, 4H), 1.72ꢀ1.84 (m, 4H), 3.3ꢀ3.52 (m, 4H), 3.59 (m, 4H), 3.72 (m, 4H), 6.97 (d, Jꢂ
2H, NH2), 8.32 (s, 1H), 8.37 (dd, Jꢂ9 Hz/2 Hz, 1H), 8.99 (d, Jꢂ2 Hz, 1H).
12d (DMSO-d6) d 1.54ꢀ1.66 (m, 6H), 1.66ꢀ1.79 (m, 4H), 3.35ꢀ3.58 (m, 4H), 3.58 (m, 4H), 3.72 (m, 4H), 6.97 (D, Jꢂ
(s, 2H, NH2), 8.30 (s, 1H), 8.38 (dd, Jꢂ9 Hz/3 Hz, 1H), 8.99 (d, Jꢂ3 Hz, 1H).
12e (DMSO-d6) d 0.90 (t, Jꢂ7 Hz, 3H), 1.24ꢀ1.49 (m, 7H), 1.80ꢀ1.90 (m, 2H), 2.73ꢀ
6.98 (d, Jꢂ9 Hz, 1H), 7.55 (s, 1H, NH2), 8.38 (s, 1H) 8.40 (dd, Jꢂ9 Hz/2 Hz, 1H), 9.02 (d, Jꢂ
12f (DMSO-d6) d 0.83 (t, Jꢂ7 Hz, 6H), 1.15ꢀ1.30 (m, 4H), 1.30ꢀ1.58 (m, 4H), 2.98ꢀ3.17 (m, 2H), 3.28ꢀ
6.99 (d, Jꢂ9 Hz, 1H), 7.66 (s, 1H), 8.03 (s, 1H, NH2), 8.32 (s, 1H, NH2), 8.36 (s, 1H), 8.40 (dd, Jꢂ
12g (DMSO-d6) d 1.04ꢀ1.96 (m, 10H), 2.82 (s, 3H), 3.12 (m, 1H), 3.59 (m, 4H), 3.72) (m, 4H), 6.98 (d, Jꢂ
NH2), 8.26 (s, 1H, NH2), 8.36 (s, 1H), 8.40 (dd, Jꢂ9 Hz/2 Hz, 1H), 9.02 (d, Jꢂ2 Hz, 1H).
12h (DMSO-d6) d 2.92 (m, 1H), 3.21 (m, 1H), 3.57ꢀ3.78 (m, 10H), 4.26 (d, Jꢂ15 Hz, 1H), 4.42 (d, Jꢂ
4H), 7.64 (s, 1H), 7.96 (s, 2H, NH2), 8.40 (dd, Jꢂ9 Hz/2 Hz, 1H), 8.41 (s, 1H), 9.02 (d, Jꢂ2 Hz, 1H).
12i (DMSO-d6) d 2.81 (s, 3H), 3.60 (m, 4H), 3.72 (m, 4H), 4.35 (d, Jꢂ14 Hz, 1H), 4.58 (d, Jꢂ14 Hz, 1H), 6.97 (d, Jꢂ
Hz/5 Hz, 1H), 7.53 (s, 1H), 7.71 (ddd, Jꢂ8 Hz/2 Hz/2 Hz, 1H), 8.11 (s, 1H, NH2), 8.26 (s, 1H, NH2), 8.34 (dd, Jꢂ9 Hz/3 Hz, 1H) 8.38 (s, 1H),
8.14 (dd, Jꢂ5 Hz/2 Hz, 1H), 8.55 (d, Jꢂ2 Hz, 1H), 8.95 (d, Jꢂ2 Hz, 1H).
13a (CD3OD/CDCl3) d 3.58 (m, 4H), 3.82 (m, 4H) 6.35 (s, 1H), 6.67 (d, Jꢂ9 Hz, 1H), 7.00 (d, Jꢂ
Hz/8 Hz, 2H), 7.69 (m, 1H), 8.16 (s, 1H), 8.35 (d, Jꢂ2 Hz, 1H).
