Potent and selective inhibitors of PDGF receptor phosphorylation. 2. Synthesis, structure activity relationship, improvement of aqueous solubility, and biological effects of 4-[4-(N-substituted (thio)carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazoline derivatives

Article abstract of DOI:10.1021/jm0201114

4-[4-(N-Substituted (thio)carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazoline derivatives such as KN1022 are potent inhibitors of the phosphorylation of platelet derived growth factor receptor (PDGFR). Structure activity relationships in the (thio)urea moiety, the phenyl ring itself, the linker between these two moieties, and the piperazine moiety were investigated. The role of the linker was found to be quite different, where ureas yielded decreasing activity, while thioureas provided increasing activity. Cyanoguanidine as a bioisostere of thiourea and related dicyanovinyl or nitrovinyl groups were not suitable for potent activity. A hydrogen atom on the (thio)urea moiety was essential for activity. Stereochemistry was also important for inhibition of PDGFR phosphorylation. Through the modification of these moieties, benzylthiourea analogues with a small substituent on the 4-position and the 3,4-methylenedioxy group (KN734/CT52923) were found to be optimal for selective and potent activity. Replacement of the phenyl ring by heterocycles improved aqueous solubility without loss of activity and kinase selectivity. Introduction of a methyl group on 5-position of the piperazine ring and replacement by homopiperazine reduced inhibitory activity. An efficient synthetic method was also developed for 2-pyridylurea-containing analogues, via carbonylation of 2-aminopyridine with N,N′-carbonyldiimidazole. A potent analogue, KN734, inhibited smooth muscle cell proliferation and migration induced by platelet derived growth factor-BB (PDGF-BB) and suppressed neointima formation following balloon injury in rat carotid artery by oral administration. Therefore, 4-[4-(N-substituted (thio)carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazoline derivatives may be expected to have potential as therapeutic agents for the treatment of restenosis.

Full text of DOI:10.1021/jm0201114

J . Med. Chem. 2002, 45, 4513-4523
4513
P oten t a n d Selective In h ibitor s of P DGF Recep tor P h osp h or yla tion . 2.
Syn th esis, Str u ctu r e Activity Rela tion sh ip , Im p r ovem en t of Aqu eou s Solu bility,
a n d Biologica l Effects of 4-[4-(N-Su bstitu ted
(th io)ca r ba m oyl)-1-p ip er a zin yl]-6,7-d im eth oxyqu in a zolin e Der iva tives
Kenji Matsuno,*,† Takao Nakajima,† Michio Ichimura,† Neill A. Giese,‡ J in-Chen Yu,‡ Nathalie A. Lokker,‡
J unko Ushiki,† Shin-ichi Ide,† Shoji Oda,† and Yuji Nomoto†
Kyowa Hakko Kogyo Co., Ltd., Pharmaceutical Research Institute, Shimotogari 1188, Nagaizumi-cho, Sunto-gun,
Shizuoka, 411-8731, J apan, and Millennium Pharmaceuticals, Inc., 256 E. Grand Avenue,
South San Francisco, California 94080
Received March 11, 2002
4-[4-(N-Substituted (thio)carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazoline derivatives such
as KN1022 are potent inhibitors of the phosphorylation of platelet derived growth factor receptor
(PDGFR). Structure activity relationships in the (thio)urea moiety, the phenyl ring itself, the
linker between these two moieties, and the piperazine moiety were investigated. The role of
the linker was found to be quite different, where ureas yielded decreasing activity, while
thioureas provided increasing activity. Cyanoguanidine as a bioisostere of thiourea and related
dicyanovinyl or nitrovinyl groups were not suitable for potent activity. A hydrogen atom on
the (thio)urea moiety was essential for activity. Stereochemistry was also important for
inhibition of PDGFR phosphorylation. Through the modification of these moieties, benzylth-
iourea analogues with a small substituent on the 4-position and the 3,4-methylenedioxy group
(KN734/CT52923) were found to be optimal for selective and potent activity. Replacement of
the phenyl ring by heterocycles improved aqueous solubility without loss of activity and kinase
selectivity. Introduction of a methyl group on 5-position of the piperazine ring and replacement
by homopiperazine reduced inhibitory activity. An efficient synthetic method was also developed
for 2-pyridylurea-containing analogues, via carbonylation of 2-aminopyridine with N,N′-
carbonyldiimidazole. A potent analogue, KN734, inhibited smooth muscle cell proliferation and
migration induced by platelet derived growth factor-BB (PDGF-BB) and suppressed neointima
formation following balloon injury in rat carotid artery by oral administration. Therefore, 4-[4-
(N-substituted (thio)carbamoyl)-1-piperazinyl]-6,7-dimethoxyquinazoline derivatives may be
expected to have potential as therapeutic agents for the treatment of restenosis.
In tr od u ction
peutic potential in the treatment of these proliferative
disorders.
Platelet derived growth factor (PDGF) is known to act
as a potent mitogen and chemotactic factor for various
cells such as fibroblasts, smooth muscle cells (SMCs),
mesenchymal cells, and brain glial cells.1-4 Abnormal
PDGF-induced cell proliferation has been proposed to
lead to proliferative disorders such as atherosclerosis,
restenosis following percutaneous transluminal coro-
nary angioplasty (PTCA), glomerulonephritis, glomeru-
losclerosis, liver cirrhosis, pulmonary fibrosis, and
cancer.5-15 Additionally, PDGF and its receptor (PDG-
FR) are also upregulated in these proliferative dis-
orders. Within restenosis lesions, PDGF plays a major
role in the vascular response to injury.16-20 PDGF
receptor (PDGFR) is known to possess a tyrosine kinase
activity and is autophosphorylated in the course of
receptor activation. Therefore, an inhibitor of PDGFR
phosphorylation would be expected to possess a thera-
Recently, 4-[4-(N-substituted (thio)carbamoyl)-1-pip-
erazinyl]-6,7-dimethoxyquinazoline derivatives such as
KN1022 or 1a -1f (Table 1) were found to be selective
inhibitors for the PDGFR phosphorylation,21-23 and
initial structure activity relationships (SARs) focused
on 4-nitrophenylcarbamoyl moiety have been reported.24
Bulky substitution on the 4-position of the phenyl ring
was generally favorable for the urea analogues, espe-
cially 4-isopropyl, 4-tert-butyl, or 4-phenoxyphenyl.
Thioureas also showed inhibitory activity; however,
SARs were slightly different from the ureas. Bulky
hydrophobic substituents on the 3- or 4-position were
found to be suitable for potent activity, and the potency
of the thiourea analogues was weaker than that of the
corresponding urea analogue.
In this paper, we report further synthesis and the
SARs for inhibition of in vitro â-PDGFR phosphorylation
focused on the (thio)urea moiety, the phenyl ring itself,
the insertion of a linker between these two moieties for
the modification of the distance and orientation of a
phenyl ring relative to the (thio)urea moiety, and
modification of the piperazine moiety. We report at-
* Corresponding author. Present address: Kyowa Hakko Kogyo Co.,
Ltd. Ohtemachi 1-6-1, Chiyoda-ku, Tokyo, 100-8185, J apan. Phone:
+81-3-3282-0064. Fax: +81-3-3284-0407. E-mail: kenji.matsuno@
kyowa.co.jp
† Kyowa Hakko Kogyo Co., Ltd.
‡ Millennium Pharmaceuticals, Inc., formerly COR Therapeutics,
Inc.
10.1021/jm0201114 CCC: $22.00 © 2002 American Chemical Society
Published on Web 08/27/2002

4514 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20
Matsuno et al.
Ta ble 1.
Sch em e 2
no.
R
X
IC50 (µmol/L)
Sch em e 3a
KN1022
NO2
Cl
Cl
O
O
S
O
O
O
O
0.70
1.10
0.79
0.53
0.08
0.03
0.08
1a
1b
1c
1d
1e
1f
Br
iPr
tert-Bu
OPh
Sch em e 1a
a
(a) DPPA, Et3N, dioxane; (b) tert-BuOH, 80 °C; (c) hydrochloric
acid, aqueous Et2O; (d) CDI, Et3N, CH2Cl2; (e) 2.
Curtius rearrangement of the carboxylic azide that was
prepared from carboxylic acid analogues with sodium
azide (method C) or diphenylphosphoryl azide (method
D), or treatment of amines with 4-methoxyphenyl 4-ni-
trophenyl carbonate in acetonitrile,26 followed by addi-
tion of 2 provided the ureas (method E). Treatment of
amines with known carbamoyl chloride 3a 27 in the
presence of triethylamine provided the urea (method F).
Heating amines in N-methylpyrrolidinone (NMP) with
4-nitrophenylcarbamate 3b, which was prepared from
2 and 4-nitrophenylchloroformate in the presence of
triethylamine, also provided the ureas (method G).
Application of method F and G for aniline type amines
was inappropriate because of their low nucleophilicity.
