Substituted 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase

Article abstract of DOI:10.1021/jm960793t

A series of 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives have been synthesized and evaluated for their ability to selectively inhibit human heart chymase. The structureactivity relationship studies on these compounds gave the following results. The 1-phenyl moiety participates in a hydrophobic interaction where an optimum size is required. At this position, 3,4-dimethylphenyl is the best moiety for inhibiting chymase and showed high selectivity compared with chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrogen-bend acceptors such as nitrile and methoxycarbonyl enhances its activity. Molecular-modeling studies on the interaction of 3-[(4-chlorophenyl)sulfonyl]-1-(4-chlorophenyl)- imidazolidine-2,4-dione (29) with the active site of human heart chymase suggested that the 1-phenyl moiety interacts with the hydrophobic P₁ pocket, the 3-phenylsulfonyl moiety resides in the S₁-S₂ subsites, and the 4- carbonyl of the imidazolidine ring and sulfonyl group interact with the oxyanion hole and the His-45 side chain of chymase, respectively. The complex model is consistent with the structure-activity relationships.

Full text of DOI:10.1021/jm960793t

2156
J . Med. Chem. 1997, 40, 2156-2163
Su bstitu ted 3-(P h en ylsu lfon yl)-1-p h en ylim id a zolid in e-2,4-d ion e Der iva tives a s
Novel Non p ep tid e In h ibitor s of Hu m a n Hea r t Ch ym a se
Shinjiro Niwata,† Harukazu Fukami,*,† Motoo Sumida,† Akiko Ito,† Saki Kakutani,† Masayuki Saitoh,†
Kenji Suzuki,† Masahiro Imoto,† Hiroshi Shibata,† Seiichi Imajo,† Yoshinobu Kiso,† Takaharu Tanaka,†
Hiroshi Nakazato,† Takafumi Ishihara,† Shinji Takai,‡ Daisuke Yamamoto,§ Naotaka Shiota,‡ Mizuo Miyazaki,‡
Hideki Okunishi,| Akio Kinoshita, Hidenori Urata, and Kikuo Arakawa
Institute for Biomedical Research, Suntory Ltd., 1-1-1, Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka 618, J apan,
Department of Pharmacology and Medical Computation Center, Osaka Medical College, 2-7 Daigaku-cho,
Takatsuki 569, J apan, Department of Pharmacology, Shimane Medical University, 89-1 Enya-cho, Izumo,
Shimane 693, J apan, and Department of Internal Medicine, School of Medicine, Fukuoka University, 7-45-1, Nanakuma,
J onan-ku, Fukuoka 814-01, J apan
Received November 15, 1996X
A series of 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives have been synthesized
and evaluated for their ability to selectively inhibit human heart chymase. The structure-
activity relationship studies on these compounds gave the following results. The 1-phenyl
moiety participates in a hydrophobic interaction where an optimum size is required. At this
position, 3,4-dimethylphenyl is the best moiety for inhibiting chymase and showed high
selectivity compared with chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted
with hydrogen-bond acceptors such as nitrile and methoxycarbonyl enhances its activity.
Molecular-modeling studies on the interaction of 3-[(4-chlorophenyl)sulfonyl]-1-(4-chlorophenyl)-
imidazolidine-2,4-dione (29) with the active site of human heart chymase suggested that the
1-phenyl moiety interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides
in the S1′-S2′ subsites, and the 4-carbonyl of the imidazolidine ring and sulfonyl group interact
with the oxyanion hole and the His-45 side chain of chymase, respectively. The complex model
is consistent with the structure-activity relationships.
In tr od u ction
chymotrypsin-type serine proteases, we found that
compound 29 showed potent inhibitory activity for
chymase. We will describe here the structure-activity
relationships of 29 and its related compounds and the
fitting and interaction studies with a chymase model.
Angiotensin-I converting enzyme (ACE), a dipeptidyl
carboxylase, is a key enzyme in the formation of
angiotensin II (Ang II) from angiotensin I (Ang I).1
However, the conversion of Ang I to Ang II has been
demonstrated to occur in the presence of ACE inhibitors
in many tissues including the heart.2-5 The non-ACE
enzyme is inhibited by chymostatin, an inhibitor of
chymotrypsin-like enzymes.3,4,6,7 DNA analysis indi-
cates that this enzyme belongs to chymases.8 Chymase
converts Ang I to Ang II with greater efficiency and
selectivity than ACE.4,9 Although physiological and
pathological roles of this enzyme have not been fully
elucidated yet, increases in chymase activity and mRNA
level have been observed in balloon-injury induced
hypertrophied vessels in dogs10 and also in the heart of
cardiomyopathic hamsters.11 Thus, chymase may play
an important role in vascular hypertrophy and in
cardiovascular diseases such as hypertension, ischaemic
heart disease, and congestive heart failure.
Resu lts a n d Discu ssion
Most of compounds 1-15, 18-24, 27-29, 33-38, 40-
46, 48, and 50 were generally prepared by the reaction
of the corresponding arylsulfonyl isocyanates or benzoyl
isocyanate and N-aryl or heteroarylglycine or their ester
derivatives, followed by cyclization with ethyl chloro-
formate as shown in Scheme 1. The corresponding
arylsulfonyl isocyanates were obtained commercially or
by the reaction of sulfonamide with chlorosulfonyl
isocyanate.16 Substituted N-phenylglycine derivatives
were prepared by reductive alkylation of the corre-
sponding anilines and glyoxylic acid with NaBH3CN.
N-(3,4-Dimethylphenyl)glycine was obtained by N-alkyl-
ation of 3,4-dimethylacetoanilide with ethyl bromoac-
etate in the presence of NaH, followed by hydrolysis by
hydrochloric acid. p-Chlorobenzoyl derivative 47 was
prepared by the reaction of 1-phenylimidazolidine-2,4-
dione with p-chlorobenzoyl chloride in pyridine (Scheme
3-1). Carboxylic acid derivatives 16, 17, 30-32 were
obtained by treating the corresponding allyl esters with
Pd complex catalyst17 or treating the corresponding tert-
butyl esters with TFA (Scheme 2). Subsequently, the
corresponding carboxylic acid amides 25, 26, and 39
were prepared by the usual method (Scheme 2). 1-[(p-
Chlorophenyl)sulfonyl]imidazolidine-2,4-dione deriva-
tive 49 was obtained by cyclizing N-[(p-chlorophenyl)-
sulfonyl]glycine with p-chlorophenyl isocyanate (Scheme
3-2). 3-[(Benzoyloxy)methyl]imidazolidine-2,4-dione de-
Several synthetic inhibitors of chymase are known,
such as 2-(Z-NHCH2CONH)C6H4SO2F,12 methoxysuc-
cinyl-Ala-Ala-Pro-(L)boro-Phe-OH,13 Boc-Val-Pro-Phe-
CO2Me,14 Z-Ile-Glu-Pro-Phe-CO2Me, and (F)-Phe-CO-
Glu-Asp-ArgOMe.15 At present, however, no clinically
applicable chymase inhibitor has been found. In the
course of our study to provide nonpeptide inhibitors of
* Author to whom correspondence should be addressed.