13b (CD3OD/CDCl3) d 3.58 (m, 4H), 3.82 (m, 4H), 6.10 (s, 1H), 6.67 (d, Jꢂ
(dd, Jꢂ8 Hz/8 Hz, 1H), 7.62ꢀ7.71 (m, 2H), 8.20 (s, 1H), 8.32 (d, Jꢂ2Hz, 1H)
13c (CD3OD/CDCl3) d 3.60 (m, 4H), 3.82 (m, 4H), 6.13 (s, 1H), 6.69 (d, Jꢂ9 Hz, 1H), 7.40ꢀ
2H), 8.34 (d, Jꢂ2 Hz, 1H).
13d (CDCl3) d 3.30 (s, 3H), 3.64 (m, 4H), 3.82 (m, 4H), 6.02 (bs, 1H, NH2), 6.72 (d, Jꢂ
7.32 (dd, Jꢂ8 Hz/8 Hz, 2H), 7.45 (s, 1H), 7.81 (bs, 1H, NH2), 8.51 (dd, Jꢂ9 Hz/3 Hz, 1H), 8.69 (s, 1H), 8.75 (d, Jꢂ
13e (DMSO-d6) d 3.04ꢀ3.3 (m, 2H), 3.59 (m, 4H), 3.71 (m, 4H), 3.96ꢀ4.21 (m, 2H), 6.45 (d, Jꢂ8 Hz, 1H), 6.88 (dd, Jꢂ8 Hz/8 Hz, 1H), 6.97 (d,
Jꢂ9 Hz, 1H), 7.00 (dd, Jꢂ8 Hz/8 Hz, 1H), 7.29 (d, Jꢂ8 Hz, 1H), 7.44 (bs, 1H, NH2), 7.79 (s, 1H), 7.91 (bs, 1H, NH2), 8.37 (dd, Jꢂ9 Hz/3
Hz, 1H), 8.43 (s, 1H), 8.99 (d, Jꢂ3 Hz, 1H).
14a (DMSO-d6) d 1.05 (t, Jꢂ7 Hz, 3H), 1.92 (qt, Jꢂ
(s, 1H, NH2), 7.50 (s, 1H), 8.06 (s, 1H, NH2), 8.40 (s, 1H), 8.42 (dd, Jꢂ
14b (DMSO-d6) d 1.27ꢀ1.77 (m, 8H), 2.00ꢀ2.11 (m, 2H), 3.59 (m, 4H), 3.72 (m, 4H), 5.08 (m, 1H), 6.98 (d, Jꢂ
1H), 8.07 (s, 1H, NH2), 8.40 (s, 1H), 8.42 (dd, Jꢂ9 Hz/3 Hz, 1H), 9.06 (d, Jꢂ3 Hz, 1H).
14c (CD3OD/CDCl3) d 3.67 (m, 4H), 3.86 (m, 4H), 5.47 (s, 2H), 6.80 (d, Jꢂ9 Hz, 1H), 7.32 (s, 1H), 7.50 (dd, Jꢂ
(dd, Jꢂ9 Hz/2 Hz, 1H), 8.58 (s, 1H), 8.70 (m, 1H), 8.79 (d, Jꢂ2 Hz, 1H), 8.87 (d, Jꢂ2 Hz, 1H).
15 (CD3OD/CDCl3) d 3.61 (m, 4H), 3.82 (m, 4H), 6.74 (d, Jꢂ9 Hz, 1H), 6.86 (s, 1H), 7.28 (d, Jꢂ8 Hz, 2H), 7.44 (t, Jꢂ
Hz/8 Hz, 2H), 8.34 (dd, Jꢂ9 Hz/3 Hz, 1H), 8.55 (d, Jꢂ3 Hz, 1H), 8.59 (s, 1H).
/
1.50 (m, 5H), 1.66 (m, 1H), 1.79 (m, 2H), 2.04 (m, 2H), 3.49 (m, 1H), 3.60 (m, 4H), 3.83 (m, 4H), 6.62 (s, 1H), 6.67 (d, Jꢂ
/7
/
2 Hz, 1H).
/
/
/9 Hz, 1H),
/
/
/
/
1.92 (m, 6H), 3.15 (d, Jꢂ
/
7 Hz, 2H), 3.61 (m, 4H), 3.84 (m, 4H), 6.70 (s, 1H), 6.75 (d, Jꢂ
9 Hz, 1H), 7.31ꢀ7.35 (m, 4H), 8.05 (dd, Jꢂ9 Hz/3 Hz,
9 Hz, 1H), 7.00 (dd, Jꢂ5 Hz/4 Hz, 1H), 7.09 (dd, Jꢂ
8 Hz/5 Hz, 1H), 7.84 (ddd, Jꢂ
/
9 Hz,
/
/
/
/
/
/
/
/
/4
/
/
/
/
/
8
/
/
/
/2 Hz, 1H).
