A novel class of orally active non-peptide bradykinin B2 receptor antagonists. 4. Discovery of novel frameworks mimicking the active conformation

Article abstract of DOI:10.1021/jm980330i

In recent articles we reported the identification of a series of 8- [[2,6-dichloro-3-[N-methyl-N-[(E)- (substituted)acryloylglycyl]amino]benzyl]oxy]-2-methylimidazo[1,2- a]pyridines as the first orally active non-peptide bradykinin (BK) B₂ rece

Full text of DOI:10.1021/jm980330i

J . Med. Chem. 1998, 41, 4587-4598
4587
A Novel Cla ss of Or a lly Active Non -P ep tid e Br a d yk in in B2 Recep tor
An ta gon ists. 4. Discover y of Novel F r a m ew or k s Mim ick in g th e Active
Con for m a tion
Yoshito Abe,† Hiroshi Kayakiri,*,† Shigeki Satoh,† Takayuki Inoue,† Yuki Sawada,† Noriaki Inamura,‡
Masayuki Asano,§ Ichiro Aramori,| Chie Hatori,§ Hiroe Sawai,§ Teruo Oku,† and Hirokazu Tanaka
Exploratory Research Laboratories, Fujisawa Pharmaceutical Ltd., 5-2-3, Tokodai, Tsukuba, Ibaraki 300-2698, J apan
Received May 27, 1998
In recent articles we reported the identification of a series of 8-[[2,6-dichloro-3-[N-methyl-N-
[(E)-(substituted)acryloylglycyl]amino]benzyl]oxy]-2-methylimidazo[1,2-a]pyridines as the first
orally active non-peptide bradykinin (BK) B2 receptor antagonists. Optimization of the terminal
glycine part and the imidazo[1,2-a]pyridine moiety led to the discovery of a clinical candidate
(5, FR173657). With the aim of completion of the structure-activity relationship (SAR) study,
we next investigated the roles of the substituents on the central phenyl ring. The results
suggested that the 2,6-dichloro or 2,6-dimethyl groups may play important roles in regulating
the conformations of the 1- and 3-substituents and also may interact with hydrophobic pockets
of the B2 receptors. Furthermore, according to the results of a molecular modeling study
reported in part 1 of this series, we designed and synthesized a series of sterically constrained
analogues by replacing the N-methylamide group with cis-amide-like rigid moieties. We
discovered several bioisosteres and chemically proved that the N-methylamide moiety adopts
the cis-amide form in the active conformation. Extensive chemical modification led to the
identification of a novel class of highly potent and orally active non-peptide B2 antagonists
represented by a pyrrole derivative (52a , FR193517). Compound 52a inhibited the specific
binding of [3H]BK to recombinant human B2 receptors expressed in Chinese hamster ovary
(CHO) cells and guinea pig ileum membrane preparations expressing B2 receptors with IC50s
of 0.37 and 0.56 nM, respectively. This compound also displayed excellent in vivo functional
antagonistic activity against BK-induced bronchoconstriction in guinea pigs at 1 mg/kg by oral
administration.
In tr od u ction
oxy]-3-halo-2-methylimidazo[1,2-a]pyridines represented
by compounds 1-3 as the first orally active non-peptide
BK B2 receptor antagonists (Chart 1).20 Although their
affinities for human B2 receptors were found to be much
lower, discovery of novel key pharmacophores enabled
us to overcome the species difference between humans
and guinea pigs and to enhance the in vivo activities
leading to the identification of 4 (FR167344).21,22 Fur-
thermore, intensive research seeking bioisosteres of the
imidazo[1,2-a]pyridine ring afforded the quinoline de-
rivatives 5 (FR173657)21b,23,24 and 6 (FR184280)24 with
highly potent in vitro and excellent in vivo activities. A
molecular modeling study in part 1 of this series had
suggested that the N-methylamide group at the 3-posi-
tion of the 2,6-dichlorobenzene ring adopts a cis-amide
form as the active conformation.20 To verify this sug-
gested active conformation, we designed and synthe-
sized a series of sterically constrained analogues by
replacing the N-methylamide group with cis-amide-like
rigid moieties and discovered several promising bioi-
sosteres. Herein we wish to describe the structure-
activity relationship (SAR) revealed on the way to the
discovery of a new series of highly potent and orally
active non-peptide BK B2 receptor antagonists which
incorporate a novel framework mimicking the active
conformation.
Bradykinin (BK) is an endogenous proinflammatory
nonapeptide which is believed to play important roles
in pain, inflammation, asthma, rhinitis, and hypoten-
sion.1-8 Two types of kinin receptors, designated as B1
and B2, have been identified by molecular cloning and
pharmacological methods,1,4,9-11 and most of the biologi-
cal actions of BK are mediated by B2 receptors.1,9 Since
BK B2 receptor antagonists have therapeutic potential
as novel analgesics and antiinflammatory agents, a
number of antagonists have been investigated.12-16 The
second-generation peptide B2 antagonists, including
Icatibant (Hoe140),12,13 have highly potent affinity for
B2 receptors; however, therapeutic use is still limited
because of their peptidic nature. On the other hand,
few non-peptide antagonists have been disclosed.17-19
Indeed, until our work20 there were no reports of orally
active non-peptide B2 antagonists.
Recently, we reported the identification of a series of
8-[[3-(N-acylglycyl-N-methylamino)-2,6-dichlorobenzyl]-
† Department of Medicinal Chemistry.
§ Department of Pharmacology.
|| Molecular Biological Research Laboratory.
‡ Present address: Exploratory Clinical Research, Development
Division, Fujisawa Pharmaceutical Co. Ltd., 2-1-6, Kashima, Yo-
dogawa-ku, Osaka 532-8514, J apan.
Present address: New Drug Research Laboratories, Fujisawa
Pharmaceutical Co. Ltd., 2-1-6, Kashima, Yodogawa-ku, Osaka 532-
8514, J apan.
10.1021/jm980330i CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/08/1998

4588 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23
Abe et al.
Ch a r t 1
Sch em e 1a
a
(a) MsCl, Et3N, CH2Cl2; (b) NaH, DMF; (c) N2H4‚H2O, FeCl3‚6H2O, C, aqueous MeOH; (d) Fe, AcOH, EtOH; (e) N-phthaloylglycyl
chloride, pyridine, DMF; (f) MeI, NaH, DMF; (g) N2H4‚H2O, EtOH; (h) (E)-4-(N-methylcarbamoyl)cinnamic acid or (E)-3-(6-acetamidopyridin-
3-yl)acrylic acid, WSCD‚HCl, HOBt, DMF.
Ch em istr y
obtained from 10a -d by coupling with N-phthaloyl-
glycyl chloride in pyridine and DMF. Alkylation of
11b-d with methyl iodide in the presence of sodium
hydride yielded 12b-d . The N-phthaloyl groups of 10a
and 12b-d were deprotected with hydrazine monohy-
drate followed by coupling with (E)-4-(N-methylcarbam-
oyl)cinnamic acid22 or (E)-3-(6-acetamidopyridin-3-yl)-
acrylic acid22 in the presence of 1-ethyl-3-(dimethyl-
aminopropyl)carbodiimide hydrochloride (WSCD‚HCl)
and 1-hydroxybenzotriazole (HOBt) to give the acryla-
mides 14b-e.
The compounds described in this study are shown in
Tables 1-3, and their synthetic methods are outlined
in Schemes 1-6.
Modification of the substituents at the 2,6-dichlo-
robenzene ring and the N-methylamide group is shown
in Scheme 1. Appropriate benzyl alcohols 7a -d were
treated with methanesulfonyl chloride and triethyl-
amine in CH2Cl2, and subsequent coupling with 2-meth-
yl-8-hydroxyquinoline (8) in the presence of sodium
hydride as a base gave the corresponding quinolines
9a -d , respectively. Reduction of the nitro group with
hydrazine monohydrate, iron(II) chloride hexahydrate,
and carbon or iron in AcOH and EtOH gave the anilines
10a -d . The N-phthaloylglycinamides 11a -d were
Schemes 2-6 show the synthetic routes for the
various cis- or trans-amide-like rigid moieties, which
were introduced in place of the N-methylamide group.
Replacement of the N-methylamide group with a double