† Suntory Ltd.
‡ Department of Pharmacology, Osaka Medical College.
§ Medical Computation Center, Osaka Medical College.
| Shimane Medical University.
Fukuoka University.
X Abstract published in Advance ACS Abstracts, J une 15, 1997.
S0022-2623(96)00793-5 CCC: $14.00 © 1997 American Chemical Society

Nonpeptide Inhibitors of Human Heart Chymase
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 14 2157
Sch em e 1a
a
(a) Substituted N-phenylacetic acid methyl ester; (b) 1 N NaOH; (c) substituted N-phenylacetic acid; (d) ethyl chloroformate/Et3N.
Sch em e 2
substitution gave IC50 values between 10-6 and 10-8 M.
The unsubstituted compound (1) was the least active
among them. Substituents such as chlorine (2-4),
fluorine (5), bromine (6), methoxy (9 and 10), nitro (13),
and phenoxy (20 and 21) increased the activity moder-
ately (IC50 ) ∼10-7 M). Methyl substitution did not
improve potency as much (IC50 ) 1.2-2.6 µM). On the
other hand, nitrile (11 and 12) and methoxycarbonyl
substitutions (14 and 15) remarkably increased potency
(IC50 ) ∼10-8 M). The following observations were
made regarding the effect of substitution patterns.
Ortho-substituted analogs tended to be less potent than
both meta- and para-substituted analogs. Meta- and
para-substituted analogs were approximately equipo-
tent except for the carboxylic acid (16 vs 17), (methoxy-
carbonyl)methyl (18 vs 19), and 4-methylpiperazinyl
amide (25 vs 26) analogs. Among these exceptions,
meta substitution was more effective than para substi-
tution. Meta,para-disubstituted compounds (22 and 23)
were some of the most active compounds. It is interest-
ing that 3,4-dimethyl derivative 23 gave excellent
activity despite the poor activity of 4-methyl derivative
8. These results show that the region binding phenyl-
sulfonyl moieties is rather hydrophobic and has enough
space to allow a phenoxyphenyl group (20 and 21). The
potent activity of nitrile (11 and 12) and methoxycar-
bonyl derivatives (14 and 15) may be the result of their
hydrogen-bond-accepting properties.
Sch em e 3
rivative 51 was prepared from 3-(bromomethyl)imida-
zolidine-2,4-dione derivative and benzoic acid under
basic conditions (Scheme 3-3).18
The compounds were tested in vitro for inhibition of
human heart chymase, bovine pancreas R-chymotrypsin,
and human neutrophil cathepsin G. The results are
given as IC50 values as shown in Tables 1-4.
First, we investigated the substituent effect of the
phenylsulfonyl moiety as shown in Table 1. This
Next, we examined the substitution on the 1-phenyl
moiety (Table 2). Generally, hydrophilic substituents

2158 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 14
Niwata et al.
Ta ble 1. Enzyme Inhibitory Activities of Substituted
Benzenesulfonyl Derivatives
Ta ble 3. Enzyme Inhibitory Activities of Tetrasubstituted
Derivatives
O
O
O
N
S
N
X
O
a
a
IC50
, µM
IC50
, µM
compd
X
Y
chymase chymotrypsin cathepsin G
compd
X
chymase chymotrypsin cathepsin G
40
41
42
43
3,4-Cl2
3,4-Me2 0.020
63
>100
>100
20
>100
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
H
2-Cl
3-Cl
4-Cl
4-F
4-Br
2-Me
4-Me
3-OMe
4-OMe
3-CN
4-CN
4-NO2
3-CO2Me
4-CO2Me
3-CO2H
4-CO2H
3-CH2CO2Me
4-CH2CO2Me
3-OPh
4-OPh
3,4-Cl2
6.2
1.1
1.4
1.2
>100
4.5
2.2
2.5
0.7
1.5
0.60
1.8
4.5
8.0
3,4-(OMe)2 3,4-Me2 0.022
3,4-Me2
3,4-Cl2
3,4-Me2 0.060
3,4-Cl2 0.17
1.7
2.3
0.13
0.38
0.37
0.17
1.8
3.7
1.1
2.6
2.4
1.1
7.0
3.7
5.8
0.73
a
Concentration inhibiting 50% of the corresponding enzyme.
Deviations of data are less than 10% of the mean. Conditions are
described in the Experimental Section.
2.6
0.58
0.55
0.068
0.040
0.70
0.082
0.029
0.86
5.9
and 32), N-acetylamino (35), and 4-methylpiperazinyl
amide (39) decreased the activity. The rather hindered
phenoxy derivative (34) also decreased the activity. The
highest activity observed for the 3,4-disubstituted de-
rivatives (36 and 37) was on the order of 10-8 M. These
data show that the 1-phenyl moiety is bound by hydro-
phobic interaction in a rather small space. This space
is most likely the P1 pocket in chymase.
From the above results, we examined the hybrid
tetrasubstituted derivatives 40-43 (Table 3). We found
compounds 40, 41, and 42 to be equipotent to or have
greater potency than the disubstituted analogs 22, 23,
24, and 29. However, tetrachloro derivative 43 was less
potent than 22 and 36. The 3,4-dimethylphenyl group
is presumably the most acceptable residue for the P1
pocket. Compounds 40 and 41 showed high specificity
for chymase although chymase, chymotrypsin, and
cathepsin G belong to the same family of serine pro-
teases.
4.2
0.78
0.33
6.5
0.64
0.34
1.0
1.9
5.4
6.5
3.3
15
8.0
1.7
1.8
8.5
44
4.0
11
1.4
8.0
3.8
2.0
0.50
5.0
0.80
0.70
0.018
0.030
0.11
0.90
3.7
0.23
0.22
4.1
3,4-Me2
3,4-(OMe)2
>100
1.4
4.8
3– Me
4– Me
N
N
N
N
O
O
26
3.3
6.4
16
a
Concentration inhibiting 50% of the corresponding enzyme.
Deviations of data are less than 10% of the mean. Conditions are
described in the Experimental Section.