Method B was found to be widely applicable for
synthesis of the ureas. 2-Pyridylisocyanate could not be
prepared by treatment of 2-aminopyridine with phos-
gene since the resulting isocyanate spontaneously dimer-
ized.28 On the other hand, a mixture of 2-aminopyridine
and CDI was warmed to 50 °C in N,N-dimethyforma-
mide (DMF), followed by addition of 2 to provide the
desired 2-pyridylurea analogue 4l as shown in Scheme
2. From this result, we speculate that the reaction
species is N-(2-pyridyl)-1-imidazolecarboxamide. Since
there are limited synthetic procedures to prepare the
2-pyridylureas such as carbamoylation of 2-aminopyri-
dine, this method is quite efficient, especially in the case
of the complex 2-pyridylurea derivatives. The 2-thienyl
analogue 4p was also obtained by method B. For
2-thienyl analogue 4p , since 2-aminothiophene is known
to be unstable,29 deprotection of known 2-tert-butoxy-
carbonylaminothiophene,29 followed by quickly treating
under the condition of method B in the presence of
triethylamine, successfully provided the desired com-
pound 4p as shown in Scheme 3.
a
Method A: R-NCO, solvent. Method B: (i) R-NH2, CDI,
solvent, (ii) 2. Method C: (i) R-COCl, NaN3, Et2O, H2O, 0 °C; (ii)
2, toluene, 70 °C. Method D: (i) R-COOH, diphenylphosphoryl
azide (DPPA), Et3N, toluene; (ii) 70 °C; (iii) 2. Method E: (i) R-NH2,
4-methoxyphenyl 4-nitrophenylcarbonate, MeCN; (ii) 2, DBU.
Method F: 3a , R-NH2, Et3N, DMF. Method G: 3b, R-NH2, NMP,
60 °C. (a) For 3a : triphosgene, Et3N, CH2Cl2, 0 °C, 38%. (b) For
3b: 4-nitrophenylchloroformate, Et3N, CH2Cl2, 75%.
tempts to improve the solubility of analogues without
loss of the inhibitory activity by replacing the phenyl
ring with a heterocyclic ring since the initial lead
compound KN1022 was quite insoluble (Table 7). An
evaluation of kinase selectivity for selected analogues
is also reported. Furthermore, we also report the selec-
tion of analogues for in vivo evaluation by measurement
of plasma drug concentration after oral administration
to Sprague-Dawley rats (SD rats) and the inhibitory
activity on neointima formation in rat carotid artery.
Ch em istr y
General synthetic methods for the ureas 4 are out-
lined in Scheme 1. There are seven methods (methods
A, B, C, D, E, F, G) to prepare analogues 4a -4s from
the known intermediate 4-(1-piperazinyl)-6,7-dimethoxy-
quinazoline (2)25 or the related compounds 3a and 3b.
Method A (condensation of 2 and commercially available
isocyanate) and method B (carbonylation of amine with
N,N′-carbonyldiimidazole (CDI), followed by condensa-
tion with 2) was described in our previous publication.24
The widely used synthetic routes to the thioureas 6
are outlined in Scheme 4. Method H (condensation of 2
and isothiocyanate) and method I (thiocarbonylation of
amine with thiophosgene in the presence of triethyl-
amine, followed by condensation with 2) were described
in the previous publication.24 Treatment of 2 with
thiophosgene gave thiocarbamoyl chloride 5, followed
by condensation with an amine provided the thiourea

Inhibitors of PDGF Receptor Phosphorylation
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20 4515
Sch em e 4a
Table 2 shows the results that the linker between the
phenyl ring and the (thio)urea moiety has a substan-
tially different influence on the inhibitory activity.
Regarding urea derivatives, insertion and extension of
the methylene chain reduced the activity (1c vs 4c, 1d
vs 4e, 1e vs 4f, 1f vs 4h , 4a vs 4j). The bulky 4-sub-
stituent on the phenyl ring was favorable among the
benzylurea series (comparison 4d , 4e, and 4f); however,
the IC50 values were higher than those of the corre-
sponding phenylurea analogues.24 Interestingly, phena-
cyl analogue 4k , which was carbonylated at benzyl
position of the phenethyl group, showed potent activity.
In contrast, for the thiourea derivatives, insertion of
one methylene unit between the thiourea moiety and
phenyl ring (the benzylthioureas) was found to enhance
inhibitory activity with log scale in some substituents.
For instance, comparing chloro analogues, the 4-chlo-
robenzylthiourea (6b, IC50 ) 0.07 µmol/L) showed much
more potent activity than 4-chlorophenylthiourea 1b or
4-chlorobenzylurea 4a . The most suitable place for
substitution was the 4-position by comparison of 6b with
6c and 6d . Further extension of the methylene chain,
4-chlorophenethyl analogue 6m , resulted in reduced
activity. When the linker was cyclopropylmethyl (6n ),
the activity was completely eliminated. Although the
bulky 4-bromo analogue 6e was a potent inhibitor, the
4-methyl analogue (6f, IC50 ) 0.03 µmol/L) and 4-meth-
oxy analogue (6i, IC50 ) 0.10 µmol/L) showed more
potent activity than the bulky 4-isopropyl 6g and
4-phenoxy 6j analogues among the alkyl and alkoxy-
substituted analogues, respectively. From these results,
benzylthioureas with relatively small substituents were
found to be suitable for the potent activity differing from
the phenylthiourea analogues.24 3,4-Dimethoxy ana-
logue 6k was a weak inhibitor; however, bicyclic 3,4-
methylenedioxybenzyl analogue (KN734, IC50 ) 0.09
µmol/L) was found to be more potent than 6k , unlike
the activity of corresponding phenylthioureas described
in our previous report.24 Furthermore, (S)-6l, which is
R-methylated analogue of the benzylthiourea 6a , re-
tained activity, and the enantiomer (R)-6l was a con-
siderably weaker inhibitor. As we have already de-
scribed in a previous biological article,30 the inhibition
mechanism of KN734 was via reversible competition
with ATP with a Ki value of 3 nmol/L. These results
suggest that the chirality of the molecule was recognized
by â-PDGFR and the binding pocket of the inhibitor may
be a narrow cleft with the (R)-methyl group causing
quite unfavorable steric interactions.
a
Method H: R-NCS, solvent. Method I: (i) R-NH2, CSCl2, Et3N,
solvent; (ii) 2. Method J : R-NH2, Et3N, DMF. (a) Thiophosgene,
Et3N, CH2Cl2, 52%.
(method J ). This method was also inappropriate for the
anilines like the carbamoyl chloride 3a .
The cyanoguanidine 10, whose moiety is a well-known
for a bioisostere of thiourea as made famous by cime-
tidine, and the dicyanovinyl 11 and nitrovinyl 12
analogues were obtained by condensation of 7a (or 7b),
8, 9, and amine under heating in the appropriate
solvent, respectively (Scheme 5). 2-Propanol was espe-
cially suitable for this reaction since the substitution
of ethoxy group occurred in ethanol. For all amines
presented in Schemes 1, 4, and 5 where salt forms such
as hydrochloride were used, addition of more than one
equivalent triethylamine for the amine in the reaction
mixture yielded the desired compounds.
The N-methylurea 4t was successfully obtained by
methylation of 1c24 (Scheme 6). However, methylation
of the thiourea 6a did not provide the desired N-
methylthiourea 6y but the S-methylated isothiourea.
Therefore, we prepared 6y via thiocarbamoyl chloride
from N-methylbenzylamine and thiophosgene under the
same conditions of method I as shown in Scheme 7.
The methylated piperazine analogues were obtained
as shown in Scheme 8. Condensation of 1325 with (RS)-
2-methylpiperazine, C2-symmetric (RS)-trans-2,5-di-
methylpiperazine or cis-2,6-dimethylpiperazine follow-
ing treatment with iso(thio)cyanate gave as sole prod-
ucts 17-19, respectively. The homopiperazine analogue
21 was obtained from 2025 as shown in Scheme 9.
Next, we attempted to replace the phenyl ring with
other ring systems, especially with heterocycles in
expectation of improvement for the aqueous solubility,
and to obtain some SARs as shown in Table 3. Regard-
ing the urea analogues, pyridyl analogues (4l, 4m , and
4o) were devoid of any activity. Introduction of chlorine
atom on 3-pyridine ring at 5-position (i.e., para substi-
tution, 4n ) somewhat enhanced activity but the IC50
value was still weak. Thienyl analogues (4p and 4q)
showed similar activity with initial KN1022, and inser-
tion of one methylene unit (4r ) was detrimental. In
marked contrast of ureas, several pyridine-containing
thiourea analogues showed moderate activity. Among
pyridylthioureas (6o, 6p , 6r ), 4-pyridyl (6r ) and 3-py-
ridyl (6p ) analogues showed similar activity with
Resu lts a n d Discu ssion s
SAR for In h ibition of â-P DGF R P h osp h or yla -
tion . As further exploration for the SAR of KN1022
derivatives, we prepared a series of analogues examin-
ing the effect of the linker between phenyl ring and the
(thio)urea moieties, replacement and substitutions of
these moieties, and the piperazine moiety on inhibitory
activity against the â-PDGFR. We also attempted to
improve aqueous solubility by replacing the phenyl ring
with heterocyclic rings such as pyridine. All the ana-
logues prepared were evaluated for their inhibition of
â-PDGFR phosphorylation in accordance with a previ-
ously reported whole cell assay,30 and the resulting IC50
values are listed in Tables 2-4.

4516 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20
Matsuno et al.