Orally Active Non-Peptide BK B2 Receptor Antagonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23 4589
Sch em e 2a
a
(a) n-BuLi, DMF, THF; (b) NaBH4, MeOH; (c) MsCl, Et3N, CH2Cl2; (d) 8, NaH, DMF; (e) AcOH, H2O; (f) 2-(N-phthaloyl)ethyltri-
phenylphosphonium bromide, NaH, DMSO; (g) N2H4‚H2O, EtOH; (h) (E)-4-(N-methylcarbamoyl)cinnamic acid, WSCD‚HCl, HOBt, DMF.
Sch em e 3a
Sch em e 4a
a
(a) 3-Aminophenylboronic acid hemisulfate, 2 M Na2CO3,
Pd(PPh3)4, toluene; (b) (E)-4-(N-methylcarbamoyl)cinnamic acid,
WSCD‚HCl, HOBt, DMF; (c) n-Bu4NF, THF; (d) MsCl, Et3N,
CH2Cl2; (e) 8, NaH, DMF.
a
(a) n-BuLi, ZnCl2, 2-bromobenzonitrile, Pd(PPh3)4, THF; (b)
n-Bu4NF, THF; (c) MsCl, Et3N, CH2Cl2; (d) 8, NaH, DMF; (e) LAH,
THF; (f) (E)-4-(N-methylcarbamoyl)cinnamic acid, WSCD‚HCl,
HOBt, DMF.
place of the N-methylamide group is illustrated in
Scheme 3. Coupling of the bromobenzene 24 with
2-bromobenzonitrile and subsequent deprotection of the
silyl group with tetra-n-butylammonium fluoride pro-
vided the benzyl alcohol 26. Treatment of 26 with
methanesulfonyl chloride, coupling with 8, reduction of
the cyano group of 27 with lithium aluminum hydride,
and condensation with (E)-4-(N-methylcarbamoyl)cin-
namic acid22 gave the cinnamamide 29a .
Scheme 4 shows replacement of the N-methylamide
group with a 1,3-disubstituted benzene ring. Suzuki
coupling of 24 with 3-aminophenylboronic acid hemisul-
fate in the presence of tetrakis(triphenylphosphine)-
palladium(0), condensation with (E)-4-(N-methylcar-
bamoyl)cinnamic acid,22 and deprotection of the silyl
group afforded the benzyl alcohol 32. Reaction of 32
with methanesulfonyl chloride and alkylation with 8
yielded the quinoline 29b.
bond is shown in Scheme 2. Treatment of 2-(2,4-
dichlorophenyl)-1,3-dioxolane (16) with n-butyllithium
followed by reaction with DMF gave the benzaldehyde
17. Reduction of 17 with sodium borohydride provided
the benzyl alcohol 18, which was treated with meth-
anesulfonyl chloride followed by coupling with 8 to
afford the quinoline 19. Deprotection of the 1,3-diox-
olane group of 19 under acidic conditions, followed by
Wittig reaction using sodium hydride and DMSO, gave
a 3:4 mixture of (Z)- and (E)-isomers (21a ,b), whose
stereochemistry was identified on the basis of the
observed coupling constants of 10 and 15 Hz between
the olefinic protons for (Z)- and (E)-isomers, respectively.
The N-phthaloyl groups of 21a ,b were removed, and the
resultant amines 22a ,b were condensed with (E)-4-(N-
methylcarbamoyl)cinnamic acid22 in the presence of
WSCD‚HCl and HOBt to furnish the cinnamamides
23a ,b.
Synthesis of the thienyl derivative was performed as
shown in Scheme 5. Coupling of 24 with 3-bromo-2-
cyanothiophene, reduction of the cyano group with
Introduction of the 1,2-disubstituted benzene ring in

4590 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23
Abe et al.
Sch em e 5a
carbamoyl 47. The acrylamides 42-45 and 47-49 were
converted to the corresponding hydrochlorides 50a -55a ,
respectively.
Biology
All compounds were tested for inhibition of the
specific binding of [3H]BK to B2 receptors in guinea pig
ileum membrane preparations as previously re-
ported,20-23a,24 and they were also evaluated for inhibi-
tion of the specific binding of [3H]BK to human recom-
binant B2 receptors expressed in CHO cells.21b,24 Com-
pounds having potent binding affinities were then tested
for in vivo functional antagonistic activity in inhibiting
BK-induced bronchoconstriction in guinea pigs by oral
administration.20,21a,22,23a,24
Resu lts a n d Discu ssion
a
(a) n-BuLi, ZnCl2, 3-bromo-2-cyanothiophene, Pd(PPh3)4, THF;
(b) BH3‚THF, THF; (c) (E)-4-(N-methylcarbamoyl)cinnamic acid,
WSCD‚HCl, HOBt, DMF; (d) n-Bu4NF, THF; (e) MsCl, Et3N,
CH2Cl2; (f) 8, NaH, DMF.
Recently, we reported the first series of orally active
non-peptide BK B2 receptor antagonists, incorporating
a 8-[[3-(N-acylglycyl-N-methylamino)-2,6-dichloroben-
zyl]oxy]-3-halo-2-methylimidazo[1,2-a]pyridine skeleton
as the basic framework.20 Using the representatives
(1-3) as lead compounds, we then investigated SAR for
B2 binding affinities to both human and guinea pig
receptors and demonstrated an obvious species differ-
ence in the ligand selectivity. Intensive chemical modi-
fication of the terminal amide part (C part in Chart 1)
led to identification of the essential pharmacophores for
human B2 binding affinity and to speculation of their
interaction with B2 receptors.22 Further extensive
research on the imidazo[1,2-a]pyridine part (A part) led
to several bioisosteres and resulted in the identification
of the highly potent quinoline series.24 Thus, we have
discovered a novel class of potent, selective, and orally
active non-peptide B2 antagonists represented by 4,21,22
5,21b,23,24 and 6.24 To complete the SAR of our B2
antagonists, we next aimed to elucidate the roles of each
substituent on the central phenyl ring in the B part.
At first we investigated replacement of the chloro
atoms in the B part. 2,6-Dimethyl derivative 15 re-
tained high B2 binding affinities, while the 2,6-dimethoxy
congener 14b showed 191- and 33-fold decreased activ-
ity against the human and guinea pig receptors, respec-
tively (Table 1). Removal of the 2-chloro atom from 14a
and the 6-methyl group from 15 resulted in greater loss
of B2 binding affinity to the human receptor (100- and
31-fold) than to the guinea pig one (10- and 18-fold).
These results suggest that both the 2- and 6-chloro or
-methyl groups may be important, not only for confor-
mational restriction of the 1- and 3-substituents but also
for hydrophobic interactions with B2 receptors. We next
examined the steric effect of the N-substituent R3.
Removal of the N-methyl group from 5 gave 14e which
displayed a 3 orders of magnitude reduction in binding
affinity to both human and guinea pig B2 receptors,
consistent with the results in the imidazo[1,2-a]pyridine
series.20 This dramatic loss of activity may be postu-
lated to be the result of a critical conformational change
for the whole molecule. As reported in part 1 of this
series,20 a molecular modeling study suggested that the
N-methylamide preferred the cis-amide conformation,
while the trans-amide form was favorable for the N-H
amide. It was also suggested that the planes of the
N-methylamide and the 2,6-dichlorophenyl moieties
Sch em e 6a
a
(a) 2,5-Dimethoxytetrahydrofuran, AcOH, 90 °C; (b) ClSO2NCO,
DMF, CH2Cl2; (c) LAH, THF; (d) substituted acrylic acid,
WSCD‚HCl, HOBt, DMF; (e) 1
N NaOH, EtOH, 60 °C; (f)
H2NMe‚HCl, WSCD, HOBt, DMF; (g) HCl-MeOH.
borane-THF complex, and condensation with (E)-4-(N-
methylcarbamoyl)cinnamic acid22 provided 36. Depro-
tection, sulfonylation, and alkylation afforded the 2,3-
disubstituted thiophene 38.
Replacement of the N-methylamide group with the
pyrrole ring and modification of the terminal acrylamide
moiety are shown in Scheme 6. The pyrrole 39 was
obtained from 10a by heating 2,5-dimethoxytetrahy-
drofuran in AcOH. Reaction of 39 with chlorosulfonyl
isocyanate provided the 2-cyano derivative 40. The
cyano group of 40 was reduced to give the amine 41,
which was condensed with appropriate acrylic acids to
furnish the corresponding acrylamides 42-45, 48, and
49, respectively. Hydrolysis of the ester 45 followed by
coupling with methylamine hydrochloride yielded the

