Synthesis and antimuscarinic activity of a series of 4-(1-Imidazolyl)-2,2-diphenylbutyramides: Discovery of potent and subtype-selective antimuscarinic agents

Article abstract of DOI:10.1016/S0968-0896(99)00003-6

In a study directed toward the development of new, selective agents with potential utility in the treatment of altered smooth muscle contractility and tone, for example, as seen in urinary incontinence associated with bladder muscle instability, a series of 4-(1-imidazolyl)-2,2-diphenylbutyramide derivatives was prepared. These compounds were examined for M₁, M₂, and M₃ muscarinic receptor subtype selectivity in isolated tissue assays. The compounds that showed potency and/or selectivity in these tests were further evaluated for in vivo anticholinergic effects on various organs and tissues, including urinary bladder, salivary gland, and eye in rats. The structure-activity relationships for the series of 4-(1-imidazolyl)-2,2-diphenylbutyramide derivatives are also discussed. This study led to the identification of 4-(2-methyl-1-imidazolyl)-2,2-diphenylbutyramide (KRP-197) as a candidate drug for the treatment of urinary bladder dysfunction. Copyright (C) 1999 Elsevier Science Ltd.

Full text of DOI:10.1016/S0968-0896(99)00003-6

Bioorganic & Medicinal Chemistry 7 (1999) 1151±1161
Synthesis and Antimuscarinic Activity of a Series of
4-(1-Imidazolyl)-2,2-diphenylbutyramides: Discovery of Potent
and Subtype-selective Antimuscarinic Agents
Hiroyuki Miyachi,* Hiromi Kiyota, Hideharu Uchiki and Mitsuru Segawa
Central Research Laboratories, Kyorin Pharmaceutical Co., Ltd., 2399-1 Mitarai, Nogi-machi, Shimotsuga-gun,
Tochigi 329-0114, Japan
Received 30 October 1998; accepted 22 December 1998
AbstractÐIn a study directed toward the development of new, selective agents with potential utility in the treatment of altered
smooth muscle contractility and tone, for example, as seen in urinary incontinence associated with bladder muscle instability, a
series of 4-(1-imidazolyl)-2,2-diphenylbutyramide derivatives was prepared. These compounds were examined for M1, M2, and M3
muscarinic receptor subtype selectivity in isolated tissue assays. The compounds that showed potency and/or selectivity in these
tests were further evaluated for in vivo anticholinergic e€ects on various organs and tissues, including urinary bladder, salivary
gland, and eye in rats. The structure±activity relationships for the series of 4-(1-imidazolyl)-2,2-diphenylbutyramide derivatives are
also discussed. This study led to the identi®cation of 4-(2-methyl-1-imidazolyl)-2,2-diphenylbutyramide (KRP-197) as a candidate
drug for the treatment of urinary bladder dysfunction. # 1999 Elsevier Science Ltd. All rights reserved.
Introduction
three pharmacologically distinct receptor subtypes (M1±
M3).9 The M1 receptor is found at high density in neu-
ronal tissues,10 whereas M2 and M3 receptors are mainly
present in peripheral e€ector organs, such as heart (M2)
and smooth muscle (M3).11 On the other hand, a mole-
cular cloning study indicated that muscarinic acetyl-
choline receptors are composed of at least ®ve
molecularly distinct receptor proteins (m1±m5).12 The
pharmacologically de®ned M1±M3 receptors are thought
to correspond to the cloned m1±m3 subtypes.
Recently, there has been much interest in the treatment
of urinary dysfunction, such as urinary incontinence,
owing to the rapid increase in the proportion of aged
people in the population. Urinary incontinence is a
pathological condition frequently a€ecting the elderly;
epidemiological investigations indicate that 5±15% of
the adult population are a€ected and the prevalence,
particularly of urge incontinence, increases with age.
The symptoms of an unstable bladder comprise urge
incontinence, urgency, and frequency. Bladder instabil-
ity is considered to be caused by uncontrolled detrusor
contractions,1 which are believed to be mediated by
muscarinic acetylcholine receptors.2 Consequently,
muscarinic acetylcholine receptor antagonists, such as
oxybutynin HCl and propiverine HCl (Fig. 1), have
for years been the drugs of choice for the treatment of
urinary incontinence associated with bladder muscle
instability. But the use of these compounds is limited by
their anticholinergic side e€ects, which include dry
mouth, accommodation paralysis, and tachycardia.5
In situ hybridization13 and immunoprecipitation14 stu-
dies on the human urinary bladder have revealed the
presence of M2 and M3 receptor subtypes. In spite of
the predominant presence of the M2 receptor in the
bladder, the muscarinic receptor(s) responsible for the
contraction of the bladder is the M3 subtype.15 There-
fore, M3-selective antagonists could have therapeutic
potential for the treatment of diseases associated with
altered smooth muscle contractility and tone, such as
urinary incontinence.
3
4
.
.
In our continuing research directed toward the devel-
opment of M3-selective muscarinic antagonists, using
the 3,3-diphenylpropylamine-type anticholinergic agent
Muscarinic acetylcholine receptors, members of the
huge superfamily of G protein-coupled receptors,6±8 are
heterogeneous, and have been classi®ed into at least
16
.
terodiline HCl (Fig. 1) as a lead compound, we found
that incorporation of an imidazole ring as a surrogate of
aliphatic amine generated M3-selectivity, and introduc-
tion of a carbamoyl group at the diphenylmethyl moiety
enhanced the anticholinergic potency.17 On the basis of
Key words: Antagonists; anticholinergics; molecular modelling/
mechanics; receptors.
*Corresponding author.
0968-0896/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(99)00003-6

1152
H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
.
Figure 1. Structures of anticholinergic agents, oxybutynin HCl, propiverine HCl, and terodiline HCl.
.
.
these observations, a series of 4-(1-imidazolyl)-2,2-di-
phenylbutyramides, as well as related quaternary salts,
was prepared in order to obtain anticholinergic agents
with greater potency and M3-selectivity. These com-
pounds were tested for functional muscarinic receptor
subtype selectivity in rabbit vas deferens (neuronal,
M1),18 guinea pig atrial (cardiac, M2),19 and guinea pig
ileal (smooth muscle, M3) preparations.20 To evaluate
the potential to cause side e€ects, selected compounds
were also examined for in vivo anticholinergic e€ects
in rats. The results of these studies, which led to the
identi®cation of 4-(2-methyl-1-imidazolyl)-2,2-diphenyl-
butyramide (KRP-197) as a candidate for the clinical
treatment of bladder dysfunction,21 are described in this
article.
(31, 32), respectively. The hydroxymethyl derivative (30)
was prepared by the reduction of 28 with sodium bis(2-
methoxyethoxy)aluminum hydride.24 The hydroxyl
derivative (27) was prepared by the reaction of ethyl (2-
methyl-1-imidazolyl)propionate25 with phenyllithium.
Imidazole derivatives (2±5) were treated with an excess
of alkyl or benzyl halide to give the imidazolium halides
(33±40).26 Physical data for the present series of imida-
zole and imidazolium derivatives are summarized in
Table 1.