Sch em e 5a
a
(a) (PhO)2NCN, iPrOH, reflux, for 7a , 46%; (b) (MeS)2NCN, EtOH, reflux, for 7b, 84%; (c) (MeS)2CdC(CN)2, MeCN, reflux, for 8, 85%;
(d) (MeS)2CdCHNO2, EtOH, reflux, for 9, 31%; (e) R-NH2, solvent, heat.
Sch em e 6
that the hydrogen atom is essential for the activity.
Since KN734 was found to be competitive with ATP
using purified receptor kinase domain expressed in
insect cells,30 we speculated that the acidic hydrogen
on the (thio)urea moiety interacts at a site of PDGFR
similar to the phosphate moiety of ATP.
Finally, modification of the piperazine ring had no
positive influence on the activity (Table 5). Introduction
of methyl group on the piperazine ring, 2-methyl (17),
and cis-2,6-dimethyl (18) analogues retained activity
compared with the parent compounds (1f, 6a ); however,
the trans-2,5-dimethyl analogue 19 showed very poor
activity, so introduction of methyl group at 5-position
of piperazine ring was detrimental effect on the activity.
Furthermore, exchanging with the homopiperazine (21)
reduced activity. These results suggest that the orienta-
tion of quinazoline ring and carbamoyl moiety are
important for interaction with PDGFR and/or steric
tolerance of piperazine-interacting site is quite limited.
Sch em e 7
Kin a se Selectivity. We also evaluated three potent
compounds KN734, 6a , and 4u (hydrochloride of 4q) for
inhibitory activity on various kinases, including c-kit
and Flt3, which are closely related PDGFR-family
tyrosine kinases31 using previously reported meth-
ods.30,32 As shown in Table 6, all compounds showed
similar inhibitory activity for PDGFRs and c-kit. For
Flt3, better selectivity with 10 to more than 100-fold
was observed. KN734 showed weak inhibitory activity
against vascular endothelial growth factor-2 (VEGF-2);
however, no significant inhibition was observed on other
receptor tyrosine kinases (epidermal growth factor
receptor; EGFR, fibroblast growth factor; FGFR, VEGF-
2), nonreceptor tyrosine kinases (src, abl), and Ser/Thr
kinases (protein kinase A; PKA, protein kinase C; PKC)
at 100-1000 higher concentrations. These studies also
demonstrate that our synthesized compounds retained
good selectivity for the PDGFR-family tyrosine kinases,
similar to that in our previous report.24
KN1022; however, 2-pyridyl analogue 6o was inactive.
Substitution on 3-pyridine ring at 5-position (6q) had a
negligible effect on potency. Insertion of a methylene
(6s) was acceptable; however, extension of the methyl-
ene chain to ethylene (6t) abolished the activity. Fur-
thermore, 6v and 6w , which are perhydrogenated
analogues of the furfuryl analogue 6u and benzyl
analogue 6a , respectively, showed no activity. These
results indicate that the aromaticity in this moiety is
essential for the inhibitory activity.
To further optimize the (thio)urea moiety, we pre-
pared several related compounds as listed Table 4. In
particular, the high potency shown by the several
benzylthiourea analogues prompted us to evaluate the
cyanoguanidine 10, which is a well-known bioisotere of
the thiourea, and the related derivatives (11 and 12).
Cyanoguanidine analogues showed inhibitory activity
with almost the same preference of substituents as the
thiourea analogues for orientation (comparison 10a ,
10b, and 10c) and group (comparison 10d and 10e) on
the phenyl ring, albeit less potent than the thiourea
analogues (comparison 10a and 6b). Among the cyan-
oguanidine analogues, 10f (IC50 ) 0.19 µmol/L) showed
the most potent activity. Additionally, replacement of
(thio)urea by dicyanovinyl 11, nitrovinyl 12, acylthio-
urea 6x, or sulfonylurea 4s was not tolerated; therefore,
benzylthioureas was optimal for their potent activity in
this region. Replacement of NH moiety by oxygen (3b)
and N-methylation of (thio)urea moiety (4t and 6y)
completely abolished activity. These results indicated
Aqu eou s Solu bilit y. We obtained many potent
inhibitors of PDGFR phosphorylation, and these were
expected to possess therapeutic potential; however,
aqueous solubility of the parent compound KN1022 was
not satisfactory for oral administration (Table 7). We
evaluated the solubility in phosphate buffer (pH 7.4) and
log D values of some potent analogues (4q, 6s, and 6u )
which were expected to improve the solubility by
replacement of the phenyl ring with a heterocyclic ring.
As listed in Table 7, the log D values and the aqueous
solubility of these compounds were improved over that
of KN1022. Especially, 3-thienyl analogue 4q and 3-py-

Inhibitors of PDGF Receptor Phosphorylation
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20 4517
Sch em e 8a
a
i
(a) methylated-piperazine (excess), PrOH, reflux; (b) R-NCX, solvent.
Ta ble 3. Synthetic Method and Inhibitory Activity on
â-PDGFR Phosphorylation
Sch em e 9
a,b
IC50
Ta ble 2. Synthetic Method and Inhibitory Activity on
â-PDGFR Phosphorylationa
no.
R
Y
X
procedure
(µmol/L)
4l
2-pyridyl
3-pyridyl
3-(5-Cl)pyridyl
4-pyridyl
2-thienyl
3-thienyl
3-thienyl
2-pyridyl
3-pyridyl
3-(5-Cl)pyridyl
4-pyridyl
3-pyridyl
3-pyridyl
furfuryl
none
none
none
none
none
none
CH2
none
none
none
none
CH2
O
O
O
O
O
O
O
S
S
S
S
S
method B
method C
method C
method C
Scheme 3
method D
method D
method I
method H
method I
method I
method H
method I
method H
method H
>10
>30
8.23
14.1
0.41
0.56
>30
>30
0.41
0.55
0.98
0.28
20.1
0.33
>30
4m
4n
4o
4p
4q
4r
6o
6p
6q
6r
6sc
6t
CH2CH2
CH2
S
S
S
a,b
IC50
procedure (µmol/L)
6u
6v
no.
4a
4b
4c
4d
4e
4f
R
Y
X
(RS)-tetrahydro- CH2
furfuryl
cyclohexyl
4-Cl
4-F
4-Br
4-Me
4-Pr
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
O
O
O
O
O
O
O
O
O
O
O
S
S
S
S
S
S
S
S
S
method G
method E
method G
method F
method G
method F
method E
method B
method F
method G
method F
method H
method H
method H
method H
method J
method H
method I
method I
method H
method I
method H
method H
method H
1.27
9.59
0.74
2.94
0.55
0.11
3.06
0.38
1.87
5.84
0.14
0.55
0.07
0.23
0.98
0.03
0.03
0.20
0.16
0.10
0.96
2.41
0.09
0.54
6w
CH2
S
method H
>10
a
b
IC50(µmol/mL) of â-PDGFR phosphorylation. Autophospho-
rylation was measured in intact cells using a two-site ELISA.30
c 2HCl salt.
4-tert-Bu
4-MeO
4-PhO
4g
4h
4i
P la sm a Dr u g Con cen tr a tion a fter Or a l Ad m in -
istr a tion to Ra ts. To select some oral available ana-
logues which also afford high plasma drug concentration
over time for in vivo evaluation, we measured plasma
concentration of several KN1022 analogues at 1 and 8
h after oral administration (30 mg/kg) to Sprague-
Dawley rats (SD rats, n ) 2) as shown in Table 8. We
observed same relationships between the structure and
plasma concentration like in our previous report,24 i.e.,
the plasma concentration of the urea 4g was found to
be higher than that of the corresponding thiourea 6i.
The plasma concentration of KN734 was maintained at
2-4 µg/mL up to 8 h. Additionally, the plasma concen-
trations of 6b and 4q in each rats were different. The
results indicated that there might be metabolic poly-
morphism of these analogues in SD rats.
We also evaluated Tmax, Cmax, T1/2, and AUC0-∞ for
several analogues as listed in Table 9. Compounds 4q,
KN734, and 6u showed longer T1/2 and higher AUC0-∞
than 6s, as easily predicted form the data in Table 8.
In h ibitor y Effect on Neoin tim a F or m a tion a fter
Ba lloon In ju r y of Ra t Ca r otid Ar ter y a n d oth er
Biologica l Effects. We evaluated the effect on neoin-
3,4-(OCH2O)- CH2
4j
4-Cl
4-Br
H
4-Cl
3-Cl
2-Cl
4-Br
CH2CH2
CH2CO
CH2
4k
6a
6b
6c
6d
6e
6f
6g
6h
6i
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
4-Me
4-iPr
4-tert-Bu
4-MeO
4-PhO
3,4-(MeO)2
6j
6k
CH2
CH2
S
S
S
S
S
S
KN734 3,4-(OCH2O)- CH2
(S)-6l
(R)-6l
6m
H
H
4-Cl
(S)-(Me)CH
(R)-(Me)CH
CH2CH2
method H >30
method H
method J
1.09
>30
6n
a
b
IC50 (µmol/mL) of â-PDGFR phosphorylation. Autophospho-
rylation was measured in intact cells using a two-site ELISA.30
ridylmethyl analogue dihydrochloride 6s showed 50-fold
higher aqueous solubility than initial parent compound
KN1022.

4518 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20
Matsuno et al.