Orally Active Non-Peptide BK B2 Receptor Antagonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23 4591
Ta ble 1. Modification of Substituents at the 2,6-Dichlorobenzene Ring
a
Concentration required to inhibit specific binding of [3H]BK (0.06 nM) to B2 receptors in guinea pig ileum membrane preparations by
50%. Values are expressed as the average of at least three determinations, with variation in individual values of <15%. See the Experimental
b
Section for further details. Concentration required to inhibit specific binding of [3H]BK (1.0 nM) to human B2 receptors which was
expressed in CHO (Chinese hamster ovary) cells by 50%. Values are expressed as the average of at least three determinations, with
variation in individual values of <15%. See the Experimental Section for further details. c Analyses for C, H, and N are within (0.4% of
the expected value for the formula.
were almost perpendicular, whereas those of the N-H
amide and the 2,6-dichlorophenyl moieties were almost
coplanar. Such a conformational change at the central
anilide can cause significant topological differences in
the important pharmacophores in the C part. On this
point, it seems reasonable that the B2 binding affinity
for human receptors is more sensitive to chemical
modification of the B part than that for guinea pig
receptors, because the terminal pharmacophore of the
C part is essential for the former but not so important
for the latter. These results prompted us to design and
synthesize sterically constrained derivatives by replac-
ing the N-methylamide group with cis-amide-like rigid
moieties.
ing to some degree to the trans-amide form, resulted in
complete loss of human B2 affinity and a 184-fold
decrease in guinea pig activity. Furthermore, we in-
vestigated substitution of the benzene ring of 29a with
five-membered rings. Bioisosteric conversion of the 1,2-
disubstituted phenyl ring of 29a to a 2,3-disubstituted
thienyl derivative (38) retained activity. On the other
hand, a pyrrole derivative (50a ) afforded a remarkable
increase in binding affinities, to both human and guinea
pig receptors, with IC50s of 0.26 and 0.64 nM, respec-
tively. These results revealed that the cis-N-methyla-
mide moiety, along with the 2,6-dichloro group, play key
roles to allow the whole molecule to adopt the charac-
teristic active conformation.
Table 2 summarizes the results of the bioisosteric
transformation of the N-methylamide group into rigid
moieties mimicking cis- and trans-conformers. Upon
replacement of the N-methylamide group by a double
bond, the cis-isomer (23a ) exhibited 51-fold more potent
human B2 binding affinity compared with the corre-
sponding trans-isomer (23b), supporting the results of
the molecular modeling study. Although binding affin-
ity to both receptors was lower for 23a compared to
N-methylamide derivative 14a , this might be due to
insufficient steric features to regulate the molecule to
adopt the active conformation. Next we replaced the
N-methylamide group with bulkier aromatic rings.
Introduction of a 1,2-disubstituted benzene ring (29a ),
corresponding to the cis-amide form, recovered binding
affinities to the same level as 14a , while replacement
with a 1,3-disubstituted benzene ring (29b), correspond-
For optimization of the pyrrole series, we investigated
introduction of several acrylic acid moieties to the C
part, which afforded potent binding affinities for both
human and guinea pig B2 receptors in the N-methyla-
mide series. Table 3 shows a comparison of these
pyrrole derivatives with the corresponding N-methyla-
mide congeners. All pyrroles exhibited highly potent
binding affinities for both species. Although the pyrrole
derivatives tend to be weaker in vivo, compounds 51a ,
52a , and 53a retained excellent antagonistic activities.
It is noteworthy that most of the pyrroles afforded a
3-10-fold increase in human B2 binding activity com-
pared with the N-methylamide counterparts. In par-
ticular, compound 50a is almost twice as potent as the
second-generation peptide B2 antagonist, Icatibant.
These results indicate that the SAR at the terminal
substituent in the pyrrole series is consistent with that

4592 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23
Ta ble 2. Modification of the N-Methylacetamide Moiety
Abe et al.
a-c See corresponding footnotes in Table 1.
in the N-methylamide series and that the pyrrole
derivatives bind to human B2 receptors in a similar but
conformationally more refined mode compared with the
N-methylamide bioisosteres.
amide-like rigid moieties and found that it could be
successfully replaced by several bioisosteres. Thus, we
have chemically proven that the active conformation of
the N-methylamide moiety for both guinea pig and
human B2 receptors is the cis-amide form. Extensive
optimization of these new heteroaromatic derivatives
allowed us to identify a novel series of highly potent and
orally active non-peptide B2 antagonists, incorporating
a pyrrole moiety instead of the N-methylamide group.
Several pyrrole derivatives exhibited equipotent binding
affinities for human B2 receptors to the second-genera-
tion peptide B2 antagonist, Icatibant. Since the repre-
sentative pyrrole 52a afforded highly potent B2 binding
affinities to both human and guinea pig receptors, with
IC50 values of 0.37 and 0.56 nM, respectively, along with
an excellent in vivo antagonistic activity at 1 mg/kg po,
it is expected to be a novel class of drug for various
inflammatory diseases.
Con clu sion
In this study we investigated the roles of substituents
on the central phenyl ring in the B part to complete the
SAR of our non-peptide B2 antagonists. The results
suggested that the 2,6-dichloro substituents may play
important roles not only to regulate the conformation
of the 1- and 3-substituents but also to interact with
the corresponding hydrophobic pockets of the B2 recep-
tors and that the 3-N-methylamide moiety may critically
contribute to prescribe the conformation of the C part.
According to the results of a molecular modeling
study, reported in part 1 of this series,20 we designed
and synthesized a series of sterically constrained ana-
logues by replacing the N-methylamide group with cis-

Orally Active Non-Peptide BK B2 Receptor Antagonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23 4593
Ta ble 3. Comparison of the Pyrrole Series with the N-Methylamide Series
a,b,d
See corresponding footnotes in Table 1. c BK (5 µg/kg) was administered intravenously to anesthetized guinea pigs, and
bronchoconstriction induced by the BK administration was measured by the modified Konzett and Ro¨sseler method27 as previously reported.
After 5 min, compounds were orally administered. After 30 min, BK was administered again and bronchoconstriction was measured.
Percent inhibition was calculated from the values of percent responses of drug-treated and control groups (n ) 3-4). The results are
expressed as the mean ( SEM. *p < 0.05, **p < 0.01, ***p < 0.001 vs control (Student’s t-test). See the Experimental Section for further
details. e NT, not tested.