Finally, we prepared other imidazolidindione deriva-
tives (Table 4). Instead of a 1-phenyl moiety, the
introduction of cyclohexyl (44), 2-pyridyl (45), and
2-pyrimidinyl group (46), respectively, decreased the
activity. Therefore, a benzene ring is optimal for the
P1 pocket. When the (4-chlorophenyl)sulfonyl group was
introduced at the 1-position of imidazolidine ring (49),
the activity disappeared. This might suggest that the
sulfonyl group in 49 could not interact with the hydro-
phobic P1 pocket. The activity of the amides 47 and 48
was substantially eliminated when compared to the
sulfonamide analogs. These compounds were potent
selective chymotrypsin inhibitors as illustrated by 48,
which had an IC50 of 10-8 M for chymotrypsin. This
result shows the difference between benzoyl and phen-
ylsulfonyl substitutions and suggests that the sulfonyl
group provides a specific interaction and conformational
bias for inhibition of chymase whereas amides cannot
achieve the same interaction but are selective for
chymotrypsin. The incorporation of a 1-benzylsulfonyl
group (50) in place of the 1-phenylsulfonyl substituent
eliminated the activity. The direction of the benzyl
group relative to the imidazolidine ring is different from
that of the phenyl group and creates steric hindrance
in the active site of the enzyme. This may be the reason
for the remarkable difference of activity between 50 and
1. 1-(Benzoyloxy)methyl derivative (51), which is used
in the case of elastase inhibitors,18 did not show any
activity. In the imidazolidine derivatives, the sulfonyl
moiety is essential for activity.
Ta ble 2. Enzyme Inhibitory Activities of Substituted Phenyl
Derivatives
O
O
O
N
Y
S
N
Cl
O
a
IC50
,
µM
compd
Y
chymase chymotrypsin cathepsin G
4
H
0.38
0.22
0.066
0.30
3.3
65
100
4.6
1.1
20
0.20
0.50
0.7
2.0
3.9
1.5
27 2-Cl
28 3-Cl
29 4-Cl
30 2-CO2H
31 3-CO2H
32 4-CO2H
33 2-OPh
34 4-OPh
35 4-NHAc
36 3,4-Cl2
37 3,4-Me2
73
26
>100
>100
5.9
4.8
>100
22
3.7
>100
>100
>100
42
37
39
28
>100
>100
0.023
0.035
14
27
4.0
43
>100
>100
38 3,4-OMe)2
39
4–
N
N
Me
O
a
Concentration inhibiting 50% of the corresponding enzyme.
Deviations of data are less than 10% of the mean. Conditions are
described in the Experimental Section.
were less potent than hydrophobic substituents. Hy-
drophilic substituents such as carboxylic acid (30, 31,

Nonpeptide Inhibitors of Human Heart Chymase
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 14 2159
Ta ble 4. Enzyme Inhibitory Activities of Other Derivatives
In this complex, the position of the 4-carbonyl and 3-N-
sulfonyl groups of the imidazolidine ring are fixed by
hydrogen bonds with the oxyanion hole and the His-45
side chain of chymase, respectively. The 1-(4-chloro-
phenyl) moiety is located in the P1 pocket. It seems that
directions and positions of the carbonyl and sulfonyl
groups relative to the phenyl moiety are fundamental
to the inhibition of chymase. The 3-[(4-chlorophenyl)-
sulfonyl] moiety was placed near the Arg-130 and Lys-
179 side chains in the S1′-S2′ subsites, capable of acting
as hydrogen-bond donors due to their positive charges.
We could explain the inhibitory data from the complex
model. The significant decrease of the inhibitory activ-
ity of compounds with bulky or hydrophilic groups at
the 1-phenyl moiety in Table 2 may be because these
substituents are unable to fit to the P1 pocket, making
the 4-carbonyl and 3-N-sulfonyl groups unable to inter-
act with the oxyanion hole and the His-45 side chain of
chymase, respectively. In the case of the carboxylic acid
substituent on the 1-phenyl moiety (30, 31, and 32), the
activity decreased in the order of ortho, meta, and para.
This result may suggest that the o-carboxylic acid stays
in front of the P1 pocket, thereby retaining activity. This
complex model was consistent with the inhibitory
increase by meta and/or para substitution of the 3-phen-
ylsulfonyl moiety with hydrogen-bond acceptors such as
methoxycarbonyl and nitrile. In the carboxylic acid (16
and 17) and (methoxycarbonyl)methyl (18 and 19)
analogs, the direction for an electrostatic or hydrogen-
bonding interaction may be important for the difference
in activity between meta and para positions. It was
made certain that the activity and specificity of these
inhibitors would be improved by the modification of
meta and/or para substitution in the benzenesulfonyl
moiety.
a
Concentration inhibiting 50% of the corresponding enzyme.
Deviations of data are less than 10% of the mean. Conditions are
described in the Experimental Section.
Fitting studies of compound 29 with human chymase
were performed based on the hypotheses that the
1-phenyl moiety of inhibitors interacts with the P1
pocket and the 4-carbonyl group of the imidazolidine
ring is located in the oxyanion hole in chymase to
interact with the catalytic serine residue. The latter
hypothesis was based on the chemical reaction of
compound 29 with sodium methoxide19 in methanol to
give N-[(4-chlorophenyl)sulfonyl]-N′-(4-chlorophenyl)-N′-
[(methoxycarbonyl)methyl]urea which was the ring-
opened product at the N3-C4 bond of the imidazolidine.
Thus, a stable complex of compound 29 with the active
site of chymase could be formed as shown in Figure 1.
In summary, we have reported that 1-phenylimida-
zolidine-2,4-dione derivatives are novel inhibitors en-
dowed with good potency and selectivity toward human
heart chymase.
F igu r e 1. Stereoview of the optimized conformation for human heart chymase and compound 29. Active triad (Ser-182, His-45,
Asp-89), the other residues of chymase and compound 29 are shown by orange, green, and yellow, respectively. 1-Phenyl,
imidazolidine, and 3-phenylsulfonyl moieties are placed near the P1 hole, oxyanion hole and Arg-130/Lys-179 of chymase,
respectively, and the 4-carbonyl and 3-N-sulfonyl of the imidazolidine are fixed by hydrogen bonds with the oxyanion hole and
His-45 side chain (2.70 and 3.04 Å), respectively.

2160 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 14
Niwata et al.
to extraction with AcOEt. The extract was washed with saline,
dried over Na2SO4, and then concentrated to dryness. The
residue was purified by silica gel chromatography (n-hexane/
AcOEt ) 3:1) and crystallized from n-hexane/AcOEt to give
the title compound (0.31 g) as white crystals: yield 9.2%; mp
157-157.5 °C; 1H-NMR (CDCl3) δ 4.32 (s, 2H), 7.0-8.2 (m,
14H). Anal. (C21H16N2O5S) C, H, N.
By the same manner, compound 3, 5, 6, 9-15, 18-20, 22-
24, 27, 28, 33-38, 40-46, and 50 were prepared. Their
physical data, yield, and analytical data were cited as follows.
3-[(3-Ch lor op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (3): white crystals; yield 21% (from (3-chlorophen-
yl)sulfonyl isocyanate); mp >250 °C; 1H-NMR (DMSO-d6) δ
4.52 (s, 2H), 7.1-8.1 (m, 9H). Anal. (C15H11ClN2O4S) C, H,
N.