Ta ble 4. Synthetic Method and Inhibitory Activity on
â-PDGFR Phosphorylation
Ta ble 6. Kinase Specificitya
IC50 (µmol/L)
kinase
6a
0.55
0.24
>100
>200
>30
>100
>30
NT
KN734
4u b
â-PDGFR
R-PDGFR
EGFR
FGFR
CSF-1R
VEGFR-2
Src
Abl
PKA
PKC
Mek 1
Mkk 3
Mkk 6
Erk
J nk
p38
0.14
0.21
>100
160
>30
17.3
>30
>30
>30
>30
>30
NT
>30
>30
>30
>30
0.22
14.9
0.56
NT
>100
>30
NT
NT
NT
NT
>30
>30
NT
NT
NT
NT
NT
NT
0.8
a
b
IC50
,
no.
R
Y
X
procedure (µmol/L)
>30
>30
>30
>30
>30
>30
>30
>30
10a 4-ClPh
10b 3-ClPh
10c 2-ClPh
NHCH2 NCN
NHCH2 NCN
NHCH2 NCN
NHCH2 NCN
NHCH2 NCN
Scheme 5
Scheme 5
Scheme 5 >30
Scheme 5
Scheme 5
Scheme 5
Scheme 5
0.96
23.5
10d 4-MePh
0.34
10e 4-iPrPh
1.38
0.19
5.24
10f 3,4-(OCH2O)-Ph NHCH2 NCN
11 4-ClPh NHCH2 C(CN)2
c-kit
Flt3
0.36
>30
12 3,4-(OCH2O)-Ph NHCH2 CH(NO2) Scheme 5 >30
7.02
6x 4-ClPh
4s 4-ClPh
3b 4-NO2Ph
4t 4-BrPh
NHCO
NHSO2
O
NMe
NMeCH2
S
method H >30
method A >30
Scheme 1 >30
Scheme 6 >30
Scheme 7 >30
O
O
O
S
a
Autophosphorylation of all receptor tyrosine kinases were
measured in intact cells using a two-site ELISA.30 For all other
kinases, substrate phosphorylation was measured in an in vitro
6y Ph
assay with purified enzyme.30 HCl salt of 4q. NT: not tested.
b
a
b
IC50 (µmol/mL) of â-PDGFR phosphorylation. Autophospho-
30
Ta ble 7. Solubility in Aqueous Phosphate Buffer (pH 7.4)a
rylation was measured in intact cells using a two-site ELISA.
no.
solubility (µg/mL)
log D
Ta ble 5. Inhibitory Activity on â-PDGFR Phosphorylation
KN1022
4q
0.049
2.0
2.2
3.22
2.72
2.49
2.75
6sb
6u
0.96
a
Solubility in aqueous phosphate buffer (pH 7.4) at 20 °C,
b
determined by HPLC. 2HCl salt.
Ta ble 8. Plasma Concentration after Oral Administration to
Rats (30mg/kg, n ) 2)
plasma concentration
(µg/mL)
no.
4g
1 h
7.3
11.6
5.4
8.1
2.4
<0.1
2.3
2.5
5.1
5.9
12.4
7.7
2.6
2.6
8h
1.4
1.9
1.6
0.9
1.3
<0.1
0.4
0.5
2.4
3.6
3.7
0.7
<0.1
<0.1
1.2
a,b
IC50
rat 1
rat 2
rat 3
rat 4
rat 5
rat 6
rat 7
rat 8
no.
R
X
(µmol/L)
17
18
19
21
4-PhOPh
Bn
4-PhOPh
4-PhOPh
O
S
O
O
0.08
0.64
6a
>30
6b
0.65
6i
a
b
IC50 (µmol/mL) of â-PDGFR phosphorylation. Autophosphor-
ylation was measured in intact cells using a two-site ELISA.
30
KN734
4q
rat 9
rat 10
rat 11
rat 12
rat 13
rat 14
rat 15
rat 16
tima formation after balloon injury of rat carotid artery
by 4q, KN734, and 6u , which showed good oral absorp-
tion and high plasma drug concentration at 8 h.
Compounds were suspended in methylcellulose 400 and
were orally administrated (30 mg/kg) to SD rats twice
daily for a period of 15 days starting on the day before
the balloon injury. As shown in Table 10, all compounds
showed significant inhibition of neointima formation
relative to vehicle treated controls (p < 0.05, Student’s
t-test or Aspin-Welch test). The reduction of I/M ratios
for 4q, KN734, and 6u was 31%, 31%, and 45%,
respectively. No obvious affect on rat body weight was
observed (data not shown). Based on these data, 4-[4-
(N-substituted (thio)carbamoyl)-1-piperazinyl]-6,7-di-
methoxyquinazoline derivatives, which are inhibitors of
PDGFR phosphorylation, may be expected to represent
a new approach for treating various aspects of athero-
sclerosis. Additionally, the simple and conventional
measurement of plasma drug concentration as described
6s
6u
3.0
3.7
1.4
Ta ble 9. PK Parameters after Oral Administration to Rats (30
mg/kg, n ) 3)
Tmax
(h)
Cmax
(µg/mL)
T1/2
(h)
AUC0-∞
no.
4q
KN734
6s
(µg h mL-1
)
3.33
3.33
0.67
3.67
15.9
14.5
6.98
7.20
4.25
3.92
2.11
3.33
145
89.9
9.84
95.8
6u
in Table 8 was useful method to select the suitable
compounds for evaluating in this model.
We have recently reported that KN734 (CT52923) was
a potent inhibitor of the smooth muscle cell proliferation
and migration induced by PDGF-BB.30 KN734 also

Inhibitors of PDGF Receptor Phosphorylation
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20 4519
Ta ble 10. Inhibitory Activity on Neointima Formation in Rat
Ack n ow led gm en t. The technical assistance of Ms.
Kumi Aoki, Miyuki Akimoto, and Chika Okitsu is
acknowledged. We acknowledge Mrs. Naomi Kobayashi
for her information retrieval. We also acknowledge Mr.
Masayuki Abe and Dr. Yoichi Uozaki for their support
of structure determination and Dr. Robert M. Scarbor-
ough and Dr. Anjali Pandey for their encouragement
in preparing this article. The authors gratefully ap-
preciate Mrs. Yumiko Aono for her great technical
assistance in chemical synthesis.
Cartoid Arterya
no. of animals
I/M ratio
cmpd
no.
4q
KN734
6u
vehicle treated
vehicle
cmpd treated
10
9
10
10
9
0.99 ( 0.07 0.69 ( 0.06 (p < 0.05)
0.95 ( 0.07 0.61 ( 0.07 (p < 0.05)
0.86 ( 0.10 0.47 ( 0.04 (p < 0.05)
9
a
All results were mean ( S.E.M.
Exp er im en ta l Section
showed several in vivo effects by oral administration,
i.e., suppression of neointima formation following bal-
loon injury in rat carotid artery with various doses,30
reduction of tumor growth of NIH/3T3 cells transformed
by PDGF in nude mouse,33 and improvement of survival
due to a delay in disease progression of mouse model of
chronic myelomonocytic leukemia.34 Therefore, 4-[4-(N-
substituted (thio)carbamoyl)-1-piperazinyl]-6,7-dimeth-
oxyquinazoline derivatives have a therapeutic potential
especially for treating various aspects of atherosclerosis,
cancer and leukemia. Glivec (Gleevec), which is a
phenylaminopyrimidine inhibitor of bcr/abl kinase and
recently launched for indication for chronic myelogenous
leukemia, also has the inhibitory activity against c-kit.
As recent studies have shown that c-kit plays a central
role in the pathogenesis of gastrointestinal stromal
tumor (GIST)35,36 and this agent was demonstrated to
have the therapeutic benefit for metastatic GIST,37 our
analogues may also possess therapeutic potential for
GIST.
Melting points were determined on BU¨ CHI 535 Melting
Point or Yanaco Model MP (Micro Melting Point Apparatus)
on compounds isolated as described in the experimental
procedures and are uncorrected. Analytical TLC was carried
out on E. Merck 0.25 mm silica gel precoated glass plates (60
F-254) with detection by UV light. Normal phase silica gel (EM
Science, Silica Gel 60) was used for chromatography. 1H NMR
spectra were recorded on J EOL J NM-EX270 (270 MHz) FT
NMR Spectrometer, J EOL J NM-GX270 (270 MHz) FT NMR
Spectrometer or Varian Unity + 400 spectrometer. Chemical
shifts are reported as δ values (parts per million) downfield
from internal TMS in appropriate organic solutions. FAB-mass
spectra were recorded with J EOL J MS-DX303 Mass Spec-
trometer. Low-resolution EI-mass spectra were recorded with
J EOL GC-Mate Mass Spectrometer. TOF-mass spectra were
recorded with Micromass Quattro Mass Spectrometer. The IR
spectra were recorded with J ASCO IR-810 IR spectrometer
or HORIBA FT-200 IR spectrometer. Combustion analysis
(CHN) were performed by Perkin-Elmer Series II CHNS/O
Analyzer 2400 and agreed with theoretical values to within
(0.4%. Supporting Information is available.