4594 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23
Abe et al.
dry pyridine (2.5 mL), and N-methylpyrrolidone (7.5 mL) was
added N-phthaloylglycyl chloride (1.01 g, 4.52 mmol) at
ambient temperature under nitrogen. The reaction mixture
was then stirred at 50 °C for 2 h. To the mixture was added
dropwise water (10 mL) in an ice-water bath. The precipitate
was collected by vacuum filtration, washed with water, and
dried in vacuo. This crude solid was purified by flash silica
gel column chromatography (CHCl3-MeOH, 40:1) followed by
crystallization from AcOEt to give 11a (1.38 g, 87.9%) as pale-
yellow crystals: mp 133-135 °C; 1H NMR (CDCl3) δ 2.86 (3H,
s), 4.74 (2H, s), 5.51 (2H, s), 7.20-7.50 (5H, m), 7.63-7.93 (4H,
m), 8.03 (1H, d, J ) 8 Hz), 8.29 (1H, d, J ) 8 Hz). Anal.
(C27H19Cl2N3O4) C, H, N.
Exp er im en ta l Section
Ch em istr y. Melting points were determined on a Mel-
Temp instrument (Mitamura Riken Kogyo, J apan) and are
uncorrected. Proton NMR spectra (300 MHz) were recorded
on a Varian Gemini 300 spectrometer, and shifts are expressed
in δ (ppm) with TMS as internal standard. Mass spectra were
recorded with a VG (Fisons) ZAB-SE (FAB) or Micromass
Platform (ESI) system. Elemental analyses were performed
on a Perkin-Elmer 2400 CHN analyzer. Analytical results
were within (0.4% of the theoretical values unless otherwise
noted. Silica gel thin-layer chromatography was performed
on precoated plates Kieselgel 60F254 (E. Merck, AG, Darmstadt,
Germany). Silica gel flash chromatography was performed
with Kieselgel 60 (230-400 mesh) (E. Merck, AG, Darmstadt,
Germany). Extraction solvents were dried over magnesium
sulfate.
8-[(2,6-Dich lor o-3-n it r ob e n zyl)oxy]-2-m e t h ylq u in o-
lin e (9a ). To a solution of 7a (2.00 g, 9.01 mmol) and
triethylamine (1.19 g, 11.7 mmol) in dry CH2Cl2 (20 mL) was
added dropwise methanesulfonyl chloride (1.14 g, 9.91 mmol)
in an ice-water bath under nitrogen. After 30 min, the
reaction mixture was washed with water, saturated aqueous
sodium bicarbonate, and brine. The organic layer was dried
and evaporated in vacuo to give 2.70 g of a pale-yellow oil.
Following a similar procedure to method A, the title compound
was obtained in 87.6% yield from 8 and the preceding oil as
pale-yellow crystals after crystallization from MeOH: mp 183-
186 °C; 1H NMR (CDCl3) δ 2.76 (3H, s), 5.70 (2H, s), 7.21-
7.57 (5H, m), 7.76 (1H, d, J ) 8 Hz), 8.02 (1H, d, J ) 8 Hz).
Anal. (C17H12Cl2N2O3) C, H, N.
Compounds 11b,c were prepared using a similar procedure
to that used for 11a .
8-[[3-(N-Am in oa cetyl-N-m eth yla m in o)-2,6-d im eth oxy-
ben zyl]oxy]-2-m eth ylqu in olin e (13b). To a suspension of
12b (1.14 g, 2.17 mmol) in EtOH (11 mL) was added hydrazine
monohydrate (217 mg, 4.34 mmol) at ambient temperature,
and the mixture was refluxed for 1 h. After the reaction
mixture was cooled, the precipitates formed were filtered off.
The filtrate was evaporated in vacuo, CH2Cl2 (6 mL) was added
to the residue, and precipitates were filtered off. The filtrate
was again evaporated in vacuo and the residue purified by
flash silica gel column chromatography (CH2Cl2-MeOH, 20:
1) to give 13b (786 mg, 91.6%) as a pale-yellow amorphous
solid: 1H NMR (CDCl3) δ 2.69 (3H, s), 3.10 (1H, d, J ) 17
Hz), 3.22 (1H, d, J ) 17 Hz), 3.30 (3H, s), 3.85 (6H, s), 5.33
(1H, d, J ) 10 Hz), 5.44 (1H, d, J ) 10 Hz), 6.72 (1H, d, J )
8 Hz), 7.12 (1H, d, J ) 8 Hz), 7.21-7.45 (4H, m), 8.00 (1H, d,
J ) 8 Hz); MS (ESI) m/z 395 (M + 1). Anal. (C22H25N3O4) C,
H, N.
Compounds 9b-d , 19, 27, and 38 were prepared using a
similar procedure to that used for 9a .
8-[(3-Am in o-2,6-d ich lor ob en zyl)oxy]-2-m et h ylq u in o-
lin e (10a ). To a mixture of 9a (1.82 g, 5.00 mmol), iron(III)
chloride (55 mg), and carbon (55 mg) in 80% aqueous MeOH
(27 mL) was added dropwise hydrazine monohydrate (1.00 g,
20.0 mmol) at 70 °C. After the mixture stirred for 4 h at 70
°C, MeOH (10 mL) and hydrazine monohydrate (500 mg, 10.0
mmol) were added therein, and the mixture stirred for a
further 2 h. The reaction mixture was then cooled to ambient
temperature and filtered through Celite. The filtrate was
concentrated in vacuo, and the residue was partitioned be-
tween CHCl3 and saturated aqueous sodium bicarbonate. The
organic layer was washed with water and brine, dried, and
evaporated in vacuo. The residue was purified by flash silica
gel column chromatography (CHCl3-MeOH, 30:1) followed by
crystallization from MeOH to give 10a (1.10 g, 65.8%) as pale-
Compounds 13c-e and 22a ,b were prepared using a similar
procedure to that used for 13b.
2,6-Dich lor o-3-(2,5-d ioxola n yl)ben za ld eh yd e (17). To
a solution of 16 (31.9 g, 146 mmol) in dry THF (220 mL) was
added dropwise 1.6 M n-butyllithium in hexane (110 mL)
below -50 °C in a dry ice-acetone bath under nitrogen. After
1 h, to the reaction mixture was added dry DMF (56.4 mL,
728 mmol). After 15 min, the mixture was stirred at ambient
temperature for 1 h. The mixture was partitioned between
AcOEt (200 mL) and water (200 mL); the organic layer was
washed with water (2×), dried, and evaporated in vacuo. The
residue was purified by flash silica gel column chromatography
(hexane-AcOEt, 10:1) followed by crystallization from isopro-
pyl ether to give 17 (4.91 g, 13.6%) as colorless crystals: mp
96-98 °C; 1H NMR (CDCl3) δ 4.04-4.20 (4H, m), 6.16 (1H, s),
7.44 (1H, d, J ) 8 Hz), 7.75 (1H, d, J ) 8 Hz), 10.05 (1H, s).
Anal. (C10H8Cl2O3) C, H, N.
1
brown crystals: mp 231-234 °C; H NMR (DMSO-d6) δ 2.60
(3H, s), 5.33 (2H, s), 5.68 (2H, br s), 6.91 (1H, d, J ) 8 Hz),
7.23 (1H, d, J ) 8 Hz), 7.35-7.52 (4H, m), 8.11 (1H, d, J ) 8
Hz); MS (ESI) m/z 333 (M + 1). Anal. (C17H14Cl2N2O) C, H,
N.
2,6-Dich lor o-3-(2,5-d ioxola n yl)ben zyl Alcoh ol (18). To
a solution of 17 (3.90 g, 15.8 mol) in dry MeOH (20 mL) was
added sodium borohydride (299 mg, 7.89 mmol) portionwise
below 10 °C in an ice-water bath under nitrogen. The
reaction mixture was then stirred at the temperature for 1 h.
To the ice-cooled mixture was added dropwise water (125 mL)
and the whole extracted with AcOEt. The organic layer was
washed with water and brine, dried, and evaporated in vacuo.
The residue was purified by flash silica gel column chroma-
tography (hexane-AcOEt, 3:1) followed by crystallization from
isopropyl ether to give 18 (3.69 g, 93.8%) as colorless crystals:
mp 82-85 °C; 1H NMR (CDCl3) δ 2.08 (1H, t, J ) 7 Hz), 4.02-
4.18 (4H, m), 5.00 (2H, d, J ) 7 Hz), 6.13 (1H, s), 7.38 (1H, d,
J ) 8 Hz), 7.54 (1H, d, J ) 8 Hz); MS (ESI) m/z 249 (M + 1).
Anal. (C10H10Cl2O3) C, H, N.
Compound 10b was prepared using a similar procedure to
that used for 10a .
8-[(5-Am in o-2-ch lor ob en zyl)oxy]-2-m et h ylq u in olin e
(10c). A suspension of 9c (3.28 g, 10.0 mmol) and iron
(powder, 2.80 g, 50.0 mmol) in a mixture of AcOH (32 mL)
and EtOH (15 mL) was refluxed for 3 h. After cooling, the
mixture was filtered and washed with CH2Cl2-MeOH (4:1).
The filtrate was evaporated in vacuo, and the residue was
partitioned between CH2Cl2-MeOH (4:1) and saturated aque-
ous sodium bicarbonate. The organic layer was dried and
evaporated in vacuo and the residue purified by flash silica
gel column chromatography (CHCl3-MeOH, 50:1) followed by
crystallization from diethyl ether to give 10c (1.64 g, 54.8%)
as pale-brown crystals: mp 176-178 °C; 1H NMR (DMSO-d6)
δ 2.67 (3H, s), 5.22 (2H, s), 5.31 (2H, s), 6.55 (1H, d, J ) 8, 2
Hz), 6.80 (1H, d, J ) 2 Hz), 7.10-7.16 (2H, m), 7.37-7.48 (3H,
m), 8.19 (1H, d, J ) 8 Hz). Anal. (C17H15ClN2O) C, H, N.
Compound 10d was prepared using a similar procedure to
that used for 10c.
8-[(2,6-Dich lor o-3-for m ylb en zyl)oxy]-2-m et h ylq u in o-
lin e (20). A solution of 19 (2.00 g, 5.12 mmol) in 80% AcOH
(20 mL) was heated at 60 °C for 2 h. The cooled reaction
mixture was then concentrated in vacuo. To the residue was
added aqueous sodium bicarbonate solution, followed by
extraction with CHCl3. The organic layer was washed with
water, dried, and evaporated in vacuo. The residue was
crystallized from AcOEt to give 20 (1.53 g, 86.3%) as colorless
crystals: mp 184-186 °C; 1H NMR (CDCl3) δ 2.73 (3H, s), 5.69
8-[[2,6-Dich lor o-3-(N-p h th a lim id oa cetyla m in o)ben zyl]-
oxy]-2-m eth ylqu in olin e (11a ). To a mixture of 10a (1.00
g, 3.01 mmol), 4-(dimethylamino)pyridine (37 mg, 0.301 mmol),