Results and Discussion
The imidazole derivatives and imidazolium derivatives
synthesized in this study were examined for anti-
muscarinic activity in tests selective for the pharmaco-
logically de®ned muscarinic receptors. M1 receptor
antagonistic activity was determined as the ability to
reverse the inhibitory activity of the selective M1 agonist
McN-A-34327 on electrically stimulated contraction of
isolated rabbit vas deferens.18 M2 receptor antagonistic
activity was determined as the ability to decrease the
activity of acetylcholine to inhibit the contraction of
isolated guinea pig right atria.28 M3 receptor antag-
onistic activity was determined as the activity of the test
compound to decrease the response of guinea pig ileum
muscle strips to acetylcholine.3,26 In each test, potency
was de®ned as an anity constant (Kb),29 i.e. the cal-
culated molar concentration of the test compound that
causes a twofold increase in the EC50 values of the
muscarinic agonists used in the functional tests. The
compounds that exhibited potent and/or selective anti-
muscarinic activity were further evaluated in vivo. The
e€ects were expressed as ED30 and ED50 values (dose
required to reduce each in vivo e€ect by 30% and 50%,
respectively). The pharmacological results for the com-
pounds prepared are listed in Tables 2±9.
Chemistry
The synthetic routes to the imidazole derivatives descri-
bed in this study are outlined in Chart 1. Substituted
phenylacetonitriles were alkylated with the appropriate
dihalogenoalkane,22 followed by reaction with the
appropriate imidazole, to form the cyanoalkylimid-
azoles. The cyano group was hydrolyzed with either
sulfuric acid, or hydrochloric acid to give the carbamoyl
derivatives (1±23) and the carboxylic acid derivative
(29), respectively (in the case of 24 and 25, alkaline
hydrolysis23 was performed to obtain carboxamide
derivatives, since hydrolysis with sulfuric acid a€orded
only hydroxyl derivatives). The carboxylic acid deriva-
tive (29) was treated with thionyl chloride, then with
either methanol or the appropriate amines to give the
methyl ester derivative (28) and the amide derivatives
As already mentioned, we synthesized 3,3-diphenylpro-
pylamine derivatives and evaluated their antimuscarinic
activity and subtype-selectivity.17 We found that the
incorporation of an imidazole ring as a surrogate of
aliphatic amine a€orded equipotent antimuscarinic
activity as compared to that of aliphatic amine deriva-
tives, with M3-selectivity. We also found that introduc-
tion of a carbamoyl group as a benzylic substituent
enhanced the antimuscarinic activity. These results
prompted us to synthesize 4-(imidazol-1-yl)-2,2-diphenyl-
butyramide (1) and we found that it showed potent
Figure 2. Structure of compound (1).

H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
1153
Chart 1. Schematic procedure for the synthesis of the present series of imidazole derivatives. Reagents: (a) phenylacetonitrile derivative,22 imidazole
derivative, Et3N, N,N-dimethylformamide; (b) aq H2SO4 or ethanolic KOH; (c) c.HCl; (d) SOCl2, methanol or amines; (e) ester derivative, sodium
bis (2-methoxyethoxy)aluminium hydride, benzene; (f) ethyl (2-methyl-1-imidazolyl)propionate,25 phenyl lithium, THF; (g) alkyl iodide or benzyl
bromide, acetone.
antimuscarinic activity, comparable to that of oxybutynin,
with M3-selectivity (10-fold M3-selectivity). Therefore, we
selected 1 as the lead compound to explore M3-selective
antimuscarinic agents. Compound 1 is composed of
four active regions of importance, (1) the imidazole
moiety, (2) the linker moiety, (3) the benzylic substituent
moiety, and (4) the diphenylmethyl moiety, so chemical
modi®cation of each part of the molecule was performed
to obtain detailed structure±activity relationships.
results prompted us to speculate that both the width
and the length of the substituents introduced at the
imidazole ring play a critical role in binding to the
receptors, and the shape of the cavity of the anionic site
cavity is di€erent in each muscarinic receptor subtype.
E€ect of the linker moiety
As can be seen from Table 3, the maximum anti-
muscarinic activity was obtained when the spacer was
the ethylene chain, for both M2- and M3-subtypes, and
elongation of the spacer decreased the activity. These
data indicate that the distance between the cationic head
(imidazole moiety) and lipophilic tail (diphenylaceta-
mide moiety) of these molecules is important for potent
antimuscarinic activity. Introduction of a methyl group
into the ethylene chain decreased the activity, probably
due to the consequent change of the relative orientation
of the cationic head moiety and the lipophilic tail moi-
ety. It might also be that the methyl group interfered
with the proper ligand±receptor interaction. All the
compounds, except 14, listed in Table 3 exhibited about
10-fold or greater selectivity for M3 over M2, so the
length of the spacer methylene chain and the side chain
methyl group are not critical for subtype-selectivity.
E€ect of the imidazole moiety
As indicated in Table 2, introduction of appropriate
alkyl groups at the imidazole ring strikingly a€ected the
antimuscarinic activity and subtype-selectivity. Intro-
duction of a methyl group into position 2 or 5 of the
imidazole ring increased both anti-M3 and anti-M2
activities, but the 4-methyl group did not appear to
a€ect the activity. These results indicated that the
substituent located near the N-1 imidazole nitrogen
favorably interacted with an anionic cavity of these
receptor-subtypes. On the other hand, introduction of
bulkier substituents generally decreased the anti-
muscarinic activity; for example, the 2-n-propylimida-
zole derivative (4) exhibited about 500- and 60-fold less
potent anti-M3 and anti-M2 activities as compared to
those of the 2-methyl derivative (2), and it showed no
marked M3-selectivity. In contrast, the 4,5-di-n-propyl-
imidazole derivative (9) retained M3-selectivity, although
it exhibited decreased antimuscarinic activity. These
E€ect of the diphenylmethyl moiety
Table 4 illustrates the importance of the steric factor at
the lipophilic tail part of the molecule. The presence of

1154
H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
Table 1. Physicochemical properties of the imidazole derivatives
Analysis (%)
Calcd
H
Found
H
No.
mp (ꢀC)
Mass (m/z)
Formula
C
N
C
N
.
C19H19N3O 0.6H2O
1
2
3
4
5
6
7
8
172.0±175.0
189.0±190.0
144.0±146.0
150.0±152.0
166.0±168.0
136.0±138.0
163.0±164.5
194.0±196.0
147.0±148.0
151.0±153.0
173.0±175.0
197.0±199.0
128.0±129.0
154.0±156.0
159.0±161.0
165.0±167.0
148.0±150.0
206.0±207.5
163.0±165.0
173.0±175.0
191.0±192.5
178.0±180.0
212.0±214.0
218.0±220.0
193.0±194.5
157.0±158.5
212.0±2.14.0 (dec.)