The typical synthetic methods were described as followed
except previous reported method A, B, H, and I.24
Meth od C. A solution of nicotinoyl chloride hydrochloride
(5.9 g, 33 mmol) in Et2O (50 mL) was added dropwise with
vigorously stirring to an aqueous solution (50 mL) of sodium
azide (12.0 g, 185 mmol) at 0 °C. The organic layer was
separated, washed with brine, dried over MgSO4, and carefully
evaporated under 30 °C. The residue was dissolved in toluene
(40 mL). After 2 (548 mg, 2.00 mmol) was added, the mixture
was heated at 70 °C for 3 h. The residue after the removal of
solvent was purified by silica gel column chromatography and
recrystallized from EtOAc to provide 4m (197 mg, 0.50 mmol).
Meth od D. After a mixture of 3-thiophenecarboxylic acid
(5.46 g, 42.7 mmol), triethylamine (6.25 mL, 44.8 mmol), and
diphenylphosphoryl azide (9.67 mL, 44.9 mmol) in toluene (200
mL) solution was heated at 70 °C for 4 h, 2 (6.16 g, 22.5 mmol)
was added. The reaction mixture was heated at 80 °C for 3 h,
cooled, poured into water, extracted with CHCl3, washed with
brine, and dried over MgSO4. The residue after the removal
of solvent was purified by silica gel column chromatography
eluting with EtOAc/MeOH (100:5 to 100:8) and recrystallized
from EtOAc to provide 4q (11.0 g, 27.6 mmol).
Meth od E. To a solution of 4-methoxyphenyl 4-nitrophenyl
carbonate (954 mg, 3.30 mmol) in acetonitrile (20 mL) was
added solution of 4-fluorobenzylamine (375 mg, 3.00 mmol)
in acetonitrile (5 mL). After the reaction mixture was stirred
for 1 h at room temperature, 2 (548 mg, 2.00 mmol) and DBU
(0.33 mL, 2.20 mmol) were added, and then resulting mixture
was refluxed for 1.5 h. The residue after the removal of solvent
was purified by silica gel column chromatography eluting with
EtOAc/CHCl3/MeOH (50:10:2 to 50:10:4) and recrystallization
from EtOAc to provide 4b (480 mg, 1.13 mmol).
Con clu sion s
SARs in the (thio)urea moiety, the phenyl ring itself,
the linker between these two moieties, and the pipera-
zine moiety were investigated in the 4-(1-piperazinyl)-
quinazoline series of PDGFR phosphorylation inhibitors.
The effect of the linker was quite different, i.e., for ureas
with decreasing activity and for thioureas with increas-
ing activity. Regarding the (thio)urea moiety, cyan-
oguanidine, which is well-known as bioisostere of thio-
urea, and related nitrovinyl or dicyanovinyl group were
not suitable for potent activity. A hydrogen atom on the
(thio)urea moiety was essential for the activity. We also
demonstrated that a stereochemistry possess major
consequences for inhibition of PDGFR phosphorylation.
Through these modifications, benzylthioureas with a
relatively small substituent on the 4-position (6b, 6e,
6f, etc.) and 3,4-methylenedioxy group (KN734) were
found to be optimal for selective and potent activity.
Replacement of the phenyl ring by heterocycles (4q, 6s)
improves the aqueous solubility without activity and
loss of selectivity. Introduction of methyl group on
5-position of the piperazine ring and replacement by
homopiparazine reduced the activity.
Since KN734 inhibited smooth muscle cell prolifera-
tion and migration induced by PDGF-BB and 4q,
KN734, and 6u suppressed neointima formation follow-
ing balloon injury in rat carotid artery by oral admin-
istration, 4-[4-(N-substituted (thio)carbamoyl)-1-piper-
azinyl]-6,7-dimethoxyquinazoline derivatives may be
expected to represent a therapeutic potential for rest-
enosis.
Meth od F . A mixture of 3a (389 mg, 1.16 mmol), 4-tert-
butylbenzylamine (0.64 mL, 3.45 mmol), and triethylamine
(0.81 mL, 5.81 mmol) in DMF (10 mL) solution was stirred
overnight at room temperature under argon atmosphere. The
reaction mixture was poured into water, and then NaCl was
added. The resulting precipitate was collected, washed with
water, dried, and purified by silica gel column chromatography

4520 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20
Matsuno et al.
eluting with EtOAc/CHCl3/MeOH 50:10:4 to provide 4f (515
mg, 1.11 mmol).
210 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C26H33N5O3
0.25EtOAc) C, H, N.
Meth od G. A mixture of 3b (815 mg, 1.86 mmol) and
4-chlorobenzylamine (1.13 mL, 9.29 mmol) in NMP (20 mL)
solution was heated at 60 °C for 4.5 h. The reaction mixture
was cooled, poured into brine, extracted with CHCl3, and dried
over Na2SO4. The residue after the removal of solvent was
purified by silica gel column chromatography eluting with
EtOAc/CHCl3/MeOH 50:10:5 to provide 4a (621 mg, 1.40
mmol).
4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(4-m eth oxyben zyl)-
1-p ip er a zin eca r boxa m id e (4 g). 34% by method E; mp 147-
148 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C23H27N5O4
0.25H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(4-ph en oxyben zyl)-
1-p ip er a zin eca r boxa m id e (4h ). 82% by method B; mp 170-
1
171 °C (EtOAc), H NMR, FABMS, IR, Anal. (C28H29N5O4) C,
H, N.
Meth od J . A mixture of 5 (502 mg, 1.42 mmol), 4-bro-
mobenzylamine hydrochloride (950 mg, 4.27 mmol), and tri-
ethylamine (1.00 mL, 7.17 mmol) in DMF (10 mL) solution
was stirred overnight at room temperature under argon
atmosphere. The reaction mixture was poured into water; then
NaCl was added. The resulting precipitate was collected,
washed with water, dried, and purified by silica gel column
chromatography eluting with EtOAc/CHCl3 50:10 to provide
6e (543 mg, 1.08 mmol).
4-(6,7-Dim et h oxy-4-q u in a zolin yl)-1-p ip er a zin eca r b o-
n yl Ch lor id e (3a ). To a 0 °C solution of triphosgene (5.41 g,
18.2 mmol) in dichloromethane (50 mL) was added slowly a
dichloromethane (20 mL) solution of 2 (5.00 g, 18.2 mmol)
under argon atmosphere. After triethylamine (7.62 mL, 54.7
mmol) was added slowly, the reaction mixture was stirred for
2 h under the same temperature. The residue after the removal
of solvent was purified by silica gel column chromatography
eluting with EtOAc/acetone 7:1 to provide 4-(6,7-dimethoxy-
4-quinazolinyl)-1-piperazinecarbonyl chloride (3a ) (2.30 g, 6.84
mmol) in 38% yield.
4-(6,7-Dim et h oxy-4-q u in a zolin yl)-N-(3,4-m et h ylen e-
dioxyben zyl)-1-piper azin ecar boxam ide (4i). 75% by method
F; mp 172-173 °C (EtOAc), 1H NMR, FABMS, IR, Anal.
(C23H25N5O5 0.25H2O) C, H, N.
N-[2-(4-Ch lor op h en yl)et h yl]-4-(6,7-d im et h oxy-4-q u i-
n a zolin yl)-1-p ip er a zin eca r boxa m id e (4j). 70% by meth-
od G; mp 177-178 °C (EtOAc), 1H NMR, FABMS, IR,
(C23H26ClN5O3) C, H, N.
N-(4-Br om oph en acyl)-4-(6,7-dim eth oxy-4-qu in azolin yl)-
1-p ip er a zin eca r boxa m id e (4k ). 72% by method F; mp 198-
1
199 °C (EtOAc) H NMR, FABMS, IR, Anal. (C23H24BrN5O4)
C, H, N.
N-Ben zyl-4-(6,7-d im et h oxy-4-q u in a zolin yl)-1-p ip er a -
zin eth ioca r boxa m id e (6a ). 61% by method H; mp 187-189
1
°C (CHCl3-iPr2O), H NMR, FABMS, IR, Anal. (C22H25N5O2S
0.5H2O) C, H, N.
N-(4-Ch lor oben zyl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin eth ioca r boxa m id e (6b). 77% by method H; mp
218-220 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal.
(C22H24ClN5O2S) C, H, N.
N-(3-Ch lor oben zyl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin eth ioca r boxa m id e (6c). 98% by method H; mp
117-119 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal.
(C22H24ClN5O2S H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-1-p ip er a zin eca r box-
ylic Acid 4-Nitr op h en yl Ester (3b). To a 0 °C solution of 2
(1.00 g, 3.65 mmol) in CHCl3 (25 mL) solution were added
triethylamine (2.54 mL, 18.2 mmol) and 4-nitrophenyl chlo-
roformate (0.88 g, 4.36 mmol). The reaction mixture was
stirred overnight at room temperature, poured into water,
extracted with CHCl3, and dried over MgSO4. The residue after
the removal of solvent was purified by silica gel column
chromatography eluting with EtOAc/acetone 7:1 to provide 3b
N-(2-Ch lor oben zyl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin eth ioca r boxa m id e (6d ). 89% by method H; mp
1
175-176 °C (CHCl3-iPr2O), H NMR, FABMS, HRMS-FAB,
IR, Anal. (C22H24ClN5O2S 0.5H2O 0.25iPr2O) C, H, N.