Exp er im en ta l Section
Syn th esis. Melting points were measured by using a
Mettler FP-61 (automatic melting apparatus) and are uncor-
rected. 1H-NMR spectra were recorded on a J EOL FX-100,
J EOL EX-400, and Bruker ARX-400 using TMS as an internal
reference. Mass spectra were obtained on a J EOL J MX-AX500
by FAB ionization method. Elemental analyses were per-
formed on a Perkin-Elmer 240B elemental analyzer, and all
compounds submitted for testing had analytical results 0.4%
of the theoretical values.
Gen er a l Meth od 1 (Sch em e 1). 3-[(4-Ch lor op h en yl)-
su lfon yl]-1-(4-ch lor op h en yl)im id a zolid in e-2,4-d ion e (29).
To a solution of methyl [(4-chlorophenyl)amino]acetate (3 g,
15 mmol) in 40 mL of benzene was added (4-chlorophenyl)-
sulfonyl isocyanate (2.2 mL, 15 mmol), the mixture was stirred
for 1 h. Crystals formed were filtered to obtain N-[(4-
chlorophenyl)sulfonyl]-N′-(4-chlorophenyl)-N′-[(methoxycarbo-
nyl)methyl]urea (6.1 g, 100% yield).
The obtained urea derivative (2.6 g, 6.4 mmol) was dissolved
in a mixture of MeOH (25 mL) and 1 N NaOH (25 mL) and
then stirred for 5 h. The reaction mixture was acidified with
1 N HCl and then extracted with AcOEt. The resulting extract
was washed with water, dried over MgSO4, and then evapo-
rated to a residue, which was crystallized from n-hexane/
AcOEt to give N-[(4-chlorophenyl)sulfonyl]-N′-(4-chlorophenyl)-
N′-(carboxymethyl)urea (2.2 g, 88% yield).
3-[(4-F lu or op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (5): white crystals; yield 50% (from (4-fluorophen-
1
yl)sulfonyl isocyanate); mp 196.5-197 °C; H-NMR (DMSO-
d6) δ 4.51 (s, 2H), 7.1-8.2 (m, 9H). Anal. (C15H11FN2O4S) C,
H, N.
3-[(4-Br om op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (6): white crystals; yield 57% (from (4-bromophen-
1
yl)sulfonyl isocyanate); mp 190-191 °C; H-NMR (DMSO-d6)
δ 4.50 (s, 2H), 7.0-8.0 (m, 9H). Anal. (C15H11BrN2O4S) C, H,
N.
3-[(3-Meth oxyp h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (9): white crystals; yield 3.8% (from (3-methoxy-
phenyl)sulfonyl isocyanate); mp 201-201.5 °C; 1H-NMR (CDCl3)
δ 3.89 (s, 3H), 4.31 (s, 2H), 7.1-7.8 (m, 9H). Anal.
(C16H14N2O5S) C, H, N.
3-[(4-Meth oxyp h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (10): white crystals; yield 35% (from (4-methoxy-
phenyl)sulfonyl isocyanate); mp 210.5-211 °C; 1H-NMR (DMSO-
d6) δ 3.86 (s, 3H), 4.51 (s, 2H), 7.1-8.0 (m, 9H). Anal.
(C16H14N2O5S) C, H, N.
A mixture of the above urea (2.2 g, 5.5 mmol) and Et3N (2
mL, 15.5 mmol) in THF (50 mL) was cooled at 0 °C, and then
ethyl chloroformate (0.66 mL, 6.9 mmol) was added. After 1
h, the mixture was stirred for an additional 2 h at room
temperature. The resulting solution was extracted with
AcOEt, washed with saline, dried over MgSO4, and then
evaporated to dryness. The residue was crystallized from
n-hexane/AcOEt to obtain the title compound (1.3 g) as white
crystals: yield 59% (from urea); mp 239-240 °C; 1H-NMR
3-[(3-Cya n op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (11): white crystals; yield 26% (from (3-cyanophen-
(DMSO-d6) δ 4.49 (s, 2H), 7.4-8.1 (m, 8H). Anal. (C15H10
Cl2N2O4S) C, H, N.
-
1
yl)sulfonyl isocyanate); mp 194-195 °C; H NMR (DMSO-d6)
By the same manner, compound 1, 2, 4, 7, 8, and 48 were
prepared. Their physical data, yield, and analytical data were
cited as follows.
3-(P h en ylsu lfon yl)-1-p h en ylim id a zolid in e-2,4-d ion e
(1): white crystals; yield 37% (from urea); mp 212.5-214 °C;
1H-NMR (DMSO-d6) δ 4.53 (s, 2H), 7.1-8.1 (m, 10H). Anal.
(C15H12N2O4S) C, H, N.
3-[(2-Ch lor op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (2): white crystals; yield 28% (from (2-chlorophen-
yl)sulfonyl isocyanate); mp 217-220 °C; H-NMR (DMSO-d6)
δ 4.70 (s, 2H), 7.0-8.2 (m, 9H). Anal. (C15H11ClN2O4S) C, H,
N.
δ 4.52 (s, 2H), 7.1-8.5 (m, 9H). Anal. (C16H11N3O4S) C, H,
N.
3-[(4-Cya n op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (12): white crystals; yield 15% (from (4-cyanophen-
1
yl)sulfonyl isocyanate); mp 224-226 °C; H NMR (DMSO-d6)
δ 4.53 (s, 2H), 7.1-8.3 (m, 9H). Anal. (C16H11N3O4S) C, H,
N.
3-[(4-Nitr op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-2,4-
d ion e (13): white crystals; yield 12% (from (4-nitrophenyl)-
sulfonyl isocyanate); mp 203.5-204.5 °C; 1H-NMR (DMSO-
d6) δ 4.52 (s, 2H), 7.1-8.5 (m, 9H). Anal. (C15H11N3O6S), C,
H, N.
1
3-[(4-Ch lor op h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (4): white crystals; yield 81% (from urea); mp 188-
3-[[3-(Me t h oxyca r b on yl)p h e n yl]su lfon yl]-1-p h e n yl-
im id a zolid in e-2,4-d ion e (14): white crystals; yield 47%
(from [3-(methoxycarbonyl)phenyl]sulfonyl isocyanate); mp
1
192 °C; H-NMR (DMSO-d6) δ 4.27 (s, 2H), 7.2-8.2 (m, 9H).
Anal. (C15H11ClN2O4S) C, H, N.
1
170-171 °C; H-NMR (DMSO-d6) δ 3.92 (s, 3H), 4.51 (s, 2H),
1-P h en yl-3-(2-t olylsu lfon yl)im id a zolid in e-2,4-d ion e
(7): white crystals; yield 18% (from urea); mp 186-190 °C;
1H-NMR (DMSO-d6) δ 2.64 (s, 3H), 4.59 (s, 2H), 7.1-8.1 (m,
9H). Anal. (C16H14N2O4S) C, H, N.
1-P h en yl-3-(4-t olylsu lfon yl)im id a zolid in e-2,4-d ion e
(8): white crystals; yield 32% (from urea); mp 204-206 °C;
1H-NMR (DMSO-d6) δ 2.42 (s, 3H), 4.25 (s, 2H), 7.2-8.2 (m,
9H). Anal. (C16H14N2O4S) C, H, N.