Orally Active Non-Peptide BK B2 Receptor Antagonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23 4595
(2H, s), 7.23-7.52 (5H, m), 7.89 (1H, d, J ) 8 Hz), 8.02 (1H, d,
J ) 8 Hz); MS (ESI) m/z 346 (M + 1). Anal. (C18H13Cl2NO2)
C, H, N.
ylboronic acid hemisulfate (472 mg, 2.54 mmol) in toluene (11
mL) were added tetrakis(triphenylphosphine)palladium(0) (64
mg, 0.055 mmol), 2 M sodium carbonate in H2O (5.5 mL),
MeOH (2.8 mL), and 24 (1.00 g, 2.21 mmol) at ambient
temperature, and the mixture was heated at 80 °C. After 5
h, the cooled reaction mixture was extracted with CHCl3, and
the organic layer was washed with saturated aqueous sodium
bicarbonate solution and brine, dried, and evaporated in vacuo.
The residue was purified by flash silica gel chromatography
(hexane-AcOEt, 5:1) to give 30 (350 mg, 34.1%) as a pale-
yellow oil: 1H NMR (CDCl3) δ 1.05 (9H, s), 2.14 (3H, s), 2.26
(3H, s), 3.67 (2H, br s), 4.77 (2H, s), 6.56-6.80 (3H, m), 7.00
(1H, d, J ) 8 Hz), 7.06 (1H, d, J ) 8 Hz), 7.16 (1H, t, J ) 8
Hz), 7.32-7.48 (6H, m), 7.70 (4H, br d, J ) 8 Hz); MS (ESI)
m/z 466 (M + 1). Anal. (C31H35NOSi) C, H, N.
1-Ch lor om eth yl-2,6-d im eth yl-3-[3-[(E)-4-(N-m eth ylca r -
ba m oyl)cin n a m a m id oa cetyl]p h en yl]ben zen e (33). To a
solution of 32 (104 g, 0.251 mmol) and triethylamine (38 mg,
0.376 mmol) in dry DMF (1 mL) was added methanesulfonyl
chloride (34 mg, 0.297 mmol) in an ice-water bath under
nitrogen. After 30 min, the reaction mixture was stirred at
ambient temperature for 4 h. The mixture was partitioned
between CH2Cl2 and water. The organic layer was washed
with water (4×) and brine, dried, and evaporated in vacuo.
The residue was crystallized from MeCN to give 33 (102 mg,
93.9%) as colorless crystals: mp 238-241 °C; 1H NMR (DMSO-
d6) δ 2.30 (3H, s), 2.44 (3H, s), 2.79 (3H, d, J ) 5 Hz), 4.88
(2H, s), 4.78 (1H, t, J ) 6 Hz), 6.90 (1H, d, J ) 15 Hz), 6.99
(1H, br d, J ) 8 Hz), 7.09-7.21 (2H, m), 7.40 (1H, t, J ) 8
Hz), 7.58-7.74 (5H, m), 7.89 (2H, d, J ) 8 Hz), 8.50 (1H, br d,
J ) 5 Hz); MS (ESI) m/z 433 (M + 1). Anal. (C26H25ClN2O2)
C, H, N.
8-[[2,6-Dich lor o-3-[(Z)-3-(N-p h th a lim id o)p r op en yl]ben -
zyl]oxy]-2-m eth ylqu in olin e (21a ) a n d 8-[[2,6-Dich lor o-3-
[(E )-3-(N -p h t h a lim id o)p r op e n yl]b e n zyl]oxy]-2-m e t h -
ylqu in olin e (21b). A mixture of 60% sodium hydride in oil
(428 mg, 10.7 mmol) and DMSO (24 mL) was stirred at 60 °C
under nitrogen for 1 h. Tothe mixture was added 2-(N-phthaloyl)-
ethyltriphenylphosphonium bromide (5.53 g, 10.7mol) at ambi-
ent temperature. After the mixture stirred for 30 min, 20 (1.23
g, 3.55 mmol) was added therein in an ice-water bath and
stirring continued at ambient temperature overnight. To the
ice-cooled reaction mixture was added water, and the mixture
was extracted with CHCl3. The organic layer was washed with
water (3×) and brine, dried, and evaporated in vacuo. The
residue was purified by flash silica gel chromatography, eluting
with hexane-AcOEt (3:1), followed by crystallization from
isopropyl ether to give 21a (464 mg, 30.0%) as colorless
crystals. Further elution of the column with hexane-AcOEt
(1:1) followed by crystallization from isopropyl ether gave 21b
(629 mg, 35.2%) as colorless crystals. 21a : mp 187-190 °C;
1H NMR (CDCl3) δ 2.75 (3H, s), 4.42 (2H, d, J ) 7 Hz), 5.65
(2H, s), 5.83 (1H, dt, J ) 10, 7 Hz), 6.67 (1H, br d, J ) 10 Hz),
7.24-7.31 (2H, m), 7.36-7.47 (3H, m), 7.59 (1H, d, J ) 8 Hz),
7.69-7.77 (2H, m), 7.82-7.90 (2H, m), 8.01 (1H, d, J ) 8 Hz);
MS (ESI) m/z 503 (M + 1). Anal. (C28H20Cl2N2O3) C, H, N.
1
21b: mp 213-215 °C; H NMR (CDCl3) δ 2.73 (3H, s), 4.49
(2H, d, J ) 7 Hz), 5.61 (2H, s), 6.22 (1H, dt, J ) 15, 7 Hz),
7.07 (1H, br d, J ) 15 Hz), 7.20-7.30 (3H, m), 7.33-7.46 (3H,
m), 7.70-7.78 (2H, m), 7.84-7.91 (2H, m), 8.00 (1H, d, J ) 8
Hz); MS (ESI) m/z 503 (M + 1). Anal. (C28H20Cl2N2O3) C, H,
N.
Meth od A. 8-[[2,6-Dim eth yl-3-[3-[(E)-4-(N-m eth ylca r -
bam oyl)cin n am am ido]ph en yl]ben zyl]oxy]-2-m eth ylqu in -
olin e (29b). To a solution of 8 (100 mg, 0.628 mmol) in dry
DMF (2 mL) was added 60% sodium hydride in oil (27 mg,
0.659 mmol) in an ice-water bath under nitrogen. After 30
min, 33 (272 mg, 0.628 mmol) was added therein, and the
mixture stirred at ambient temperature for 2 h. The mixture