/
/
/
/
/
/
/
/
/
6 Hz,
/
/
/
/
/
/
/
/
/
/9 Hz, 1H), 7.54 (s, 1H), 7.96 (s, 1H, NH2),
/
/
/
/
/
/9 Hz, 1H), 7.51 (s, 1H), 7.95 (s,
/
/
/
/
/
/9 Hz, 1H), 7.54 (s, 1H), 7.91
/
/
/
/
/
/
2.86 (m, 2H), 3.29ꢀ
2Hz, 1H).
3.46 (m, 2H), 3.60 (m, 4H), 3.73 (m, 4H),
9 Hz/2 Hz, 1H), 9.02 (d, Jꢂ2 Hz, 1H).
9 Hz, 1H), 7.61 (s, 1H), 7.95 (s, 1H,
/
3.4 (m, 2H), 3.59 (m, 4H), 3.72 (m, 4H),
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
15 Hz, 1H), 6.99 (d, Jꢂ
/
9 Hz, 1H), 7.22 (s,
/
/
/
/
/
9 Hz, 1H), 7.31 (dd, Jꢂ8
/
/
/
/
/
/
/
/
8 Hz, 2H), 7.11 (t, Jꢂ
9 Hz, 1H), 7.02 (d, Jꢂ8 Hz, 1H), 7.15 (dd, Jꢂ
7.45 (m, 2H), 7.65 (m, 1H), 8.20 (s, 1H), 8.22ꢀ8.31 (m,
/
8 Hz, 1H), 7.37 (dd, Jꢂ8
/
/
/
/
/8 Hz/8 Hz, 1H), 7.49
/
/
/
/
/
/
/
/
9 Hz, 1H), 6.97 (d, Jꢂ
/
8 Hz, 2H), 7.07 (t, Jꢂ
/
8 Hz, 1H),
/
/
/
2 Hz, 1H).
/
/
/
/
/
/
/
/
/
/
/
7 Hz/7 Hz, 2H), 3.59 (m, 4H), 3.72 (m, 4H), 4.40 (t, Jꢂ
9 Hz/3 Hz, 1H), 9.06 (d, Jꢂ3 Hz, 1H).
9 Hz, 1H), 7.35 (s, 1H, NH2), 7.53 (s,
/
7 Hz, 2H), 6.98 (d, Jꢂ9 Hz, 1H), 7.36
/
/
/
/
/
/
/
/
/
/
8 Hz/5 Hz, 1H), 7.94 (m, 1H), 8.50
/
/
/
/
/
/
8 Hz, 1H), 7.58 (dd, Jꢂ8
/
/
/
4.7. Representative procedure for the preparation of alkyl
ethers
mg, 0.50 mmol), cyclohexanol (260 mL, 2.5 mmol), and
sodium hydride in mineral oil (ca. 70 mg, 3 mmol) was
suspended in a mixture of THF (5 ml) and DMSO (3
mL). After the mixture was refluxed overnight, it was
cooled to room temperature, diluted with water, filtered,
worked up as usual, and concentrated to provide the
title compound (144 mg, 70%). 1H-NMR (DMSO-d6): d
4.7.1. Cyclohexyloxy-7-(6-morpholin-4-yl-pyridin-3-yl)-
pyrido[2,3-d]pyrimidin-4-ylamine (14b)
A mixture of 5-methylsulfanyl-7-(6-morpholin-4-yl-
pyridin-3-yl)-pyrido[2,3-d]pyrimidin-4-ylamine (8) (177

252
G.A. Gfesser et al. / European Journal of Medicinal Chemistry 38 (2003) 245ꢀ252
/
9.06 (d, Jꢂ
8.40 (s, 1H), 8.07 (bs, 1H), 7.53 (s, 1H), 7.35 (bs, 1H),
6.98 (d, Jꢂ9 Hz, 1H), 5.08 (m, 1H), 3.72 (m, 4H), 3.59
(m, 4H), 2.00ꢀ2.11 (m, 2H), 1.27ꢀ1.77 (m, 8H).