1
(1.16 g, 2.73 mmol) in 75% yield; mp 230-231 °C (CHCl3), H
N-(4-Br om oben zyl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin eth ioca r boxa m id e (6e). 76% by method J ; mp
NMR, EIMS, IR, Anal. (C21H21N5O6 0.25H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-1-p ip er a zin eth ioca r -
bon yl Ch lor id e (5). To a 0 °C solution of thiophosgene (3.06
mL, 40.1 mmol) in dichloromethane (100 mL) was added slowly
a dichloromethane (100 mL) solution of 2 (10.0 g, 36.5 mmol)
under argon atmosphere. After triethylamine (12.4 mL, 89.1
mmol) was added slowly, the reaction mixture was stirred for
2 h under the same temperature. The residue after the removal
of solvent was purified by silica gel column chromatography
eluting with EtOAc/acetone (7:1 to 5:1) to provide 4-(6,7-
dimethoxy-4-quinazolinyl)-1-piperazinethiocarbonyl chloride
(5) (6.65 g, 18.9 mmol) in 52% yield.
217-218 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C22H24
BrN5O2S 0.25EtOAc) C, H, N.
-
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(4-m eth ylben zyl)-
1-p ip er a zin eth ioca r boxa m id e (6f). 89% by method H; mp
202-204 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal.
(C23H27N5O2S) C, H, N.
4-(6,7-Dim et h oxy-4-q u in a zolin yl)-N-(4-isop r op ylb en -
zyl)-1-p ip er a zin eth ioca r boxa m id e (6 g). 86% by method
I; mp 178-179 °C (EtOAc), 1H NMR, FABMS, IR, Anal.
(C25H31N5O2S) C, H, N.
N-(4-ter t-Bu tylben zyl)-4-(6,7-dim eth oxy-4-qu in azolin yl)-
1-p ip er a zin eth ioca r boxa m id e (6h ). 91% by method I; mp
104-105 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal.
(C26H33N5O2S 0.25H2O 0.25iPr2O) C, H, N.
N-(4-Ch lor oben zyl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin eca r boxa m id e (4a ). 76% by method G; mp 203-
204 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal. (C22H24
ClN5O3 0.5H2O) C, H, N.
-
4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(4-m eth oxyben zyl)-
1-p ip er a zin eth ioca r boxa m id e (6i). 72% by method H; mp
4-(6,7-Dim et h oxy-4-q u in a zolin yl)-N-(4-flu or ob en zyl)-
1-p ip er a zin eca r boxa m id e (4b). 53% by method E; mp 200-
201 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C22H24FN5O3)
C, H, N.
1
201-204 °C (CHCl3-iPr2O), H NMR, FABMS, HRMS-FAB,
IR, Anal. (C23H27N5O3S 0.5H2O 0.25iPr2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(4-ph en oxyben zyl)-
1-p ip er a zin eth ioca r boxa m id e (6j). 89% by method I; mp
218-219 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C28H29N5O3S
H2O) C, H, N.
N-(4-Br om oben zyl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin eca r boxa m id e (4c). 55% by method G; mp 211-
212 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal. (C22H24
-
BrN5O3 0.25H2O) C, H, N.
N-(3,4-Dim eth oxyben zyl)-4-(6,7-dim eth oxy-4-qu in azoli-
n yl)-1-p ip er a zin eth ioca r boxa m id e (6k ). 82% by method H;
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(4-m eth ylben zyl)-
1-p ip er a zin eca r boxa m id e (4d ). 58% by method F; mp 174-
1
mp 196-197 °C (CHCl3-iPr2O), H NMR, FABMS, IR, Anal.
1
175 °C (EtOAc), H NMR, FABMS, IR, Anal. (C23H27N5O3) C,
(C24H29N5O4S 0.25H2O) C, H, N.
H, N.
4-(6,7-Dim et h oxy-4-q u in a zolin yl)-N-(3,4-m et h ylen e-
dioxyben zyl)-1-piper azin eth iocar boxam ide (KN734). 86%
by method H; mp 113-114 °C (EtOAc), 1H NMR, FABMS, IR,
Anal. (C23H25N5O4S 0.25H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(4-isopr opylben zyl)-
1-p ip er a zin eca r b oxa m id e (4e). 31% by method G; mp
135-136 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal.
(C25H31N5O3) C, H, N.
N-(4-ter t-Bu tylben zyl)-4-(6,7-dim eth oxy-4-qu in azolin yl)-
1-p ip er a zin eca r boxa m id e (4f). 96% by method F; mp 209-
(R)-4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(1-ph en yleth yl)-
1-p ip er a zin eth ioca r boxa m id e ((R)-6l). 82% by method H,

Inhibitors of PDGF Receptor Phosphorylation
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20 4521
mp 99-101 °C (CHCl3-MeOH-iPr2O), 1H NMR, FABMS, IR,
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(2-p yr id yl)-1-p ip -
er a zin eth ioca r boxa m id e (6o). 30% by method I; mp 208-
210 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H22N6O2S
0.25EtOAc) C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(3-p yr id yl)-1-p ip -
er a zin eth ioca r boxa m id e (6p ). 100% by method H; mp 169-
171 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H22N6O2S
0.25H2O) C, H, N.
25
Anal. (C23H27N5O2S 0.5H2O) C, H, N. [R]D + 6.09° (c 0.49,
CHCl3).
(S)-4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(1-ph en yleth yl)-
1-p ip er a zin eth ioca r boxa m id e ((S)-6l). 88% by method H;
mp 98-100 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal.
(C23H27N5O2S 1.5H2O) C, H, N. [R]D25-6.66° (c 0.53, CHCl3).
N -[2-(4-C h lo r o p h e n y l)e t h y l]-4-(6,7-d im e t h o x y -4-
qu in a zolin yl)-1-p ip er a zin eth ioca r boxa m id e (6m ). 74% by
method H; mp 106-109 °C (CHCl3-iPr2O), 1H NMR, FABMS,
IR, Anal. (C23H26ClN5O2S 0.5H2O) C, H, N.
N -[1-(4-C h lo r o p h e n y l)c y c lo p r o p y lm e t h y l]-4-(6,7-
d im et h oxy-4-q u in a zolin yl)-1-p ip er a zin et h ioca r b oxa m -
id e (6n ). 91% by method J ; mp 108-111 °C (EtOAc), 1H NMR,
FABMS, IR, Anal. (C25H28ClN5O2S H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(2-p yr id yl)-1-p ip -
er a zin eca r boxa m id e (4l). 44% by method B; mp 101-102
°C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H22N6O3 1.25H2O)
C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(3-p yr id yl)-1-p ip -
er a zin eca r boxa m id e (4m ). 25% by method C; mp 208-209
°C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H22N6O3 0.25H2O)
C, H, N.
N-(6-Ch lor o-3-pyr idyl)-4-(6,7-dim eth oxy-4-qu in azolin yl)-
1-p ip er a zin eth ioca r boxa m id e (6q). 73% by method I; mp
154-156 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H21
ClN6O2S H2O 0.25EtOAc) C, H, N.
-
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(4-p yr id yl)-1-p ip -
er a zin eth ioca r boxa m id e (6r ). 43% by method I; mp 218-
220 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H22N6O2S
H2O) C, H, N.
4-(6,7-Dim et h oxy-4-q u in a zolin yl)-N-(3-p icolyl)-1-p ip -
er a zin eth ioca r boxa m id e d ih yd r och lor id e (6s). To a 0 °C
suspension of free base of 6s (437 mg, 1.03 mmol) obtained by
method H in EtOAc (50 mL) was added 4 mol/L hydrogen
chloride in EtOAc solution (2.58 mL, 10.3 mmol). After the
mixture was stirred for 15 min at room temperature, the
resulting precipitate was collected, washed with EtOAc, and
dried to provide hydrochloride 6s (428 mg, 0.86 mmol) in 83%
yield; mp 183-192 °C (EtOAc), 1H NMR, FABMS, IR, Anal.
(C21H24N6O2S 2HCl H2O) C, H, N.
N-(6-Ch lor o-3-pyr idyl)-4-(6,7-dim eth oxy-4-qu in azolin yl)-
1-p ip er a zin eca r boxa m id e (4n ). 53% by method C; mp 238-
240 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H21ClN6O3
0.5H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(4-p yr id yl)-1-p ip -
er a zin eca r boxa m id e (4o). 76% by method C; mp 141-143
°C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H22N6O3 0.75H2O)
C, H, N.
4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-[2-(3-pyr idyl)eth yl]-
1-p ip er a zin eth ioca r boxa m id e (6t). 97% by method H; mp
124-125 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C22H26N6O2S
0.75H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-fu r fu r yl-1-p ip er a -
zin eth ioca r boxa m id e (6u ). 99% by method H; mp 189-190
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(2-th ien yl)-1-p ip -
er azin ecar boxam ide (4p). (1) To a 0 °C solution of 2-thiophen-
ecarboxylic acid (1.00 g, 7.80 mmol) in 1,4-dioxane (20 mL)
were added triethylamine (1.63 mL, 11.7 mmol) and DPPA
(1.68 mL, 7.80 mmol). The mixture was stirred for 3 h at room
temperature, followed by addition of tert-butyl alcohol (1.12
mL, 11.7 mmol), and heated at 80 °C for 4.5 h. After further
addition of tert-butyl alcohol (1.12 mL, 11.7 mL), heating at
80 °C for 1.5 h, and the removal of solvent, the residue was
purified by silica gel column chromatography to provide 2-tert-
butoxycarbonylaminothiophene29 (1.05 g, 5.28 mmol) in 68%
yield; EIMS (m/z): 199 (M)+. (2) To a solution of 2-tert-
butoxycarbonylaminothiophene (500 mg, 2.51 mmol) in Et2O
(20 mL) was added hydrochloric acid (9 mL). The mixture was
stirred for 30 min at room temperature, evaporated under 30
°C, and azeotroped with 1,4-dioxane. The residue was sus-
pended in dichloromethane (15 mL). CDI (479 mg, 2.19 mmol),
followed by triethylamine (0.76 mL, 5.45 mmol), was added
at 0 °C, and the reaction mixture was stirred at the same
temperature for 1 h. After 2 (500 mg, 1.82 mmol) was added,
the resulting mixture was stirred at room-temperature over-
night. The residue after the removal of solvent was purified
by silica gel column chromatography to provide 4p (479 mg,
1
°C (CHCl3-iPr2O), H NMR, FABMS, IR, Anal. (C20H23N5O3S
0.25H2O) C, H, N.