84.0±86.0
305 (M+
319 (M+
334 (M+
347 (M+
347 (M+
361 (M+
333 (M+
361 (M+
389 (M+
319 (M+
319 (M+
355 (M+
333 (M+
347 (M+
361 (M+
333 (M+
333 (M+
355 (M+
349 (M+
257 (M+
285 (M+
325 (M+
320 (M+
345 (M+
333 (M+
301 (M+
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
72.17 6.44 13.29
75.21 6.63 13.16
75.65 6.95 12.60
76.05 7.25 12.09
75.66 7.27 12.03
74.56 7.62 11.34
75.65 6.95 12.60
76.42 7.53 11.62
76.38 8.05 10.69
75.21 6.63 13.16
75.21 6.63 13.16
75.80 6.08 11.53
74.84 7.00 12.47
76.05 7.25 12.09
76.42 7.53 11.62
74.04 7.04 12.34
75.65 6.95 12.60
67.59 5.39 11.82
72.18 6.63 12.03
70.01 7.44 16.33
71.10 8.14 14.63
73.40 8.38 12.84
70.43 6.35 17.29
76.49 6.71 12.16
72.05 5.74 12.60
67.50 6.23 11.81
72.20 6.32 12.89
74.98 6.80 13.00
75.42 7.08 12.43
75.98 7.25 12.03
75.67 7.30 12.04
74.60 7.46 11.10
75.37 7.05 12.43
76.25 7.64 11.48
76.28 7.79 10.69
75.32 6.79 13.07
75.07 6.64 12.89
75.90 5.95 11.27
74.63 7.03 12.31
75.96 7.22 11.93
76.29 7.53 11.55
74.09 7.49 11.56
75.48 7.16 12.50
67.23 5.55 11.63
72.03 6.66 11.87
69.73 7.47 16.14
71.15 8.11 14.43
73.25 8.46 12.71
70.59 6.38 17.25
76.44 6.76 12.09
72.01 5.95 12.63
67.55 6.21 11.99
C20H21N3O
C21H23N3O
C22H25N3O
.
C22H25N3O 0.1H2O
.
C23H27N3O 0.5H2O
C21H23N3O
C23H27N3O
.
C25H31N3O 0.2H2O
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
C20H21N3O
C20H21N3O
.
C23H21N3O 0.5H2O
.
C21H23N3O 0.2H2O
C22H25N3O
C23H27N3O
.
C21H23N3O 0.4H2O
C21H23N3O
C20H19F2N3O
C21H23N3O2
C15H19N3O
.
C17H23N3O 0.1H2O
.
C20H27N3O 0.1H2O
.
C19H20N4O 0.2H2O
C22H23N3O
C20H19N3O2
.
C20H19N3 HCl H2O
.
292(M+
334 (M+
320 (M+
306 (M+
333 (M+
347 (M+
)
C19H20N2O 0.1H2O
77.57 6.92
75.02 6.66
67.32 5.93
78.40 7.24
9.52
8.33
7.85
9.14
77.66 6.87
75.00 6.80
67.22 5.97
78.41 7.41
9.24
8.36
7.81
9.09
.
.
C21H22N2O2 0.1H2O
)
)
)
)
)
.
C20H20N2O2 HCl
237 (dec.)
155.0±156.5
153.0±154.5
Oil
C20H22N2O
.
C21H23N3O 0.1H2O
.
75.24 6.98 12.54
74.50 7.33 11.85
75.17 7.11 12.53
74.25 7.52 11.91
C22H25N3O 0.4H2O
.
C21H24IN3O 0.2H2O
234.0±236.0
189.0±192.0
173.0±175.0
164.0±166.0
230.0±232.0
229.0±230.5
215.0±216.0
238.0±239.0
334 (M 127)+
348 (M 127)+
362 (M 127)+
376 (M 127)+
410 (M 80)+
348 (M 127)+
362 (M 127)+
362 (M 127)+
54.25 5.29
54.35 5.64
56.04 5.81
57.26 6.01
66.12 5.75
55.59 5.51
56.45 5.77
56.45 5.77
9.04
8.64
8.52
8.35
8.57
8.84
8.59
8.59
54.02 5.30
54.54 5.78
55.89 5.68
57.08 5.94
66.41 5.86
55.32 5.51
56.69 5.83
56.35 5.64
9.00
8.34
8.51
8.23
8.68
8.94
8.89
8.73
.
C22H26IN3O 0.6H2O
.
C23H28IN3O 0.2H2O
C24H30IN3O
C27H28BrN3O
C22H26IN3O
C23H28IN3O
C23H28IN3O
an unsubstituted diphenylmethyl group as a lipophilic
substituent resulted in the most potent anticholinergic
activity. The replacement of one phenyl group with an
alkyl group (20, 21 and 22) or a 2-pyridyl group (23)
also decreased the activity. The inactivity of 20 and 21
might be due to decreased hydrophobic interaction with
a lipophilic cavity. Decreased activity of 22 might indi-
cate the importance of ꢀ±ꢀ interaction between the
lipophilic tail moiety and receptor cavity hosting the
diphenylmethyl group. Introduction of substituents at
one or both benzene rings (19, 18) decreased the activ-
ity. These results might indicate that the hydrophobic
cavity hosting the diphenylmethyl group is not deep and
substituents introduced at the para position interacted
unfavorably with the cavity. The ®xation of the two
phenyl groups with an ethylene chain (24) or an ether
bond (25) also resulted in a marked decrease in activity.
These data indicate that the relative orientation of the
two phenyl rings plays a critical role in the ligand-
receptor interaction. We speculate that the presence
of two phenyl groups located orthogonally at the
lipophilic tail part of the molecule is essential for potent
antimuscarinic activity. Interestingly, modi®cation of
the diphenylmethyl group decreased the antimuscarinic
activity, but did not reduce the M3 selectivity.
E€ect of the benzylic substituent moiety
As shown in Table 5, the compounds bearing only the
N,N-unsubstituted carbamoyl group (2) and the car-
boxyl group (29) exhibited potent antimuscarinic activ-
ity and M3 selectivity, and the compounds possessing
other functional groups lost the selectivity for the M3
receptor (26, 27 and 30) or showed markedly decreased
M2 and M3 antagonist activity. It is of interest to note
that the compounds bearing the N-monosubstituted and
N,N-disubstituted carbamoyl groups and the ester
group (31, 32 and 28, respectively) exhibited little or no
antimuscarinic activity. These results suggest that
hydrogen-bonding interactions may be important for
potent antimuscarinic activity and M3 selectivity. These
benzylic substituents may occupy a hydrophobic cavity,

H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
1155
Table 2. Antimuscarinic activity of imidazole derivatives in guinea pig atria (M2 receptor) and ileum (M3 receptor)
Kb (nM)
a
b
No.
R
M3
M2
M1
M2/M3
M1/M3
1
2
3
4
5
6
7
8
H
2-Me
2-Et
2-n-Pr
2-i-Pr
2-t-Bu
4,5-diMe
4,5-diEt
5.07
0.317
78.1
177
1.80
30.2
68.4
5.99
0.552
N.T.c
N.T.
30.9
N.T.
N.T.
N.T.
N.T.
10.4
13.5
13.0
3.30
1.44
15.8
2.45
3.21
22.7
25.2
3.10
11.1
3.07
1.76
1.45
1.18
1.74
Ð
Ð
17.7
Ð
Ð
Ð
Ð
1.03
3.94
Ð
Ð
0.712
4.13
258
254
28.5
73.9
8.66
90.5
2520
31.3
9.59
6540
119
5.00
2.70
3.98
9
4,5-di-n-Pr
4-Me
5-Me
100
10.1
0.862
2130
67.7
3.44
10
11
12
3.40
R0=1-benzimidazolyl
N.T.