7.1-8.4 (m, 8H), 9.28 (s, 1H). Anal. (C17H14N2O6S) C, H, N.
3-[[4-(Me t h oxyca r b on yl)p h e n yl]su lfon yl]-1-p h e n yl-
im id a zolid in e-2,4-d ion e (15): white crystals, yield 32%
(from [4-(methoxycarbonyl)phenyl]sulfonyl isocyanate); mp
1
186.5-187.5 °C; H-NMR (DMSO-d6) δ 3.90 (s, 3H), 4.52 (s,
2H), 7.1-7.6 (m, 5H), 8.1-8.3 (m, 4H). Anal. (C17H14N2O6S)
C, H, N.
3-[[3-[(Met h oxyca r b on yl)m et h yl]p h en yl]su lfon yl]-1-
p h en ylim id a zolid in e-2,4-d ion e (18): white crystals; yield
27% (from [3-[(methoxycarbonyl)methyl]phenyl]sulfonyl iso-
cyanate); mp 151.5-152 °C; 1H-NMR (DMSO-d6) δ 3.63 (s, 3H),
3.89 (s, 2H), 4.54 (s, 2H), 7.1-8.0 (m, 9H). Anal. (C18H16N2O6S)
C, H, N.
3-[[4-[(Met h oxyca r b on yl)m et h yl]p h en yl]su lfon yl]-1-
p h en ylim id a zolid in e-2,4-d ion e (19): white crystals, yield
33% (from [4-[(methoxycarbonyl)methyl]phenyl]sulfonyl iso-
cyanate); mp 204-206 °C; 1H-NMR (DMSO-d6) δ 3.62 (s, 3H),
3.86 (s, 2H), 4.53 (s, 2H), 7.1-8.1 (m, 9H). Anal. (C18H16N2O6S)
C, H, N.
3-Ben zoyl-1-p h en ylim id a zolid in e-2,4-d ion e (48): white
crystals; yield 76% (from urea); mp 188-192 °C; 1H-NMR
(DMSO-d6) δ 4.66 (s, 2H), 7.1-8.1 (m, 10H). Anal. (C16H12N2O3)
C, H, N.
Gen er a l m eth od 2 (Sch em e 1). 3-[(4-P h en oxyp h en yl)-
su lfon yl]-1-p h en ylim id a zolid in e-2,4-d ion e (21). To a so-
lution of (phenylamino)acetic acid (1.25 g, 8.29 mmol) in THF
(100 mL) was added (4-phenoxyphenyl)sulfonyl isocyanate (2.0
g, 8.29 mmol) at room temperature, and the mixture was
stirred for 16 h. After completion of the reaction, the mixture
was cooled to 0 °C and reacted with Et3N (2.09 g, 20.7 mmol)
and ethyl chloroformate (0.9 g, 8.29 mmol) followed by stirring
at 0 °C for 1 h. After the reaction, the resulting solution was
poured into 1 N HCl (40 mL) and saline (60 mL) and subjected
3-[(3-P h en oxyp h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (20): white crystals; yield 45% (from (3-phenoxy-

Nonpeptide Inhibitors of Human Heart Chymase
J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 14 2161
phenyl)sulfonyl isocyanate); mp 150-151 °C; 1H-NMR (DMSO-
d6) δ 4.52 (s, 2H), 7.1-7.8 (m, 14H). Anal. (C21H16N2O5S) C,
H, N.
(from (3,4-dichlorophenyl)sulfonyl isocyanate); mp 249-251 °C;
1H-NMR (DMSO-d6) δ 4.52 (s, 2H), 7.5-8.2 (m, 6H). Anal.
(C15H8Cl4N2O4S) C, H, N.
3-[(3,4-Dich lor oph en yl)su lfon yl]-1-ph en ylim idazolidin e-
2,4-d ion e (22): white crystals; yield 5.0% (from (3,4-dichlo-
rophenyl)sulfonyl isocyanate); mp 217-218 °C; 1H-NMR (DM-
SO-d6) δ 4.42 (s, 2H), 7.3-7.6 (m, 5H), 7.8-8.3 (m, 3H). Anal.
(C15H10Cl2N2O4S) C, H, N.
3-[(3,4-Dim et h ylp h en yl)su lfon yl]-1-p h en ylim id a zoli-
d in e-2,4-d ion e (23): white crystals; yield 50% (from (3,4-
dimethylphenyl)sulfonyl isocyanate); mp 227-228 °C; 1H-NMR
(DMSO-d6) δ 2.32 (s, 6H), 4.52 (s, 2H), 7.1-7.8 (m, 8H). Anal.
(C17H16N2O4S) C, H, N.
3-[(3,4-Dim eth oxyp h en yl)su lfon yl]-1-p h en ylim id a zoli-
d in e-2,4-d ion e (24): white crystals; yield 39% (from (3,4-
dimethoxyphenyl)sulfonyl isocyanate); mp 209-210 °C; 1H-
NMR (DMSO-d6) δ 3.83 (s, 3H), 3.87 (s, 3H), 4.51 (s, 2H), 7.1-
7.7 (m, 8H). Anal. (C17H16N2O6S) C, H, N.
3-[(4-Ch lor oph en yl)su lfon yl]-1-cycloh exylim idazolidin e-
2,4-d ion e (44): white crystals; yield 16% (from (4-chlorophen-
yl)sulfonyl isocyanate); mp 175-176 °C; H-NMR (DMSO-d6)
δ 1.0-2.0 (m, 10H), 3.72 (m, 1H), 4.20 (s, 2H), 7.89 (d, J ) 4.5
Hz, 2H), 8.14 (d, J ) 4.5 Hz, 2H). Anal. (C15H17ClN2O4S) C,
H, N.
1
3-[(4-Ch lor oph en yl)su lfon yl]-1-(2-pyr idyl)im idazolidin e-
2,4-d ion e (45): white crystals; yield 4.5% (from (4-chlorophen-
1
yl)sulfonyl isocyanate); mp 211-212 °C; H-NMR (DMSO-d6)
δ 4.53 (s, 2H), 7.25 (m, 1H), 7.8-8.2 (m, 6H), 8.43 (m, 1H).
Anal. (C14H10ClN3O4S) C, H, N.
3-[(4-Ch lor op h en yl)su lfon yl]-1-(2-p yr im id in yl)im id a -
zolid in e-2,4-d ion e (46): white crystals; yield 66% (from (4-
1
chlorophenyl)sulfonyl isocyanate); mp >250 °C dec; H-NMR
(DMSO-d6) δ 4.52 (s, 2H), 7.2-8.8 (m, 7H). Anal. (C13H9-
ClN4O4S) C, H, N.