(RS)-4-(6,7-Dim et h oxy-4-q u in a zolin yl)-N-t et r a h yd r o-
fu r fu r yl-1-piper azin eth iocar boxam ide (6v). 88% by method
H; mp 195-196 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR, Anal.
(C20H27N5O3S 0.25H2O) C, H, N.
N-Cycloh exylm eth yl-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin et h ioca r b oxa m id e (6w ). 73% by method H;
mp 170-171 °C (EtOAc), 1H NMR, FABMS, IR, Anal.
(C22H31N5O2S) C, H, N.
N-Cya n o-4-(6,7-d im eth oxy-4-qu in a zolin yl)-1-p ip er a zi-
n eca r boxim id ic Acid P h en yl Ester (7a ). A mixture of 2
(1.00 g, 3.65 mmol) and commercially available diphenyl
cyanocarbonimidate (0.96 g, 4.03 mmol) in 2-propanol (25 mL)
solution was refluxed for 12 h. After the reaction mixture was
cooled, the resulting precipitate was collected, washed with
2-propanol, and dried to provide 7a (0.70 g, 1.67 mmol) in 46%
yield; mp 204-205 °C (EtOAc), 1H NMR, FABMS, Anal.
(C22H22N6O3) C, H, N.
N-Cya n o-4-(6,7-d im eth oxy-4-qu in a zolin yl)-1-p ip er a zi-
n eca r boxim id ic Th io Acid Meth yl Ester (7b). A mixture
of 2 (5.00 g, 18.2 mmol) and commercially available S,S′-
dimethyl-N-cyanodithioimide carbonate (3.26 g, purity 90%,
20.1 mmol) in ethanol (30 mL) solution was refluxed for 14.5
h. After the reaction mixture was cooled, the resulting
precipitate was collected, washed with ethanol, and dried to
provide 7b (5.69 g, 15.3 mmol) in 84% yield; 1H NMR, FABMS.
4-[4-(2,2-Dicya n o-1-m et h ylt h iovin yl)-1-p ip er a zin yl]-
6,7-d im eth oxyqu in a zolin e (8). A mixture of 2 (5.00 g, 18.2
mmol) and commercially available [bis(methylthio)methylene]-
propanedinitrile (3.40 g, 20.0 mmol) in acetonitrile (50 mL)
solution was heated at 50 °C for 9 h and then refluxed for 4.5
h. After the reaction mixture was cooled to room temperature,
the resulting precipitate was collected, washed with acetoni-
trile, and dried to provide 8 (6.17 g, 15.6 mmol) in 85% yield;
mp 210-211 °C (EtOAc), 1H NMR, FABMS, IR, Anal.
(C19H20N6O2S) C, H, N.
1
1.20 mmol) in 67% yield; mp 231-233 °C (CHCl3-iPr2O), H
NMR, FABMS, IR, Anal. (C19H21N5O3S) C, H, N.
4-(6,7-Dim eth oxyqu in a zolin yl)-N-(3-th ien yl)-1-p ip er a -
zin eca r boxa m id e (4q). Quantitative yield by method D.
Analytical sample was obtained by recrystallization from
toluene; mp 239-241 °C (toluene), 1H NMR, FABMS, IR, Anal.
(C19H21N5O3S) C, H, N.
Hyd r och lor id e (4u ). To a 0 °C suspension of free base 4q
(1.50 g, 3.76 mmol) in EtOAc (50 mL) was added 4 mol/L
hydrogen chloride in EtOAc solution (9.40 mL, 37.6 mmol).
After the mixture was stirred for 30 min at the same temper-
ature, the resulting precipitate was collected, washed with cold
EtOAc, and dried to provide hydrochloride 4u (1.63 g, 3.74
mmol) in 99% yield. Analytical sample was obtained by
recrystallization from water; mp 231-232 °C (H2O), 1H NMR,
FABMS, IR, Anal. (C19H21N5O3S HCl H2O) C, H, N.
4-(6,7-Dim eth oxy-4-qu in a zolin yl)-N-(3-th ien ylm eth yl)-
1-p ip er a zin eca r boxa m id e (4r ). 48% by method F; mp 178-
179 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C20H23N5O3S
0.25H2O) C, H, N.
6,7-Dim eth oxy-4-[4-(1-m eth ylth io-2-n itr ovin yl)-1-p ip -
er a zin yl]qu in a zolin e (9). A mixture of 2 (6.00 g, 21.9 mmol)
and commercially available 1,1-bis(methylthio)-2-nitroethylene
(4.27 g, 25.8 mmol) in ethanol (30 mL) solution was heated at
50 °C for 9 h and then refluxed for 2.5 h. The residue after

4522 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 20
Matsuno et al.
the removal of solvent was purified by silica gel column
chromatography to provide 9 (2.65 g, 6.78 mmol) in 31% yield;
mp 168-172 °C (EtOAc), 1H NMR, FABMS, Anal. (C17H21N5O4S
H2O) C, H, N.
washed with water, dried, and purified by silica gel column
chromatography eluting with EtOAc/CHCl3/MeOH 50:10:4 to
provide amorphous 4s (846 mg, 1.74 mmol) in 81% yield; H
1
NMR, FABMS, IR.
N-(4-Ch lor ob en zyl)-N′-cya n o-4-(6,7-d im et h oxy-4-q u i-
n a zolin yl)-1-p ip er a zin eca r boxa m id in e (10a ). A mixture
of 7a (438 mg, 1.05 mmol) and 4-chlorobenzylamine (0.64 mL,
5.26 mmol) in ethanol (10 mL) solution was refluxed for 7.5 h.
The residue after the removal of solvent was purified by silica
gel column chromatography to provide 10a (0.39 g, 0.83 mmol)
in 79% yield; mp 218-219 °C (EtOAc), H NMR, FABMS, IR,
Anal. (C23H24ClN7O2) C, H, N.
N-Cya n o-4-(6,7-d im eth oxy-4-qu in a zolin yl)-1-p ip er a zi-
n eca r boxim id ic Acid Eth yl Ester was also obtained (66.7
mg, 0.18 mmol) together with 10a in 17% yield; 1H NMR,
FABMS.
N-Ben zyl-4-(6,7-d im eth oxy-4-qu in a zolin yl)-N-m eth yl-
1-p ip er a zin eth ioca r boxa m id e (6y). From N-methylbenzyl-
amine and 2 by method I in 58% yield; mp 158-159 °C
1
(EtOAc), H NMR, FABMS, IR, Anal. (C23H27N5O2S) C, H, N.
(RS)-4-(6,7-Dim eth oxy-4-qu in a zolin yl)-2-m eth yl-N-(4-
p h en oxyp h en yl)-1-p ip er a zin eca r b oxa m id e (17). (1) A
mixture of (RS)-2-methylpiperazine (4.46 g, 44.5 mmol) and
4-chloro-6,7-dimethoxyquinazoline (13)25 (2.00 g, 8.91 mmol)
in 2-propanol (30 mL) was refluxed for 18 h. The reaction
mixture was evaporated, and the residue was dissolved in
brine, extracted with dichloromethane, washed with brine,
dried over anhydrous sodium sulfate, and evaporated to
provide (RS)-6,7-dimethoxy-4-(3-methyl-1-piperazinyl)quinazo-
line (14) (1.35 g, 4.69 mmol) in 53% yield. (2) Reaction of 14
(445 mg, 1.55 mmol) and 4-phenoxyphenylisocyanate (0.39 g,
1.85 mmol) in dichloromethane provide 17 (372 mg, 0.75 mmol)
1
N -(3-C h lo r o b e n zy l)-N ′-c y a n o -4-(6,7-d im e t h o x y -4-
qu in a zolin yl)-1-p ip er a zin eca r boxa m id in e (10b). A mix-
ture of 7a (0.50 g, 1.20 mmol) and 3-chlorobenzylamine (0.44
mL, 3.60 mmol) in 2-propanol (10 mL) solution was refluxed
for 6 h. The residue after the removal of solvent was purified
by silica gel column chromatography to provide 10b (0.53 g,
1
in 48% yield; mp 231-232 °C (EtOAc), H NMR, FABMS, IR,
Anal. (C28H29N5O4 0.25H2O) C, H, N.