N.T.
2.45
.
Terodiline HCl
.
Oxybutynin HCl
aThe selectivity ratio is the di€erence between the Kb values at M2 (atrium) and M3 (ilium) muscarinic receptors.
bThe selectivity ratio is the di€erence between the Kb values at M1 (vas deferens) and M3 (ilium) muscarinic receptors.
cNot tested.
Table 3. Antimuscarinic activity of imidazole derivatives in guinea
pig atria (M2 receptor) and ileum (M3 receptor)
These structure±activity relationship studies indicated
that the structure of 4-(1-imidazolyl)-2,2-diphenyl-
butyamide derivatives can be divided into two regions
from the viewpoint of biological activity. One region,
composed of the spacer methylene moiety and the
diphenylmethyl moiety, is involved in the manifestation
of antimuscarinic activity, and the other region, com-
posed of the carbamoyl moiety and the imidazole moiety,
contributes to both antimuscarinic activity and subtype-
selectivity. A molecular modeling study of compound
(2)30 revealed that one of the carbamoyl hydrogens faces
the imidazole moiety, probably due to a hydrogen
bonding interaction between carbamoyl hydrogen and
proximal imidazole nitrogen (Fig. 3). Therefore, the
carbamoyl group and the imidazole moiety of 2 are
located close to each other. These data indicate that the
interaction of the cationic head moiety of ligands
(including the imidazole moiety and carbamoyl moiety)
with the anionic site cavity of muscarinic receptor-sub-
types is critical for subtype selectivity.
Kb (nM)
a
No.
X
M3
M2
M2/M3
2
(CH2)2
(CH2)3
(CH2)4
0.317
1.14
43.7
71.3
2.89
16.9
4.13
20.1
148
710
45.1
174
13.0
17.6
3.39
9.96
15.6
10.3
13
14
15
16
17
(CH2)5
CHCH3CH2
CH2CHCH3
b
b
aSee footnote a in Table 1.
bAssayed as a racemate.
E€ect of quaternization
As can be seen from Table 6, alkyl quaternization of
compound 2 (33±37) did not a€ect the anti-M2 activity,
while it considerably decreased the anti-M3 activity.
Therefore, alkyl quaternization derivatives of compound
2 showed equipotent anti-M2 and anti-M3 activity and
decreased subtype-selectivity. In contrast, alkyl qua-
ternization of compounds 3 and 4 (38±40) considerably
increased both the anti-M3 and anti-M2 activity. This
or more probably, ®ll a part of the cavity occupied by
the two phenyl rings. So, it appears that the N,N-
unsubstituted carbamoyl group allows optimal occupa-
tion of the hydrophobic cavity, and that further
increasing the size of the substituent (31, 32 and 28)
leads to a decrease in activity for both M2 and M3
receptor-subtypes.

1156
H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
Table 4. In vitro functional activity of imidazole derivatives at M2
receptors in guinea pig atria and M3 receptors in guinea pig ileum
Table 6. Antimuscarinic activity of imidazolium salt derivatives in
guinea pig atria (M2-receptor) and ileum (M3-receptor)
Kb (nM)
Kb (nM)
a
a
R1
R2
X
M3
M2
M2/M3
No.
A
B
M3
M2
M2/M3
No.
2
Ph
4-FPh
Ph
Ph
Ph
Ph
4-FPh
0.317
9.85
24.6
1830
394
19.0
2.86
4.13
161
744
N.T.
N.T.
603
50.1
N.T.
N.T.
13.0
16.3
30.2
Ð
33
34
35
36
37
38
39
40
2
CH3
CH3
CH3
CH3
CH3
C2H5
(CH2)2CH3
(CH2)3CH3
CH2C6H5
CH3
I
I
I
I
3.78
7.11
4.07
3.12
6.34
9.24
12.3
18.2
66.8
4.68
21.8
6.35
4.13
1.68
1.30
3.02
5.83
13.5
4.11
1.74
3.50
13.0
18
19
20
21
22
23
24
25
4-MeOPhc
Mec
i-Prc
Cyclohexylc
2-Pyridylc
Ð
CH3
C2H5
(CH2)2CH3
CH(CH3)2
CH3
Br 4.96
I
I
I
Ð
Ph
Ph
31.7
17.5
Ð
1.14
12.5
1.82
CH3
CH3
Ð
Dibenzosuberan-5-yl
Xanthen-9-yl
2140
>1000
Ð
0.317
aSee footnote a in Table 1.
bNot tested.
cAssayed as a racemate.
aSee footnote a in Table 1.
.
Table 7. The inhibitory e€ects of KRP-197 and oxybutynin HCl on
the isovolumetric bladder contraction and the decreased bladder
capacity elicited by carbachol in conscious rats
Table 5. In vitro functional activity of imidazole derivatives at M2
receptors in guinea pig atria and M3 receptors in guinea pig ileum
Drugs
Isovolumetric
bladder contraction
(ED30, mg/kg, id)a
Decreased
bladder capacity
(ED50, mg/kg, ig)b
KRP-197
Oxybutynin HCl
0.11 (0.058±0.20)c
2.1 (1.2±3.5)c
0.074 (0.021±0.17)c
1.1 (0.78±1.6)c
.
aid, Intraduodenal administration.
big, Intragastric administration.
cFigures in parentheses are 95% con®dence limits.
resulted in unfavorable interacton with the muscarinic
receptor M3-subtype and decreased anti-M3 activity.
Kb (nM)
a
No.
R
M3
M2
4.13
15.5
50.1
N.T.b
82.7
83.8
5870
478
M2/M3
Compounds that possessed potent and/or subtype-
selective antagonism were further evaluated for anti-M1
activity.18 As can be seen from Table 2, here again, the
shape and position of the substituents at the imidazole
ring strikingly a€ect the subtype-selectivity. The unsub-
stituted and 2-methyl-substituted imidazole derivatives
(1 and 2, respectively) exhibited equipotent anti-M1 and
anti-M3 activities, but the 2-isopropyl- and 5-methyl-
substituted derivatives (5 and 11, respectively) showed
about 18- and fourfold less potent anti-M1 activity as
compared to anti-M3 activity. These data support our
hypothesis that the three-dimensional interactions
between the cationic head moiety of the imidazolylbu-
tyramide derivatives and anionic sites of functional
muscarinic acetylcholine receptor subtypes play a cri-
tical role in subtype-selectivity.