was poured into water and the precipitated solid collected by
vacuum filtration, washed with water, and dried in vacuo. The
solid was purified by flash silica gel column chromatography
(CHCl3-MeOH, 30:1), followed by crystallization from MeOH
to give 29b (250 mg, 71.6%) as colorless crystals: mp 234-
238 °C; 1H NMR (CDCl3) δ 2.31 (3H, s), 2.46 (3H, s), 2.70 (3H,
s), 2.98 (3H, s), 5.32 (2H, s), 6.74 (1H, d, J ) 15 Hz), 7.02-
7.12 (2H, m), 7.18 (1H, br d, J ) 8 Hz), 7.29-7.59 (7H, m),
7.64-7.81 (4H, m), 8.01 (1H, br d, J ) 8 Hz), 8.09 (1H, d, J )
8 Hz); MS (ESI) m/z 556 (M + 1). Anal. (C36H33N3O3) C, H,
N.
2-[3-(ter t-Bu t yld ip h en ylsiloxym et h yl)-2,4-d im et h yl-
p h en yl]ben zon itr ile (25). To a solution of 24 (454 mg, 1.00
mmol) in dry THF (2.5 mL) was added dropwise 1.6 N
n-butyllithium in hexane (0.63 mL) in a dry ice-acetone bath
under nitrogen. After stirring for 1 h in a dry ice-acetone
bath, to this mixture was added dropwise a solution of zinc
chloride (141 mg, 1.03 mmol) in dry THF (1.4 mL) under dry
ice-acetone cooling. The bath was removed, and the reaction
mixture was stirred at ambient temperature for 1 h. This
mixture was added to a solution of 2-bromobenzonitrile (182
mg, 1.00 mmol) and tetrakis(triphenylphosphine)palladium-
(0) (23 mg, 0.020 mmol) in dry THF (1 mL) dropwise at
ambient temperature. The reaction mixture was then stirred
at this temperature for 20 h in the dark. The mixture was
diluted with AcOEt, washed with 1 N HCl, water, saturated
aqueous sodium bicarbonate solution, and brine, dried, and
evaporated in vacuo. The residue was purified by flash silica
gel column chromatography (hexane-AcOEt, 25:1) to give 25
(233 mg, 48.9%) as a colorless oil: 1H NMR (CDCl3) δ 1.06
(9H, s), 2.08 (3H, s), 2.28 (3H, s), 4.79 (2H, s), 7.04 (1H, d, J )
8 Hz), 7.08 (1H, d, J ) 8 Hz), 7.32-7.75 (14H, m); MS (ESI)
m/z 476 (M + 1). Anal. (C32H33NOSi) C, H, N.
Compounds 12b-d were prepared using a similar procedure
to that used for method A.
3-(2-Am in om eth ylth iop h en e-3-yl)-1-(ter t-bu tyld ip h en -
ylsiloxym eth yl)-2,6-d im eth ylben zen e (35). To a solution
of 34 (471 mg, 0.978 mmol) in dry THF (2 mL) was added 1 M
borane-THF complex (3 mL) under nitrogen at ambient
temperature and the reaction mixture was stirred for 14 h.
To the mixture was added 1 N HCl (1.5 mL) dropwise in an
ice-water bath, and the mixture stirred for 1 h at ambient
temperature. The mixture was partitioned between AcOEt
and water. The organic layer was washed with water and
brine, dried, and evaporated in vacuo. The residue was
purified by flash silica gel column chromatography (CHCl3-
MeOH, 50:1) to give 35 (67 mg, 62.7%) as a colorless oil: 1H
NMR (CDCl3) δ 1.05 (9H, s), 2.02 (3H, s), 2.27 (3H, s), 3.78
(2H, s), 4.76 (2H, s), 6.83 (1H, d, J ) 6 Hz), 7.00 (2H, br s),
7.20 (1H, d, J ) 6 Hz), 7.30-7.48 (6H, m), 7.63-7.75 (4H, m).
Anal. (C30H35NOSSi) C, H, N.
Compound 33 was prepared using a similar procedure to
that used for 25.
2-(3-H yd r oxym e t h yl-2,4-d im e t h ylp h e n yl)b e n zon i-
tr ile (26). To a solution of 25 (228 mg, 0.479 mmol) in THF
(2.5 mL) was added 1 M tetrabutylammonium fluoride in THF
(1.00 mL) at ambient temperature. After 1 h, the mixture was
partitioned between AcOEt and 1 N HCl. The organic layer
was washed with water and brine, dried, and evaporated in
vacuo. The residue was purified by flash silica gel column
chromatography (hexane-AcOEt, 4:1) to give 26 (72 mg,
63.3%) as a colorless oil: 1H NMR (CDCl3) δ 2.27 (3H, s), 2.50
(3H, s), 4.82 (2H, s), 7.07 (1H, d, J ) 8 Hz), 7.17 (1H, d, J )
8 Hz), 7.36 (1H, d, J ) 8 Hz), 7.45 (1H, t, J ) 8 Hz), 7.63 (1H,
t, J ) 8 Hz), 7.74 (1H, d, J ) 8 Hz). Anal. (C16H15NO) C, H,
N.
8-[[2,6-Dich lor o-3-(p yr r ol-1-yl)b e n zyl]oxy]-2-m e t h -
ylqu in olin e (39). A solution of 10a (3.33 g, 10.0 mmol) and
2,5-dimethoxytetrahydrofuran (1.32 g, 10.0 mmol) in AcOH
(8.3 mL) was heated at 100 °C for 2 h. To the reaction mixture
were added 2,5-dimethoxytetrahydrofuran (661 mg, 5.00 mmol)
and AcOH (8.3 mL) at ambient temperature, and the mixture
Compounds 32 and 37 were prepared using a similar
procedure to that used for 26.
3-(3-Am in oph en yl)-1-(ter t-bu tyldiph en ylsiloxym eth yl)-
2,6-d im eth ylben zen e (30). To a suspension of 3-aminophen-