1
1.14 mmol) in 95% yield; mp 209-211 °C (EtOAc), H NMR,
(RS)-4-(6,7-Dim eth oxy-4-qu in a zolin yl)-(tr a n s-2,5-d im -
et h yl)-N-(4-p h en oxyp h en yl)-1-p ip er a zin eca r b oxa m id e
(18). (1) Reaction of excess (RS)-trans-2,5-dimethylpiperazine
and 13 in 2-propanol provide (RS)-4-(trans-2,5-dimethyl-1-
piperazinyl)-6,7-dimethoxyquinazoline (15) in 95% yield;
TOFMS (m/z): 303 (M + H)+. (2) Reaction of 15 and benzyl-
isothiocyanate provide 18 in 51% yield; mp 182-184 °C
(EtOAc), 1H NMR, FABMS, IR, Anal. (C29H31N5O4 0.25H2O)
C, H, N.
N-Ben zyl-4-(6,7-d im et h oxy-4-q u in a zolin yl)-(cis-2,6-
d im eth yl)-1-p ip er a zin eth ioca r boxa m id e (19). (1) Reaction
of excess cis-2,6-dimethylpiperazine and 13 in 2-propanol
provide 4-(cis-3,5-dimethyl-1-piperazinyl)-6,7-dimethoxyquinazo-
line (16) in 92% yield; TOFMS (m/z): 303 (M + H)+. (2)
Reaction of 16 and benzylisothiocyanate provide 19 in 90%
yield; mp 165-166 °C (EtOAc), 1H NMR, FABMS, IR, Anal.
(C24H29N5O2S) C, H, N.
FABMS, IR, Anal. (C23H24ClN7O2) C, H, N.
N -(2-C h lo r o b e n zy l)-N ′-c y a n o -4-(6,7-d im e t h o x y -4-
qu in a zolin yl)-1-p ip er a zin eca r boxa m id in e (10c). A mix-
ture of 7b (0.60 g, 1.61 mmol) and 2-chlorobenzylamine (0.97
mL, 8.04 mmol) in ethanol (10 mL) solution was refluxed for
10 h. Followed by further addition of 2-chlorobenzylamine (0.97
mL, 8.04 mmol), the mixture was refluxed for 6.5 h. The
residue after the removal of solvent was purified by silica gel
column chromatography to provide 10c (0.73 g, 1.57 mmol) in
98% yield; mp 227-228 oC (EtOAc), 1H NMR, FABMS, IR,
Anal. (C23H24ClN7O2 0.5H2O) C, H, N.
N′-Cya n o-4-(6,7-d im eth oxy-4-qu in a zolin yl)-N-(4-m eth -
ylben zyl)-1-p ip er a zin eca r boxa m id in e (10d ). From 7a and
4-methylbenzylamine in 2-propanol reflux in 81% yield; mp
215-216 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C24H27N7O2)
C, H, N.
N′-Cya n o-4-(6,7-d im et h oxy-4-q u in a zolin yl)-N-(4-iso-
p r op ylben zyl)-1-p ip er a zin eca r boxa m id in e (10e). From 7a
and 4-isopropylbenzylamine in 2-propanol reflux in 69% yield;
mp 176-177 °C (iPrOH), 1H NMR, FABMS, IR, Anal.
(C26H31N7O2 0.5iPrOH) C, H, N.
N ′-Cya n o-4-(6,7-d im e t h oxy-4-q u in a zolin yl)-N -(3,4-
m eth ylen edioxyben zyl)-1-piper azin ecar boxam idin e (10f).
From 7b and piperonylamine in pyridine at 80 °C in 25% yield;
mp 217-218 °C (EtOAc), 1H NMR, FABMS, IR, Anal.
(C24H25N7O4) C, H, N.
4-(6,7-Dim eth oxy-4-qu in azolin yl)-N-(4-ph en oxyph en yl)-
1-h om op ip er a zin eca r boxa m id e (21). Reaction of 2025 and
4-phenoxyphenylisocyanate provide 21 in 95% yield; mp 93-
96 °C (CHCl3-iPr2O), 1H NMR, FABMS, IR (KBr), Anal.
(C28H29N5O4 0.5H2O) C, H, N.
Su p p or tin g In for m a tion Ava ila ble: Spectral and el-
emental analysis data for the compounds in this study. This
material is available free of charge via the Internet at http://
pubs.acs.org.
4-{4-[1-(4-Ch lor oben zyla m in o)-2,2-d icya n ovin yl]-1-p ip -
er a zin yl}-6,7-d im eth oxyqu in a zolin e (11). From 7c and
4-chlorobenzylamine in acetonitrile reflux in 62% yield; mp
Refer en ces
242-243 °C (EtOAc), 1H NMR, FABMS, IR, Anal. (C25H24
ClN7O2 0.25H2O) C, H, N.
-
(1) Fretto, L. J .; Snape, A. J .; Tomlinson, J . E.; Seroogy, J . J .; Wolf,
D. L.; LaRochelle, W. J .; Giese, N. A. Mechanism of platelet-
derived growth factor (PDGF) AA, AB, and BB binding to alpha
and beta PDGF receptor. J . Biol. Chem. 1993, 268, 3625-3631.
(2) Heldin, C. H.; Ostman, A.; Eriksson, A.; Siegbahn, A.; Claesson-
Welsh, L.; Westermark, B. Platelet-derived growth factor: iso-
form-specific signaling via heterodimeric or homodimeric recep-
tor complexes. Kidney Int. 1992, 41, 571-574.
6,7-Dim eth oxy-4-{4-[1-(3,4-m eth ylen ed ioxyben zyla m i-
n o)-2-n itr ovin yl]-1-p ip er a zin yl}qu in a zolin e (12). From 7d
and piperonylamine in pyridine at 80 °C in 8% yield; mp 208-
1
210 °C (EtOAc), H NMR, FABMS, IR, Anal. (C24H26N6O6) C,
H, N.
(3) Herren, B.; Rooney, B.; Weyer, K. A.; Iberg, N.; Schmid, G.; Pech,
M. Dimerization of extracellular domains of platelet-derived
growth factor receptors. A revised model of receptor-ligand
interaction. J . Biol. Chem. 1993, 268, 15088-15095.
(4) Stoddard, B. L.; Biemann, H. P.; Koshland, D. E., J r. Receptors
and transmembrane signaling. Cold Spring Harb. Symp. Quan-
tum Biol. 1992, 57, 1-15.
(5) Bonner, J . C.; Lindroos, P. M.; Rice, A. B.; Moomaw, C. R.;
Morgan, D. L. Induction of PDGF receptor-alpha in rat myofi-
broblasts during pulmonary fibrogenesis in vivo. Am. J . Physiol.
1998, 274, L72-80.
(6) Friedman, S. L. Molecular regulation of hepatic fibrosis, an
integrated cellular response to tissue injury. J . Biol. Chem. 2000,
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N-(4-Ch lor oben zoyl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
1-p ip er a zin eth ioca r boxa m id e (6x). 15% by method H; mp
1
166-168 °C (CHCl3-iPr2O), H NMR, FABMS, HRMS-FAB,
IR, Anal. (C22H22ClN5O3S 0.25iPr2O 0.5H2O) C, H, N.
N -(4-C h lo r o b e n ze n e s u lfo n y l)-4-(6,7-d im e t h o x y -4-
q u in a zolin yl)-1-p ip er a zin eca r b oxa m id e (4s). 67% by
1
method A; mp 228-234 °C (CHCl3-MeOH-iPr2O), H NMR,
FABMS, HRMS-FAB, IR.
N-(4-Br om op h en yl)-4-(6,7-d im eth oxy-4-qu in a zolin yl)-
N-m eth yl-1-p ip er a zin eca r boxa m id e (4t). After a mixture
of 1c24 (1.01 g, 2.15 mmol) and NaH (60% suspension in
mineral oil, 171.9 mg, 4.30 mmol) in DMF (15 mL) was stirred
for 30 min at room temperature, iodomethane (0.27 mL, 4.34
mmol) was added. The reaction mixture was poured into water;
then NaCl was added. The resulting precipitate was collected,
(7) Gesualdo, L.; Pinzani, M.; Floriano, J . J .; Hassan, M. O.; Nagy,
N. U.; Schena, F. P.; Emancipator, S. N.; Abboud, H. E. Platelet-
derived growth factor expression in mesangial proliferative
glomerulonephritis. Lab. Invest. 1991, 65, 160-167.

Inhibitors of PDGF Receptor Phosphorylation
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(8) Heldin, C. H.; Westermark, B. Platelet-derived growth factor:
mechanism of action and possible in vivo function. Cell. Regul.
1990, 1, 555-566.
(23) Matsuno, K.; Nakajima, T.; Tahara, T.; Fujiwara, S.; Ichimura,
M.; Giese, N. A.; Yu, J .-C.; Irie, J .; Tsukuda, E.; Ide, S.-i.; Oda,
S.; Nomoto, Y. Selective inhibitor of PDGF receptor phosphory-
lation. Synthesis, structure activity relationships and biological
effects. In Proceedings of the 217th National Meeting of the
American Chemical Society, Anaheim, CA, Mar 21-25, 1999;
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61.
(24) Matsuno, K.; Ichimura, M.; Nakajima, T.; Tahara, K.; Fujiwara,
S.; Kase, H.; Giese, N. A.; Pandey, A.; Scarborough, R. M.; Yu,
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