2
CONH2
CN
OH
CO2Me
CO2H
CH2OH
CONHMe
CON(Me)2
0.317
10.4
16.7
13.0
1.49
3.00
Ð
11.9
3.30
1.14
1.85
26
27
28
29
30
31
32
>1000
6.95
25.4
5150
258
aSee footnote a in Table 1.
bNot tested.
discrepancy is interesting but the reasons remain
unknown. The benzyl quaternary salt 37 was unique in
that it was much more e€ective at the M3 receptor and
less potent at the M2 receptor, though overall it showed
less potent activity. Contrary to the results obtained in
the imidazole series, in the case of imidazolium salts, a
molecular modeling study indicated that carbonyl oxygen
faces the imidazolium group due to electrostatic inter-
action between carbonyl oxygen and the imidazolium
cation (Fig. 3). This conformational change might have
On the basis of their potency as M3 muscarinic receptor
antagonists and/or their pharmacological subtype selec-
tivity, 4-(2-methyl-1-imidazolyl)-2,2-diphenylbutyramide
(2: KRP-197) was further studied in vivo. These results

H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
Table 8. The in¯uence of KRP-197 on the muscarinic-mediated
1157
responses in the heart, gut, urinary bladder, salivary gland, and eye in
the rats
ED50 (mg/kg)
Organs
Rat
Urinary bladder
Gut
Heart
Salivary gland
Eye (pupil diameter)
0.11 (0.058±0.20)a,d,e
0.39 (0.11±1.0)a,c,e
1.0 (0.72±1.5)a,e
1.1 (0.75±1.6)b,e
1.8 (1.2±3.1)a,e
aIntraduodenal administration.
bPer os.
cED100 value (dose to prolong contraction interval by 100%).
dED30 value (dose to prolong contraction interval by 30%).
eFigures in parentheses are 95% con®dence limits.
.
Table 9. The relative selectivity of KRP-197 and oxybutynin HCl for
the urinary bladder compared with the salivary gland
Drugs
Carbachol-induced
Salivary secretion Ratio
detrusor hyperre¯exia (ED50, mg/kg, p.o.)c of
(ED50, mg/kg, i.g.)b
ED50Sa
KRP-197
0.074 (0.021±0.17)d
1.1 (0.75±1.6)d
3.6 (1.9±6.4)d
15
3.3
Oxybutynin HCl 1.1 (0.78±1.6)d
.
aRatio of salivary secretion/carbachol-induced detrusor hyperre¯exia.
big, Intragastric administration.
cPer os.
dFigures in parentheses are 95% con®dence limits.
are given in Tables 7±9 (although compound 5 exhibited
M3 selectivity, a preliminary in vivo study indicated that
its in vivo action on urinary bladder contraction was
weak and the duration of action was short, probably
due to rapid metabolism, so further in vivo study was
not performed).
Figure 3. Energy minimized structure of 2 (KRP-197; top) and its
methyl quaternary salt 33 (bottom).
rats. The muscarinic-mediated responses in heart, gut,
urinary bladder, salivary gland and eye, causing vagal-
induced bradycardia,33 spontaneous ileal contraction,31
isovolumetric bladder contraction,31 carbachol-induced
salivary secretion34 and tonic contraction of the iris
sphincter (pupil diameter),35 respectively, were inhibited
in a dose-dependent manner. As shown in Table 8, the
rank order of the e€ective dose in rats was as follows:
urinary bladder>gut>heart and salivary gland>eye
(pupil size). KRP-197 exhibited selectivity for the blad-
der over the other organs tested in rats.
Muscarinic-mediated bladder contraction (isovolumetric
bladder contraction) and decreased bladder capacity
(carbachol-induced detrusor hyperre¯exia), models of
pollakiuria31 and urinary incontinence,32 were examined
in conscious rats. Intraduodenal administration of
KRP-197 (0.04±0.30mg/kg) inhibited bladder contraction
dose-dependently, and the ED30 value was 0.11mg/kg.
The inhibitory action of KRP-197 on the bladder con-
traction was 19 times as potent as that of oxybutynin
(Table 7), and the duration of action was similar to that
of oxybutynin (data not shown). In another model of
pollakiuria, KRP-197 showed preventive action against
the decrease in bladder capacity induced by carbachol
(ED50 0.074 mg/kg, intragastric administration), and
the potency of the inhibitory action was 15-fold greater
than that of oxybutynin (Table 7). In both models of
micturition dysfunction, KRP-197 was e€ective at the
dose range of 0.020±0.20 mg/kg (intraduodenal or
intragastric administration), being 15±19 times more
potent than oxybutynin. Furthermore, the relatively
potent activities in these rat models in vivo appeared to
re¯ect those in the functional studies in vitro.
Further, in order to assess the relative selectivity of
KRP-197 and oxybutynin for the muscarinic receptors
in the bladder, the ED50 value for the inhibition of sal-
ivation was expressed as a ratio with respect to the ED50
value for the inhibition of bladder contraction. It can
be seen from Table 9 that KRP-197 is more selective
(®vefold more) for the bladder than is oxybutynin.
These in vitro and in vivo studies suggest that 4-(2-
methyl-1-imidazolyl)-2,2-diphenylbutyramide (2; KRP-
197) is a potent, muscarinic M1- and M3-selective
antagonist, and shows selectivity for the bladder over
the heart and the salivary gland in vitro and in vivo.
Thus, KRP-197 could have therapeutic potential for the
The in¯uence of KRP-197 on the muscarinic-mediated
responses in various organs or tissues was studied in

1158
H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
treatment of symptoms in diseases associated with
altered smooth muscle contractility and tone with a
lower incidence of side e€ects. Clinical studies of KRP-
197 are in progress.
4-(2-Ethyl-1-imidazolyl)-2,2-diphenylbutyramide (3). High
MS (EI+) m/z calcd for C21H23N3O 333.1841, found
333.1847; 1H NMR (400 MHz, CDCl3) d 1.22±1.25 (3H,
t, J=7.3 Hz), 2.50±2.55 (2H, q, J=7.3 Hz), 2.70±2.74
(2H, m), 3.77±3.81 (2H, m), 5.36 (1H, s), 5.75 (1H, s),
6.73 (1H, d, J=1.5 Hz), 6.89 (1H, d, J=1.0 Hz), 7.32±
7.42 (10H, m).
Experimental
General
4-(2-n-Propyl-1-imidazolyl)-2,2-diphenylbutyramide (4).
High MS (EI+) m/z calcd for C22H25N3O 347.1998,
1
Melting points were determined on a Yanagimoto micro
1
Found 347.2014; H NMR (400 MHz, CDCl3) d 0.89±
melting point apparatus and are uncorrected. H NMR
0.93 (3H, t, J=7.3 Hz), 1.60±1.70 (2H, m), 2.46 (2H, t,
J=7.8 Hz), 2.70±2.74 (2H, m), 3.78±3.82 (2H, m), 5.34
(1H, s), 5.57 (1H, s), 6.74 (1H, d, J=1.4 Hz), 6.89 (1H,
d, J=1.0 Hz), 7.32±7.42 (10H, m).
spectra were measured in CDCl3 or DMSO-d6 with
TMS and the solvent peak as internal standards, on a
JEOL JMN-A400 spectrometer. Mass spectra (MS)
were obtained on a JEOL JMS-HX110 spectrometer.
Column chromatography was carried out on Merck
silica gel 60. Analytical thin-layer chromatography
(TLC) was performed on Merck precoated silica gel
60F254 plates, and the compounds were visualized by
UV illumination (254 nm) or by heating to 150 ꢀC after
spraying with phosphomolybdic acid in ethanol. Ele-
mental analysis was performed in the microanalytical
laboratory of Kyorin Pharmaceutical Co., Ltd.
4-(2-i-Propyl-1-imidazolyl)-2,2-diphenylbutyramide (5).