3-[(4-Ch lor op h en yl)su lfon yl]-1-(2-ch lor op h en yl)im id a -
zolid in e-2,4-d ion e (27): white crystals; yield 25% (from (4-
3-[(P h en ylm eth yl)su lfon yl]-1-p h en ylim id a zolid in e-2,4-
d ion e (50): white crystals; yield 47% (from (phenylmethyl)-
sulfonyl isocyanate); mp 205-206 °C; 1H-NMR (DMSO-d6)
δ 4.56 (s, 2H), 4.97 (s, 2H), 7.1-7.7 (m, 10H). Anal.
(C16H14N2O4S) C, H, N.
1
chlorophenyl)sulfonyl isocyanate); mp 175-178 °C; H-NMR
(DMSO-d6) δ 4.32 (s, 2H), 7.2-8.2 (m, 8H). Anal. (C15H10
Cl2N2O4S) C, H, N.
-
3-[(4-Ch lor op h en yl)su lfon yl]-1-(3-ch lor op h en yl)im id a -
zolid in e-2,4-d ion e (28): white crystals; yield 2.1% (from (4-
chlorophenyl)sulfonyl isocyanate); mp >200 °C; 1H-NMR
Ca r boxylic Acid Der iva tives a n d th e Cor r esp on d in g
Am id e Der iva tives (Sch em e 2). 3-[(3-Ca r boxyp h en yl)-
su lfon yl]-1-p h en ylim id a zolid in e-2,4-d ion e (16). By the
general method 2, 3-[[3-[(allyloxy)carbonyl]phenyl]sulfonyl]-
1-phenylimidazolidine-2,4-dione was prepared from [3-[(allyl-
oxy)carbonyl]phenyl]sulfonyl isocyanate (56% yield).
In a 10% solution of formic acid in THF (10 mL) was
dissolved the above imidazolidine derivative (0.4 g, 1.0 mmol).
The resulting solution was deaerated under reduced pressure.
To the solution were added tetrakis(triphenylphosphine)-
palladium (50 mg, 0.04 mmol) and triphenylphosphine (50 mg,
0.2 mmol), followed by stirring at room temperature for 2 h
under shielding from the light. After completion of the
reaction, the mixture was concentrated to a residue, which was
crystallized from AcOEt to obtain the title compound (0.35 g)
(DMSO-d6) δ 4.32 (s, 2H), 7.1-8.2 (m, 8H). Anal. (C15H10
Cl2N2O4S) C, H, N.
-
3-[(4-Ch lor op h e n yl)su lfon yl]-1-(2-p h e n oxyp h e n yl)-
im id a zolid in e-2,4-d ion e (33): white crystals; yield 88%
(from (4-chlorophenyl)sulfonyl isocyanate); mp 180-181 °C;
1H-NMR (DMSO-d6) δ 4.32 (s, 2H), 6.8-8.0 (m, 13H). Anal.
(C21H15ClN2O5S) C, H, N.
3-[(4-Ch lor op h e n yl)su lfon yl]-1-(4-p h e n oxyp h e n yl)-
im id a zolid in e-2,4-d ion e (34): white crystals; yield 51%
(from (4-chlorophenyl)sulfonyl isocyanate); mp 179.5-181 °C;
1H-NMR (DMSO-d6) δ 4.50 (s, 2H), 6.9-8.1 (m, 13H). Anal.
(C21H15ClN2O5S) C, H, N.
1-[4-(Acetylam in o)ph en yl]-3-[(4-ch lor oph en yl)su lfon yl]-
im id a zolid in e-2,4-d ion e (35): white crystals; yield 23%
(from (4-chlorophenyl)sulfonyl isocyanate); mp 250-251 °C;
1H-NMR (DMSO-d6) δ 2.06 (s, 3H), 4.54 (s, 2H), 7.5-7.7 (m,
4H), 7.8-8.3 (m, 4H). Anal. (C17H14ClN3O5S) C, H, N.
3-[(4-Ch lor op h en yl)su lfon yl]-1-(3,4-d ich lor op h en yl)-
im id a zolid in e-2,4-d ion e (36): white crystals; yield 2.1%
as white crystals: yield 97%; mp 231-232 °C dec;
1H-NMR
(DMSO-d6) δ 4.50 (s, 2H), 7.1-8.4 (m, 8H), 8.54 (s, 1H), 13.68
(s, 1H). Anal. (C16H12N2O6S) C, H, N.
3-[(4-Ca r boxyp h en yl)su lfon yl]-1-p h en ylim id a zolid in e-
2,4-d ion e (17). By the general method 2, 3-[[4-[(allyloxy)-
carbonyl]phenyl]sulfonyl]-1-phenylimidazolidine-2,4-dione was
prepared from [4-[(allyloxy)carbonyl]phenyl]sulfonyl isocyan-
ate (76% yield). By the same manner of the preparation of
16, compound 17 (1.10 g) was obtained from the above
imidazolidine derivative (2.4 g, 5.62 mmol) as white crystals:
yield 54%; mp 230-233 °C dec; 1H-NMR (DMSO-d6) δ 4.52
(s, 2H), 7.1-8.2 (m, 9H), 13.61 (s, 1H). Anal. (C16H12N2O6S)
C, H, N.
3-[[3-[(4-Meth ylpiper azin yl)car bon yl]ph en yl]su lfon yl]-
1-p h en ylim id a zolid in e-2,4-d ion e (25). A suspension of 16
(200 mg, 0.56 mmol) in SOCl2 (1.0 mL) was warmed at 80 °C
for 2 h to form the corresponding acid chloride. The resulting
solution was evaporated under reduced pressure. The residue
was dissolved in THF (25 mL), and N-methylpiperazine (0.065
mL, 0.59 mmol) was added to the resulting solution under ice-
cooling, followed by stirring for 30 min. White crystals were
precipitated from the reaction solution and collected by filtra-
tion to give the title compound as the hydrochloride (0.14 g):
yield 53%; mp 151-153 °C; 1H-NMR (DMSO-d6) δ 2.76 (s, 3H),
2.8-3.8 (m, 8H), 4.52 (s, 2H), 7.1-8.2 (m, 9H), 11.1 (s, 1H).
Anal. (C21H22ClN4O5S‚HCl) C, H, N.
3-[[4-[(4-Meth ylpiper azin yl)car bon yl]ph en yl]su lfon yl]-
1-p h en ylim id a zolid in e-2,4-d ion e (26). In a similar manner
of obtaining 25, the title compound (0.23 g) was prepared as
the hydrochloride from 17 (0.20 g, 0.56 mmol): white crystals;
yield 87%; mp 212-214 °C; 1H-NMR (DMSO-d6) δ 2.75 (s, 3H),
2.9-3.8 (m, 8H), 4.53 (s, 2H), 7.1-8.2 (m, 9H), 11.14 (s, 1H).
Anal. (C21H22ClN4O5S‚HCl) C, H, N.