/
3 Hz, 1H), 8.42 (dd, Jꢂ
/
9 Hz/3 Hz, 1H),
References
[1] M. Williams, M.F. Jarvis, Biochem. Pharmacol. 59 (2000)
1173.
/
/
/
[2] G.W. Bong, S. Rosengren, G.J. Firestein, Clin. Invest. 98 (1996)
2779.
4.7.2. 7-(6-morpholin-4-yl-pyridin-3-yl)-5-phenoxy-
pyrido[2,3-d]pyrimidin-4-ylamine (15)
[3] E.A. Kowaluk, M.F. Jarvis, Exp. Opin. Invest. Drug 9 (2000)
551.
[4] P. Marangos, Med. Hypotheses 32 (1990) 45.
[5] K. Mullane, M. Young, Drug Dev. Res. 23 (1993)
336.
A suspension of 5-methanesulphonyl-7-(6-morpholin-
4-yl-pyridin-3-yl)-pyrido[2,3-d]pyrimidin-4-ylamine (9)
(386 mg, 1.0 mmol) and phenol (471 mg, 5.0 mmol) in
THF (10 mL) was briefly sonicated to affect small
particle size. Potassium hydride in mineral oil (ca. 200
mg, 5 mmol) was added to the rapidly stirred suspen-
sion. Bubbling quickly ensued. After 15 min the reaction
mixture was partitioned between pH 6 aqueous potas-
sium phosphate buffer (40 mL) and dichloromethane
(40 mL), and worked up as usual. The organic phases
were concentrated and chromatographed on silica with a
[6] J.R.S. Arch, E.A. Newsholme, Essays Biochem. 14 (1978)
82.
[7] M.F. Jarvis, H. Yu, K. Kohlhaas, K. Alexander, C.-H. Lee, M.
Jiang, S.S. Bhagwat, M. Williams, E.A. Kowaluk, J. Pharmacol.
Exp. Ther. 295 (2000) 1156.
[8] E.A. Kowaluk, J. Mikusa, C.T. Wismer, C.Z. Zhu, E. Schweitzer,
J.J. Lynch, C.-H. Lee, M. Jiang, S.S. Bhagwat, A. Gomtsyan, J.
McKie, B.F. Cox, J. Polakowski, G. Reinhart, M. Williams, M.F.
Jarvis, J. Pharmacol. Exp. Ther. 295 (2000) 1165.
[9] M. Cowart, C.-H. Lee, G.A. Gfesser, E.K. Bayburt, S.S.
Bhagwat, A.O. Stewart, H. Yu, K.L. Kohlhaas, S. McGaraughty,
C.T. Wismer, J. Mikusa, C. Zhu, K.M. Alexander, M.F. Jarvis,
E.A. Kowaluk, Bioorg. Med. Chem. 11 (2001) 83.
[10] C.-H. Lee, M. Jiang, M. Cowart, G. Gfesser, R. Perner, K.H.
Kim, Y.G. Gu, M. Williams, M.F. Jarvis, E.A. Kowaluk, A.O.
Stewart, S.S. Bhagwat, J. Med. Chem. 44 (2001)
2133.
gradient of 0ꢀ
/
6% methanolꢀdichloromethane to give
/
the title compound as an impure yellow powder (263
mg, 65%) which could be recrystallized from ethyl
acetateꢀ
8.59 (s, 1H), 8.55 (d, Jꢂ
Hz/3 Hz, 1H), 7.58 (dd, Jꢂ
8 Hz, 1H), 7.28 (d, Jꢂ8 Hz, 2H), 6.86 (s, 1H), 6.74 (d,
Jꢂ9 Hz, 1H), 3.82 (m, 4H), 3.61 (m, 4H) (Table 4).
/
chloroform. 1H-NMR (CD3OD/CDCl3):
d
/
3 Hz, 1H), 8.34 (dd, Jꢂ
/
9
/
8 Hz/8 Hz, 2H), 7.44 (t, Jꢂ
/
/
[11] Y. Tominaga, M. Kawabe, A. Hosomi, J. Heterocyclic Chem. 24
(1987) 1325.
/