High MS (EI+) m/z calcd for C22H25N3O 347.1998,
1
Found 347.1991; H NMR (400 MHz, CDCl3) d 1.21±
1.22 (6H, d, J=6.8 Hz), 2.72±2.76 (2H, m), 2.79±2.84
(1H, m), 3.80±3.84 (2H, m), 5.36 (1H, s), 5.75 (1H, s),
6.71 (1H, s), 6.90 (1H, s), 7.32±7.42 (10H, m).
4-(2-t-Butyl-1-imidazolyl)-2,2-diphenylbutyramide (6).
High MS (EI+) m/z calcd for C23H27N3O 361.2154,
1
Found 361.2193; H NMR (400 MHz, CDCl3) d 1.26
Chemistry
(9H, s), 2.79±2.84 (2H, m), 3.94±3.99 (2H, m), 5.36 (1H,
s), 5.63 (1H, s), 6.83 (1H, s), 6.87 (1H, s), 7.34±7.43
(10H, m).
4-(2-Methyl-1-imidazolyl)-2,2-diphenylbutyramide (2). A
mixture of 4-bromo-2,2-diphenylbutyronitrile (3.00 g,
10.0 mmol), 2-methylimidazole (2.46 g, 30.0 mmol), tri-
ethylamine (1.40 mL, 13.5 mmol), and N,N-dimethyl-
formamide (50 mL) was stirred at 150 ꢀC for 30 h. The
mixture was poured into water, and extracted with
benzene, and the extract was washed, dried (Na2SO4),
and concentrated. The residue was puri®ed by silica gel
column chromatography, eluting with CH2Cl2:ethanol
(10:1 v/v), and treated with ethanolic HCl to give 4-(2-
methyl-1-imidazolyl)-2,2-diphenylbutyronitrile (2.60 g,
77%). Then, the cyano compound (7.83 g, 26.0 mmol)
was mixed with 70% sulfuric acid (50 mL) and stirred at
140±150 ꢀC for 40 min. The mixture was carefully basi-
®ed, and extracted with CHCl3, then the extract was
washed with brine, dried (Na2SO4), and concentrated.
The residue was recrystallized from a mixed solvent of
ethyl acetate:ethanol to give 4-(2-methyl-1-imidazolyl)-
2,2-diphenylbutyramide (2.02 g, 24%) as a colorless
needle: mp 189.0±190.0 ꢀC (from ethyl acetate:ethanol);
High MS (EI+) m/z calcd for C20H21N3O 319.1685,
found 319.1671; 1H NMR (400 MHz, CDCl3) d 2.23
(3H, s), 2.69±2.74 (2H, m), 3.77±3.82 (2H, m), 5.33 (1H,
s), 5.49 (1H, s), 6.73 (1H, s), 6.85 (1H, s), 7.31±7.42
(10H, m).
4-(4,5-Dimethyl-1-imidazolyl)-2,2-diphenylbutyramide (7).
High MS (EI+) m/z calcd for C21H23N3O 333.1841,
1
Found 333.1820; H NMR (400 MHz, CDCl3) d 2.05
(3H, s), 2.11 (3H, s), 2.67±2.71 (2H, m), 3.73±3.77 (2H,
m), 5.36 (1H, s), 5.70 (1H, s), 7.18 (1H, s), 7.31±7.41
(10H, m).
4-(4,5-Diethyl-1-imidazolyl)-2,2-diphenylbutyramide (8).
High MS (EI+) m/z calcd for C23H27N3O 361.2154,
1
Found 361.2178; H NMR (400 MHz, CDCl3) d 0.99
(3H, t, J=7.6 Hz), 1.19 (3H, t, J=7.6 Hz), 2.42 (2H, q,
J=7.6 Hz), 2.47 ( 2H, q, J=7.6 Hz), 2.71±2.75 (2H, m),
3.74±3.78 (2H, m), 5.34 (1H, br s), 5.58 (1H, br s), 7.21
(1H, s), 7.32±7.41 (10H, m).
4-(4,5-Di-n-propyl-1-imidazolyl)-2,2-diphenylbutyramide
(9). High MS (EI+) m/z calcd for C25H31N3O 389.2467,
1
Found 389.2453; H NMR (400 MHz, CDCl3) d 0.83
(3H, t, J=7.3 Hz), 0.92 (3H, t, J=7.3 Hz), 1.32 (2H,
hept, J=7.3 Hz), 1.64 ( 2H, hept, J=7.3 Hz), 2.34 (2H, t,
J=7.3 Hz), 2.43 (2H, t, J=7.3 Hz), 2.72±2.76 (2H, m),
3.77±3.81 (2H, m), 5.41 (1H, br s), 5.74 (1H, br s), 7.32±
7.42 (10H, m), 7.46 (1H, s).
A similar procedure was employed for the preparation
of compounds 1±23. The yields (two steps) were about
5±70%. The high resolution mass spectra and the NMR
data are as follows.
4-(4-Methyl-1-imidazolyl)-2,2-diphenylbutyramide (10).
High MS (EI+) m/z calcd for C20H21N3O 319.1685,
Found 319.1685; H NMR (400 MHz, CDCl3) d 2.18
(3H, s), 2.78±2.82 (2H, m), 3.80±3.83 (2H, m), 5.33 (1H,
br s), 5.52 (1H, br s), 6.56 (1H, s), 7.21±7.41 (11H, m).
1
4-(1-Imidazolyl)-2,2-diphenylbutyramide (1). High MS
(EI+) m/z calcd for C19H19N3O 305.1528, found
305.1523; 1H NMR (400 MHz, CDCl3) d 2.80±2.84 (2H,
m), 3.88 (2H, m), 5.36 (1H, s), 5.71 (1H, s), 6.84 (1H, s),
6.99 (1H, s), 7.30±7.41 (10H, m).
4-(5-Methyl-1-imidazolyl)-2,2-diphenylbutyramide (11).
High MS (EI+) m/z calcd for C20H21N3O 319.1685,
1
Found 319.1667; H NMR (400 MHz, CDCl3) d 2.08

H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
1159
(3H, s), 2.69±2.73 (2H, m), 3.78±3.82 (2H, m), 5.33 (1H,
s), 5.51 (1H, s), 6.70 (1H, s), 7.27±7.42 (11H, m).
(3H, s), 2.24 (3H, s), 2.27±2.41 (2H, m), 3.64±3.72 (1H,
m), 3.74±3.82 (1H, m), 5.20 (1H, br s), 5.36 (1H, br s),
6.73 (1H, d, J=1.5 Hz), 6.86 (1H, d, J=1.5 Hz), 7.32±
7.42 (5H, m).
4-(1-Benzimidazolyl)-2,2-diphenylbutyramide (12). High
MS (EI+) m/z calcd for C23H21N3O 355.1685, Found
355.1693; 1H NMR (400 MHz, CDCl3) d 2.85±2.89 (2H,
m), 4.15±4.19 (2H, m), 5.37 (1H, s), 5.59 (1H, s), 7.23±
7.43 (13H, m), 7.73±7.78 (2H, m).