1-(4-Ca r boxyp h en yl)-3-[(4-ch lor op h en yl)su lfon yl]im i-
d a zolid in e-2,4-d ion e (32). By general method 2, 1-[4-(tert-
butyloxycarbonyl)phenyl]-3-[(4-chlorophenyl)sulfonyl]imida-
zolidine-2,4-dione was prepared from (4-chlorophenyl)sulfonyl
1
(from (4-chlorophenyl)sulfonyl isocyanate); mp >200 °C; H-
NMR (DMSO-d6) δ 4.31 (s, 2H), 7.3-8.2 (m, 7H). Anal.
(C15H9Cl3N2O4S) C, H, N.
3-[(4-Ch lor op h en yl)su lfon yl]-1-(3,4-d im et h ylp h en yl)-
im id a zolid in e-2,4-d ion e (37): white crystals; yield 11%
(from (4-chlorophenyl)sulfonyl isocyanate); mp 211-213 °C;
1H-NMR (DMSO-d6) δ 2.23 (s, 3H), 2.25 (s, 3H), 4.23 (s, 2H),
7.11-7.27 (m, 3H), 7.56 (d, 2H), 8.15 (d, 2H). Anal. (C17H15
ClN2O4S) C, H, N.
-
3-[(4-Ch lor op h en yl)su lfon yl]-1-(3,4-d im eth oxyp h en yl)-
im id a zolid in e-2,4-d ion e (38): white crystals; yield 45%
(from (4-chlorophenyl)sulfonyl isocyanate); mp 186-187 °C;
1H-NMR (DMSO-d6) δ 3.72 (s, 3H), 3.73 (s, 3H), 4.48 (s, 2H),
7.0-8.1 (m, 7H). Anal. (C17H15ClN2O6S) C, H, N.
3-[(3,4-Dich lor oph en yl)su lfon yl]-1-(3,4-dim eth ylph en yl)-
im id a zolid in e-2,4-d ion e (40): white crystals; yield 46%
(from (3,4-dichlorophenyl)sulfonyl isocyanate); mp 247-249 °C;
1H-NMR (DMSO-d6) δ 2.23 (s, 3H), 2.26 (s, 3H), 4.31 (s, 2H),
7.1-8.3 (m, 6H). Anal. (C17H14Cl2N2O4S) C, H, N.
3-[(3,4-Dim e t h oxyp h e n yl)su lfon yl]-1-(3,4-d im e t h yl-
p h en yl)im id a zolid in e-2,4-d ion e (41): white crystals; yield
33% (from (3,4-dimethoxyphenyl)sulfonyl isocyanate); mp
195-197 °C; 1H-NMR (CDCl3) δ 2.23 (s, 3H), 2.26 (s, 3H), 4.31
(s, 2H), 7.1-8.3 (m, 6H). Anal. (C19H20N2O6S) C, H, N.
3-[(3,4-Dim eth ylp h en yl)su lfon yl)-1-(3,4-d im eth ylp h en -
yl)im id a zolid in e-2,4-d ion e (42): white crystals; yield 18%
(from (3,4-dimethylphenyl)sulfonyl isocyanate); mp 165-166
°C; 1H-NMR (CD3OD) δ 2.22 (s, 3H), 2.25 (s, 3H), 4.25 (s, 2H),
7.1-8.0 (m, 6H). Anal. (C19H20N2O4S) C, H, N.
3[(3,4-Dich lor oph en yl)su lfon yl]-1-(3,4-dich lor oph en yl)-
im id a zolid in e-2,4-d ion e (43): white crystals; yield 11%

2162 J ournal of Medicinal Chemistry, 1997, Vol. 40, No. 14
Niwata et al.
isocyanate (38% yield). This compound (0.12 g, 0.27 mmol)
was dissolved in TFA (1.5 mL) and stirred for 10 min. The
resulting solution was evaporated under reduced pressure. The
residue was crystallized from Et2O to give the title compound
(90 mg) as white crystals: yield 85%; mp 271-272 °C; 1H-
NMR (DMSO-d6) δ 4.51 (s, 2H), 7.6-8.1 (m, 8H). Anal.
(C16H11ClN2O6S) C, H, N.
washed with water and Et2O successively to give the title
compound (91 mg) as white crystals: yield 87%; mp 171-173
1
°C; H-NMR (DMSO-d6) δ 4.41 (s, 2H), 5.89 (s, 2H), 7.1-8.1
(m, 10H). Anal. (C17H14N2O4) C, H, N.
P r otea se In h ibition Assa y. Human heart chymase was
purified according to the method of Urata et al.6 Human
leukocyte cathepsin G and bovine pancreas R-chymotrypsin
were purchased from Calbiochem Co., La J olla, CA, and Sigma
Chemical Co., St. Louis, MO, respectively.
1-(2-Ca r boxyp h en yl)-3-[(4-ch lor op h en yl)su lfon yl]im i-
d a zolid in e-2,4-d ion e (30). By general method 2, 1-[2-(tert-
butyloxycarbonyl)phenyl]-3-[(4-chlorophenyl)sulfonyl]imida-
zolidine-2,4-dione was prepared from (4-chlorophenyl)sulfonyl
isocyanate (6.8% yield). By the same manner of the prepara-
tion of 32, compound 30 (50 mg) was obtained from the above
imidazolidine derivative (60 mg, 0.13 mmol) as white crys-
The chymase activity regarding the ability to form Ang II
was assessed by using Ang I as a substrate according to the
procedure of Urata et al.20 with a minor modification. To
measure an inhibitory activity of the synthetic compounds on
human heart chymase, 0.1 unit of the purified enzyme was
preincubated with test compounds dissolved in DMSO at 37
°C for 10 min in 20 mM Tris HCl buffer (pH 7.5). The chymase
reaction was started by the addition of Ang I, and the reaction
was stopped with 30% acetic acid (final 15%) after 30 min
incubation. To determine the amount of Ang II formed, 10
µL of the aliquot was applied to a C18 reverse-phase HPLC
column (Develosil ODS 5, Nomura Chemical Co. Seto, J apan)
that was pre-equilibrated with water containing 0.05% TFA.
The column was developed using a 10-min linear acetonitrile
gradient (0-60%) at 2 mL/min. The IC50 value was calculated
from the inhibition of Ang II formation at different doses for
each compound. The inhibition experiments were repeated at
least three times with deviations of 10% from the mean. IC50
against human leukocyte cathepsin G was also determined
with the same procedure for chymase. In the case of bovine
pancreas chymotrypsin each compound was assayed at 37 °C
for 10 min in 20 mM Tris-HCl buffer (pH 7.5) containing 20
mM CaCl2. IC50 was determined with the same method as
chymase.
1
tals: yield 98%; mp 208-209 °C; H-NMR (DMSO-d6) δ 4.46
(s, 2H), 7.4-8.3 (m, 8H). Anal. (C16H11ClN2O6S) C, H, N.