4596 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23
Abe et al.
was heated at 100 °C for 2 h. The mixture was evaporated in
vacuo, and the residue was dissolved in CHCl3. The solution
was washed with saturated aqueous sodium bicarbonate
solution, water, and brine, dried, and evaporated in vacuo. The
residue was purified by flash silica gel chromatography
(hexane-CHCl3, 2:1) to give 39 (3.14 g, 81.9%) as a brown oil:
1H NMR (CDCl3) δ 2.75 (3H, s), 5.68 (2H, s), 6.33 (2H, d, J )
3 Hz), 6.87 (2H, d, J ) 3 Hz), 7.24-7.48 (6H, m), 8.02 (1H, d,
J ) 8 Hz). Anal. (C21H16Cl2N2O) C, H, N.
8-[[3-(2-Cya n op yr r ol-1-yl)-2,6-d ich lor ob en zyl]oxy]-2-
m eth ylqu in olin e (40). To a solution of 39 (1.00 g, 2.61 mmol)
in dry CH2Cl2 (10 mL) was added dropwise a solution of
chlorosulfonyl isocyanate (500 mg, 3.53 mmol) in dry CH2Cl2
(1 mL) in a dry ice-acetone bath below -20 °C under nitrogen.
The reaction mixture was stirred in a dry ice-acetone bath
for 30 min and then at ambient temperature for 1 h. The
mixture was cooled to -78 °C and treated with dry DMF (0.5
mL). The reaction mixture was stirred at the same temper-
ature for 30 min and at ambient temperature for 1 h. To the
mixture was added dropwise 4 N HCl (4 mL) in an ice-water
bath, and the mixture stirred for 30 min at that temperature.
To the mixture was added 4 N NaOH (8 mL) in an ice-water
bath, and the mixture was filtered through Celite. The filtrate
was extracted with CHCl3, washed with water and brine, dried,
and evaporated in vacuo. The residue was purified by flash
silica gel chromatography (hexane-CHCl3, 2:1) to give 40 (575
mg, 54.0%) as a colorless amorphous solid: 1H NMR (CDCl3)
δ 2.76 (3H, s), 5.69 (2H, s), 6.39 (1H, t, J ) 4 Hz), 6.95-7.02
(2H, m), 7.23-7.56 (6H, m), 8.03 (1H, d, J ) 8 Hz). Anal.
(C22H15Cl2N3O) C, H, N.
Compounds 14b-e, 23a ,b, 29a , 31, 36, 42, 43, 45, 48, and
49 were prepared using a similar procedure to that used for
method B.
8-[[3-[2-[(E)-3-(6-Ca r boxyp yr id in -3-yl)a cr yloyla m in o-
methyl]pyrrol-1-yl]-2,6-dichlorobenzyl]oxy]-2-methylquino-
lin e (46). A solution of 45 (100 mg, 0.162 mmol) in EtOH (1
mL) containing 1 N NaOH (0.3 mL) was heated at 60 °C for 1
h. Upon cooling, the reaction mixture was evaporated in vacuo
and dissolved with water. The water layer was washed with
ether, adjusted to pH 5 with 1 N HCl, and extracted with
CHCl3-MeOH (10:1, 4×). The organic layer was dried and
evaporated in vacuo. The residue was triturated with AcOEt
to give 46 (75 mg, 78.8%) as a colorless amorphous solid: 1H
NMR (DMSO-d6) δ 2.60 (3H, s), 4.15 (1H, m), 4.26 (1H, m),
5.43 (2H, s), 6.18-6.27 (2H, m), 6.80 (1H, d, J ) 16 Hz), 6.88
(1H, m), 7.27 (1H, d, J ) 8 Hz), 7.37-7.49 (3H, m), 7.53 (1H,
d, J ) 8 Hz), 7.62 (1H, d, J ) 8 Hz), 7.72 (1H, d, J ) 8 Hz),
8.02-8.14 (2H, m), 8.21 (1H, d, J ) 8 Hz), 8.41 (1H, br s),
8.85 (1H, d, J ) 2 Hz); MS (FAB) m/z 587 (M + 1). Anal.
(C31H24Cl2N4O4) C, H, N.
8-[[2,6-Dich lor o-3-[[(E)-3-[6-(N-m eth ylca r ba m oyl)p yr i-
d in -3-yl]a cr yloyla m in om eth yl]p yr r ol-1-yl]ben zyl]oxy]-2-
m eth ylqu in olin e (47). To a solution of 46 (100 mg, 0.170
mmol) in dry DMF (1 mL) were added methylamine hydro-
chloride (13 mg, 0.193 mmol), WSCD (32 mg, 0.206 mmol),
and HOBt (35 mg, 0.259 mmol) at ambient temperature. After
5 h, this mixture was partitioned between CHCl3 and satu-
rated aqueous sodium bicarbonate solution. The organic layer
was washed with water (4×) and brine, dried, and evaporated
in vacuo. The residue was purified by flash silica gel column
chromatography (CH2Cl2-MeOH, 40:1) to give 47 (86 mg,
84.3%) as a colorless amorphous solid: 1H NMR (CDCl3) δ 2.60
(3H, s), 3.00 (3H, d, J ) 6 Hz), 4.34 (1H, dd, J ) 15, 4 Hz),
4.52 (1H, dd, J ) 15, 4 Hz), 5.54 (1H, d, J ) 10 Hz), 5.61 (1H,
d, J ) 10 Hz), 6.28 (1H, m), 6.35 (1H, m), 6.47-6.61 (2H, m),
6.69 (1H, m), 7.18-7.31 (2H, m), 7.36-7.58 (6H, m), 7.78 (1H,
d, J ) 8 Hz), 7.86 (1H, m), 8.04 (1H, d, J ) 8 Hz), 8.39 (1H, br
s); MS (FAB) m/z 600 (M + 1). Anal. (C32H27Cl2N5O3) C, H,
N.
Meth od C. 8-[[3-[2-[(E)-3-(6-Aceta m id op yr id in -3-yl)-
a cr yloyla m in om et h yl]p yr r ol-1-yl]-2,6-d ich lor ob en zyl]-
oxy]-2-m eth ylqu in olin e Dih yd r och lor id e (52a ). To a
suspension of 44 (100 mg, 0.167 mmol) in MeOH (2 mL) was
added 10% hydrogen chloride in MeOH (2 mL) at ambient
temperature. To the mixture was added CHCl3 (0.5 mL), and
the mixture stirred for 10 min. The solution was evaporated
in vacuo and the residue washed with AcOEt to give 52a (106
mg, 94.3%) as a colorless amorphous solid: 1H NMR (DMSO-
d6) δ 2.11 (3H, s), 2.91 (3H, s), 4.17 (1H, m), 4.57 (1H, m), 5.56
(1H, d, J ) 10 Hz), 5.65 (1H, d, J ) 10 Hz), 6.19-6.27 (2H,
m), 6.51 (1H, d, J ) 15 Hz), 6.84 (1H, m), 7.27 (1H, d, J ) 15
Hz), 7.57 (1H, d, J ) 8 Hz), 7.67 (1H, d, J ) 8 Hz), 7.77-8.03
(5H, m), 8.09 (1H, d, J ) 8 Hz), 8.41 (1H, br s), 8.47 (1H, m),
9.03 (1H, m), 10.72 (1H, br s). Anal. (C32H27Cl2N5O3‚2HCl)
C, H, N.
8-[[3-(2-Am in om eth ylp yr r ol-1-yl)-2,6-d ich lor oben zyl]-
oxy]-2-m eth ylqu in olin e (41). To a suspension of lithium
aluminum hydride (168 mg, 4.43 mmol) in dry THF (25 mL)
was added a solution of 39 (1.51 g, 3.70 mmol) in dry THF (5
mL) dropwise in an ice-water bath under nitrogen. After 2
h, further lithium aluminum hydride (84 mg, 2.21 mmol) was
added thereto, and the reaction mixture was stirred at ambient
temperature for 1 h. To the mixture was added H2O (30 mL)
dropwise in an ice-water bath, followed by AcOEt. The
precipitate was removed by vacuum filtration through Celite,
which was then washed with AcOEt. The filtrate and wash-
ings were combined, and the organic layer was separated,
dried, and evaporated in vacuo. The residue was purified by
flash silica gel chromatography (CHCl3-MeOH, 50:1) to give
41 (797 mg, 52.2%) as a brown amorphous solid: 1H NMR
(CDCl3) δ 2.75 (3H, s), 3.55 (1H, d, J ) 16 Hz), 3.66 (1H, d, J
) 16 Hz), 5.70 (2H, s), 6.21 (1H, d, J ) 4 Hz), 6.28 (1H, t, J )
4 Hz), 6.64 (1H, d, J ) 4 Hz), 7.23-7.51 (6H, m), 8.02 (1H, d,
J ) 8 Hz). Anal. (C22H19Cl2N3O) C, H, N.
Compound 28 was prepared using a similar procedure to
that used for 41.
Meth od B. 8-[[3-[2-[(E)-3-(6-Aceta m id op yr id in -3-yl)-
a cr yloyla m in om et h yl]p yr r ol-1-yl]-2,6-d ich lor ob en zyl]-
oxy]-2-m eth ylqu in olin e (44). To a solution of 41 (100 mg,
0.243 mmol), (E)-3-(6-acetamidopyridin-3-yl)acrylic acid22 (58
mg, 0.279 mmol), and 1-hydroxybenzotriazole (HOBt; 49 mg,
0.364 mmol) in dry DMF (1 mL) was added WSCD‚HCl (56
mg, 0.291 mmol) in an ice-water bath under nitrogen. After
30 min, the reaction mixture was stirred at ambient temper-
ature for 2 h. The mixture was partitioned with CHCl3 and
saturated aqueous sodium bicarbonate solution. The organic
layer was washed with water (3×) and brine, dried, and
evaporated in vacuo. The residue was purified by flash silica
gel column chromatography (CHCl3-MeOH, 40:1) to give 44
(108 mg, 74.2%) as a colorless amorphous solid: 1H NMR
(CDCl3) δ 2.11 (3H, s), 2.59 (3H, s), 4.10 (1H, m), 4.24 (1H,
m), 5.42 (2H, d, J ) 3 Hz), 6.16-6.25 (2H, m), 6.57 (1H, d, J
) 15 Hz), 6.86 (1H, d, J ) 3 Hz), 7.25 (1H, d, J ) 8 Hz), 7.31
(1H, d, J ) 15 Hz), 7.36-7.47 (2H, m), 7.53 (1H, d, J ) 8 Hz),
7.63 (1H, d, J ) 8 Hz), 7.71 (1H, d, J ) 8 Hz), 7.95 (1H, m),
8.11 (1H, d, J ) 8 Hz), 8.17-8.30 (2H, m), 8.45 (1H, br s),
Compounds 50a , 51a , and 53a -55a were prepared using a
similar procedure to that used for method C.
Biologica l Meth od s. Recep tor Bin d in g: Gu in ea P ig
Ileu m . The specific binding of [3H]BK (a high-affinity B2
ligand) was assayed according to the method previously
described25 with minor modifications. Male Hartley guinea
pigs (from Charles River J apan, Inc.) were killed by exsan-
guination under anesthesia. The ilea were removed and
homogenized in ice-cold buffer (50 mM sodium (trimethylami-
no)ethanesulfonate (TES) and 1 mM 1,10-phenanthroline, pH
6.8) with a Polytron homogenizer. The homogenate was
centrifuged to remove cellular debris (1000g, 20 min, 4 °C),
and the supernatant was centrifuged (100000g, 60 min, 4 °C).
The pellet was then resuspended in ice-cold binding buffer I
(50 mM TES, 1 mM 1,10-phenanthroline, 140 µg/mL bacitra-
cin, 1 mM dithiothreitol, 1 µM captopril, and 0.1% bovine
serum albumin (BSA), pH 6.8) and was stored at -80 °C until
use.
10.66 (1H, br s); MS (ESI) m/z 600 (M + 1). Anal. (C32H27
Cl2N5O3) C, H, N.
-
In the binding assay, the membranes (0.2 mg of protein/