2-Isopropyl-2-phenyl-4-(2-methyl-1-imidazolyl)butyramide
(21). High MS (EI+) m/z calcd for C17H23N3O
285.1841, Found 285.1858; 1H NMR (400 MHz,
CDCl3) d 0.92 (3H, d, J=6.8 Hz), 1.03 (3H, d, J=
6.8 Hz), 2.00±2.15 (1H, m), 2.22 (3H, s), 2.50±2.65 (2H,
m), 3.40±3.55 (1H, m), 3.75±3.85 (1H, m), 5.38 (1H, br
s), 5.65 (1H, br s), 6.72 (1H, s), 6.86 (1H, s), 7.34±7.36
(3H, m), 7.39±7.43 (2H, m).
5-(2-Methyl-1-imidazolyl)-2,2-diphenylpentyramide (13).
High MS (EI+) m/z calcd for C21H23N3O 333.1841,
1
Found 333.1841; H NMR (400 MHz, CDCl3) d 1.62±
1.70 (2H, m), 2.30 (3H, s), 2.36 (2H, m), 3.77 (2H, t,
J=7.1 Hz), 5.35 (1H, br s), 5.42 (1H, br s), 6.74 (1H, d,
J=1.0 Hz), 6.89 (1H, d, J=1.0 Hz), 7.25±7.37 (10H, m).
2-Cyclohexyl-2-(4-methoxyphenyl)-4-(2-methyl-1-imida-
zolyl)butyramide (22). High MS (EI+) m/z calcd for
C20H27N3O 325.2154, Found 325.2150; 1H NMR
(400 MHz, CDCl3) d 0.90±1.10 (1H, m), 1.10±1.25 (2H,
m), 1.40±1.60 (2H, m), 1.85±2.00 (5H, m), 2.05±2.20 (1H,
m), 2.27 (1H, dt, J=13, 4.9 Hz), 2.36 (3H, s), 2.70 (1H, dt,
J=13, 4.9 Hz), 3.67 (1H, dt, J=13, 4.9 Hz), 3.91 (1H, dt,
J=13, 4.9 Hz), 5.54 (1H, br s), 5.72 (1H, br s), 6.87 (1H,
s), 7.02 (1H, s), 7.47±7.50 (3H, m), 7.54±7.58 (2H, m).
6-(2-Methyl-1-imidazolyl)-2,2-diphenylhexyramide (14).
High MS (EI+) m/z calcd for C22H25N3O 347.1998,
1
Found 347.1994; H NMR (400 MHz, CDCl3) d 1.23
(2H, m), 1.68 (2H, dt, J=7.8, 7.3 Hz), 2.28 (3H, s), 2.39
(2H, m), 3.71 (2H, t, J=7.3 Hz), 5.48 (2H, br s), 6.70 (1H,
d, J=1.5 Hz), 6.84 (1H, d, J=1.5 Hz), 7.27±7.37 (10H, m).
7-(2-Methyl-1-imidazolyl)-2,2-diphenylheptyramide (15).
High MS (EI+) m/z calcd for C23H27N3O 361.2154,
Found 361.2155; H NMR (400 MHz, CDCl3) d 1.20±
1.30 (4H, m), 1.63±1.66 (2H, m), 2.31 (3H, s), 2.34±2.38
(2H, m), 3.73 (2H, t, J=7.1 Hz), 5.30±5.50 (2H, m), 6.73
(1H, s), 6.87 (1H, s), 7.28±7.35 (10H, m).
2-Pyridyl-4-(2-methyl-1-imidazolyl)-2-phenylbutyramide
(23). High MS (EI+) m/z calcd for C19H20N4O
320.1637, Found 320.1671; 1H NMR (400 MHz,
CDCl3) d 2.23 (3H, s), 2.76 (1H, dt, J=6.8, 4.9 Hz), 2.82
(1H, dt, J=6.8, 4.9 Hz), 3.66±3.73 (1H, m), 3.86±3.92
(1H, m), 5.66 (1H, br s), 6.75 (1H, s), 6.86 (1H, s), 7.18±
7.20 (2H, m), 7.26±7.37 (5H, m), 7.73 (1H, t, J=7.8 Hz),
7.80 (1H, br s), 8.61 (1H, d, J=3.9 Hz).
1
3-Methyl-4-(2-methyl-1-imidazolyl)-2,2-diphenylbutyr-
amide (16). High MS (EI+) m/z calcd for C21H23N3O
333.1841, Found 333.1851; 1H NMR (400 MHz,
CDCl3) d 0.81 (3H, d, J=6.8 Hz), 2.29 (3H, s), 2.90±
3.10 (1H, m), 3.40±3.50 (1H, m), 4.17 (1H, s), 5.46 (2H,
br s), 6.84 (1H, s), 6.88 (1H, s), 7.30±7.44 (10H, m).
5-Carbamoyl-5-[4-(2-methyl-1-imidazoly)ethyl]dibenzo-
suberane (24). 5-Cyano-5-[4-(2-methyl-1-imidazoly)eth-
yl]dibenzosuberane (2.00 g, 6.11 mmol) was mixed with
KOH (2.00 g, 35.6 mmol), EtOH (20 mL), and water
(20 mL) in an autoclave and stirred for 20 h at 150 ꢀC.
The mixture was diluted with water, extracted with
CH2Cl2 and the extract was washed, dried (Na2SO4),
and concentrated. The residue was puri®ed by silica gel
column chromatography, eluting with CH2Cl2:ethanol
(12:1 v/v), recrystallized from a mixed solvent of n-hex-
ane and ethyl acetate to give the compound (500 mg,
24%) as a colorless powder: mp 218.0±220.0 ꢀC; High
MS (EI+) m/z calcd for C22H23N3O 345.1841, Found
4-Methyl-4-(2-methyl-1-imidazolyl)-2,2-diphenylbutyr-
amide (17). High MS (EI+) m/z calcd for C21H23N3O
333.1841, Found 333.1866; 1H NMR (400 MHz,
CDCl3) d 1.22 (3H, d, J=6.8 Hz), 1.77 (3H, s), 2.83 (1H,
dd, J=14, 5.1 Hz), 2.97 (1H, dd, J=14, 5.1 Hz), 4.30±
4.40 (1H, m), 5.29 (1H, br s), 5.55 (1H, br s), 6.80 (1H,
s), 6.82 (1H, s), 7.19±7.33 (10H, m).
2,2-Bis-(4-¯uorophenyl)-4-(2-methyl-1-imidazolyl)butyr-
amide (18). High MS (EI+) m/z calcd for C20H19F2
1
345.1834; H NMR (400 MHz, CDCl3) d 2.17 (3H, s),
1
N3O 355.1496, Found 355.1497; H NMR (400 MHz,
2.65±2.70 (2H, m), 3.17 (4H, s), 3.62 (2H, m), 5.10 (1H,
br s), 5.45 (1H, br s), 6.66 (1H, s), 6.84 (1H, s), 7.17±7.26
(6H, m), 7.44 (2H, d, J=6.4 Hz).
CDCl3) d 2.41 (3H, s), 2.66±2.70 (2H, m), 3.83±3.87 (2H,
m), 5.30 (1H, br s), 5.62 (1H, br s), 6.79 (1H, s), 6.98 (1H,
s), 7.11 (4H, t, J=8.8 Hz), 7.28 (4H, dd, J=8.8, 5.3 Hz).
A similar procedure was employed for the preparation
of compound 25.