1-(3-Ca r boxyp h en yl)-3-[(4-ch lor op h en yl)su lfon yl]im i-
d a zolid in e-2,4-d ion e (31). By general method 2, 1-[3-(tert-
butyloxycarbonyl)phenyl]-3-[(4-chlorophenyl)sulfonyl]imida-
zolidine-2,4-dione was prepared from (4-chlorophenyl)sulfonyl
isocyanate (9.7% yield). By the same manner of the prepara-
tion of 32, compound 31 (160 mg) was obtained from the above
imidazolidine derivative (250 mg, 0.55 mmol) as white crys-
1
tals: yield 75%; mp 254-255 °C; H-NMR (DMSO-d6) δ 4.54
(s, 2H), 7.5-8.3 (m, 8H). Anal. (C16H11ClN2O6S) C, H, N.
3-[(4-Ch lor op h en yl)su lfon yl]-1-[4-[(4-m eth ylp ip er a zi-
n yl)ca r bon yl]p h en yl]im id a zolid in e-2,4-d ion e (39). In a
manner similar to that of obtaining 25, the title compound
(0.18 g) was prepared as the hydrochloride from 32 (0.20 g,
1
0.51 mmol): white crystals; yield 38%; mp 172-175 °C; H-
NMR (DMSO-d6) δ 2.76 (s, 3H), 3.4-3.6 (m, 8H), 4.55 (s, 2H),
7.6-8.1 (m, 8H). Anal. (C21H21ClN4O5S‚HCl) C, H, N.
3-(4-Ch lor ob e n zoyl)-1-p h e n ylim id a zolid in e -2,4-d i-
on e (47) (Sch em e 3-1). To a solution of 1-phenylimidazoli-
dine-2,4-dione (0.5 g, 2.84 mmol) in pyridine (20 mL) was
added p-chlorobenzoyl chloride (0.5 g, 2.86 mmol) at 0-5 °C,
and then the mixture was stirred at the same temperature
for 2 h. After the reaction, 1 N HCl was added to the solution,
and then the precipitate formed was filtered and recrystallized
from n-hexane/AcOEt to obtain the title compound (0.22 g) as
white crystals: yield 25%; mp 182-183.5 °C; 1H-NMR (DMSO-
d6) δ 4.63 (s, 2H), 7.1-8.1 (m, 9H). Anal. (C16H11ClN2O3) C,
H, N.
Mod elin g of Hu m a n Hea r t Ch ym a se. The homology
alignment of amino acid sequences of human heart chymase
and rat mast cell protease II (RMCP II)21 indicated that the
two sequences were 62% identical (conservation of 139 out of
226 residues), and neither insertion nor deletion was found.
According to the homology alignment, the preliminary three-
dimensional structure model of human heart chymase was
constructed by substitution of 85 amino acid residues onto the
atomic coordinates of RMCP II structure22 deposited in the
Protein Data Bank (accession number is 3RP2). The initial
structure was applied to conjugate gradient minimization and
10 ps molecular dynamics simulation in a Monte Carlo water
generated in 10.0 Å around the enzyme molecules. The
alignment and graphical operations were performed with a
QUANTA/CHARMM system,23 and the structural optimization
was calculated using the implemented parameters for protein
molecules.23-25
1-[(4-Ch lor op h en yl)su lfon yl]-3-(4-ch lor op h en yl)im id a -
zolid in e-2,4-d ion e (49) (Sch em e 3-2). To a mixture of N-[(p-
chlorophenyl)sulfonyl]glycine ethyl ester (2.78 g, 10 mmol),
triethylenediamine (60 mg, 0.5 mmol), and chlorobenzene (20
mL) was added p-chlorophenyl isocyanate (3.08g, 20 mmol),
and the mixture was refluxed for 2 h. After the reaction,
AcOEt was added, and the mixture was washed with water
and then dried over Na2SO4, followed by evaporation to a
residue, which was chromatographed on silica gel (CHCl3). The
fraction of the product was concentrated and crystallized from
n-hexane/AcOEt to obtain the title compound (2.98 g) as white
crystals: yield 77%; mp 193-194 °C; 1H-NMR (CDCl3) δ 4.56
(s, 2H), 7.3-8.3 (m, 8H). Anal. (C15H10Cl2N2O4S) C, H, N.
3-[(Ben zoyloxy)m eth yl]-1-p h en ylim id a zolid in e-2,4-d i-
on e (51) (Sch em e 3-3). A mixture of 1-phenylimidazolidine-
2,4-dione (556 mg, 3.16 mmol), 37% formalin (5.0 mL, 66.7
mmol), and MeOH (20 mL) was stirred at 70 °C for 2 h. After
the reaction, water (20 mL) was added and the precipitate was
filtered and washed with water to give 3-(hydroxymethyl)-1-
phenylimidazolidine-2,4-dione (585 mg, 90% yield). This
compound (103 mg, 0.5 mmol) was suspended in DMF (2 mL)
and then cooled with ice. PBr3 (19 µL, 0.2 mmol) was added
to the resulting suspension, and the mixture was stirred for 1
h. More PBr3 (10 µL) was added, and the mixture was stirred
for 15 min. To the resulting solution was added water (20 mL),
and the formed precipitate was collected and washed with
water to obtain 3-(bromomethyl)-1-phenylimidazolidine-2,4-
dione (116 mg, 86% yield).
Mod elin g of P u ta tive Com p lex of Hu m a n Hea r t Ch y-
m a se a n d Com p ou n d 29 (F igu r e 1). The structure of
compound 29 was generated and optimized by MM2 force field
implemented in a QUANTA/CHARMM system. In order to
estimate the position of the phenyl ring of the inhibition in P1
pocket of human heart chymase, the γ-chymotrypsin structure
(stored in the PDB entry 1GCT), which contains the tetrapep-
tide Pro-Gly-Ala-Tyr26 bound to active site of the protease, was
used. The tetrapeptide was transformed onto the human heart
chymase active site by the transformation that superimposes
16 R-carbons of chymotrypsin onto human heart chymase with
an RMS error of 0.33 Å, because the backbones of chymases
and chymotrypsin are nearly identical in the vicinity of the
primary specificity pocket (P1 hole) and the active site catalytic
triad. In the first step of the structural optimization, the
inhibitor 29 was docked into the active site of human heart
chymase using the CHARMM program to match the 1-phenyl
and 4-carbonyl of the imidazolidine ring with the phenyl and
carbonyl of the tetrapeptide tyrosine, respectively. The initial
structure was applied to conjugate gradient minimization and
10 ps molecular dynamics simulation in a Monte Carlo water
generated in 10.0 Å around the enzyme molecules using the
parameters23-25 implemented in a QUANTA/CHARMM sys-
tem.23
To a solution of benzoic acid (54 mg, 0.44 mmol) and
diisopropylethylamine (70 µL, 0.40 mmol) in DMF (1 mL) was
added the bromo derivative (100 mg, 0.37 mmol), the mixture
was stirred at room temperature for 20 min, and then cold
water was added. The resulting precipitate was filtered and

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