Orally Active Non-Peptide BK B2 Receptor Antagonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23 4597
mL) were incubated with 0.06 nM [3H]BK and varying
concentrations of test compounds or unlabeled BK at room
temperature for 60 min. Receptor-bound [3H]BK was har-
vested by filtration through Whatman GF/B glass fiber filters
under reduced pressure, and the filter was washed five times
with 300 µL of ice-cold buffer (50 mM Tris-HCl). The radio-
activity retained on the washed filter was measured with a
liquid scintillation counter. Specific binding was calculated
by subtracting the nonspecific binding (determined in the
presence of 1 µM unlabeled BK) from total binding. All
experiments were carried out three times.
Ack n ow led gm en t. We are grateful to Dr. D. Barrett
(Medicinal Chemistry Research Laboratories, Fujisawa
Pharmaceutical Co. Ltd., Osaka) for his valuable sug-
gestions.
Su p p or t in g In for m a t ion Ava ila b le: Physical data of
9b-d , 10b,d , 11b,c, 12b-d , 13c-e, 14b-e, 19, 22a ,b, 23a ,b,
27-29a , 31-33, 36-38, 42, 43, 45, 48-51a , and 53a -55a
(12 pages). Ordering information is found on any current
masthead page.
Refer en ces
Recom bin a n t Hu m a n B2 Recep tor s Exp r essed in CHO
cells. CHO (dhfr-) cells that were transferred with and stably
expressed human B2 receptors have been described previously.21b
Cells were maintained in an R-minimum essential medium
supplemented with penicillin (100 µg/mL), streptomycin (100
µg/mL), and 10% fetal bovine serum. The cells were seeded
in 48-well tissue culture plates at a density of 3.0 × 104 cells/
well and cultured for 1 day. The cells were washed three times
with phosphate-buffered saline containing 0.1% BSA and
incubated with 1.0 nM [3H]BK and test compounds for 2 h at
4 °C in 0.25 mL of binding buffer III (20 mM HEPES, 125
mM N-methyl-D-glucamine, 5.0 mM KCl, 1.8 mM CaCl2, 0.8
mM MgSO4, 0.05 mM bacitracin, 5 µM enalaprilat, and 0.1%
BSA, pH 7.2). All experiments were carried out three times.
Nonspecific binding was determined in the presence of 1 µM
unlabeled BK. At the end of the incubation, the buffer was
aspirated, and the cells were washed twice with ice-cooled
phosphate-buffered saline containing 0.1% BSA. The specific
binding was calculated by subtracting the nonspecific binding,
determined in the presence of 1 µM unlabeled BK, from the
total binding. Bound radioactivity was determined by solu-
bilizing with 1% sodium dodecyl sulfate containing 0.05 N
NaOH and quantitating in a liquid scintillation counter.
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- % responsedrug/% responsemean
of vehicle) × 100.
value
Sta tistica l An a lysis. Statistical significance was analyzed
with the results of percent inhibition between groups by
Student’s t-test. IC50 or ED50 value was obtained by using
nonlinear curve-fitting methods with a computer program
developed in-house.

4598 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 23
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