2-(4-Methoxyphenyl)-4-(2-methyl-1-imidazolyl)-2-phenyl-
butyramide (19). High MS (EI+) m/z calcd for
C21H23N3O2 349.1790, Found 349.1790; 1H NMR
(400 MHz, CDCl3) d 2.32 (3H, s), 2.66±2.70 (2H, m),
3.79±3.87 (2H, m), 3.83 (3H, s), 5.35 (1H, br s), 5.58
(1H, br s), 6.77 (1H, s), 6.91 (1H, s), 6.92 (2H, d,
J=8.8 Hz), 7.22 (2H, d, J=8.8 Hz), 7.31±7.42 (5H, m).
9-Carbamoyl-9-[4-(2-methyl-1-imidazoly)ethyl]xanthene
(25). High MS (EI+) m/z calcd for C20H19N3O2
333.1477, Found 333.1460; 1H NMR (400 MHz,
CDCl3) d 2.00 (3H, s), 2.62±2.66 (2H, m), 3.36±3.41
(2H, m), 5.27 (1H, br s), 5.54 (1H, br s), 6.54 (1H, s),
6.75 (1H, s), 7.15±7.19 (4H, m), 7.34±7.40 (4H, m).
2-Methyl-2-phenyl-4-(2-methyl-1-imidazolyl)butyramide
(20). High MS (EI+) m/z calcd for C15H19N3O 257.1528,
Found 257.1522; H NMR (400 MHz, CDCl3) d 1.67
4-(2-Methyl-1-imidazolyl)-2,2-diphenylbutyronitrile HCl
(26). High MS (EI+) m/z calcd for C20H19N3 301.1579,
1

1160
H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
1
Found 301.1578; H NMR (400 MHz, CDCl3) d 2.25
(3H, s), 2.75±2.79 (2H, m), 3.90±3.94 (2H, m), 6.77 (1H,
s), 6.90 (1H, s), 7.35±7.42 (10H, m).
2.68±2.72 (2H, m), 3.89±3.93 (2H, m), 4.24 (2H, s),
7.13±7.35 (12H, m).
N-Methyl 4-(2-methyl-1-imidazolyl)-2,2-diphenylbutyra-
mide (31). A mixture of compound (29) (1.00 g,
2.80 mmol) and thionyl chloride (20 mL) was re¯uxed
for 4 h and evaporated o€ excess thionyl chloride. Then,
the residual acid chloride was mixed with 40% aqueous
methylamine (30 mL) and CH2Cl2 (100 mL), stirred for
6 h under ice-cooling. The mixture was poured into
water, then basi®ed with NaOH, and extracted with
CH2Cl2. The organic solvent was evaporated and the
residue was puri®ed by silica gel column chromato-
graphy, eluting with CH2Cl2:ethanol (10:1 v/v), recrys-
tallized from ethyl acetate to give the product (800 mg,
86%) as a colorless powder: mp 153.0±154.5 ꢀC; High
MS (EI+) m/z calcd for C21H23N3O 333.1841, Found
3-(2-Methyl-1-imidazolyl)-1,1-diphenylpropanol (27). To
a mixture of ethyl 3-(2-methyl-1-imidazolyl) propionate
(3.37 g, 18.5 mmol) and dehydrated THF (10 mL) was
added a solution of phenyl lithium in cyclohexane:ether
(1.8 M solution, 50 mL) at 0 ꢀC. The mixture was stirred
for 3.5 h at 10 ꢀC, poured into water, extracted with ethyl
acetate, then the extract was washed with brine, dried
(Na2SO4), and concentrated. The residue was puri®ed by
silica gel column chromatography, eluting with ethyl
acetate:ethanol (10:1 v/v), recrystallized from a mixed
solvent of ethanol and benzene to give the product
(320 mg, 6%) as a colorless needle: mp 212.0±214.0 ꢀC;
High MS (EI+) m/z calcd for C19H20N2O 292.1576,
1
1
Found 292.1589; H NMR (400 MHz, CDCl3) d 2.18
(3H, s), 2.64±2.69 (2H, m), 2.90 (1H, br s), 3.79±3.84
(2H, m), 6.72 (1H, s), 6.80 (1H, s), 7.22±7.44 (10H, m).
333.1863; H NMR (400 MHz, CDCl3) d 2.24 (3H, s),
2.68±2.72 (2H, m), 2.80 (3H, d, J=4.9 Hz), 3.82±3.87
(2H, m), 5.36 (1H, br s), 6.73 (1H, s), 6.84 (1H, s), 7.22±
7.27 (4H, m), 7.33±7.40 (6H, m).
Methyl 4-(2-methyl-1-imidazolyl)-2,2-diphenylbutyrate
(28). A mixture of compound (29) (2.00 g, 5.60 mmol)
and thionyl chloride (20 mL) was re¯uxed for 4 h and
evaporated o€ excess thionyl chloride. Then, the resi-
dual acid chloride was mixed with methanol (100 mL),
re¯uxed for 18 h. The solvent was evaporated and the
residue was puri®ed by silica gel column chromato-
graphy, eluting with ethyl CH2Cl2:ethanol (10:1 v/v),
recrystallized from n-hexane:ethyl acetate to give the
product (250 mg, 13%) as a colorless powder: mp 84.0±
86.0 ꢀC; High MS (EI+) m/z calcd for C21H22N2O2
334.1681, Found 334.1679; 1H NMR (400 MHz,
CDCl3) d 2.20 (3H, s), 2.69±2.73 (2H, m), 3.58-3.62 (2H,
m), 3.75 (3H, s), 3.58±3.62 (2H, m), 3.75 (3H, s), 6.71
(1H, s), 6.87 (1H, s), 7.24±7.37 (10H, m).
A similar procedure was employed for the preparation
of compound 32.
N,N-Dimethyl 4-(2-methyl-1-imidazolyl)-2,2-diphenyl-
butyramide (32). High MS (EI+) m/z calcd for C22H25
1
N3O 347.1998, Found 347.2007; H NMR (400 MHz,
CDCl3) d 2.20 (3H, s), 2.34 (3H, s), 2.50±2.54 (2H, m),
3.03 (3H, s), 3.54±3.57 (2H, m), 6.41 (1H, s), 6.79 (1H,
s), 7.32±7.35 (2H, m), 7.42±7.43 (8H, m).
4-(2,3-Dimethyl-1-imidazolyl)-2,2-diphenylbutyramide io-
dide (33). A mixture of compound 2 (1.00 g, 3.13 mmol),
methyliodide (20 mL), acetone (100 mL) and ethanol
(10 mL) was stirred for 18 h at 95 ꢀC in a sealed tube.
The solvent was evaporated and the residue was recrys-
tallized from ethyl acetate:ethanol to a€ord 1.30 g
(90%) of the desired salts as a yellow needle: mp 234.0±
236.0 ꢀC; High MS (FAB+) m/z calcd for C21H24N3O
334.1919, Found 334.1917; 1H NMR (400 MHz,
DMSO-d6) d 2.38 (3H, s), 2.73 (2H, m), 3.69 (3H, s),
3.77 (2H, m), 6.80 (1H, s), 7.32±7.41 (10H, m), 7.46 (1H,
s), 7.53 (1H, d, J=2.0 Hz), 7.56 (1H, d, J=2.0 Hz).
4-(2-Methyl-1-imidazolyl)-2,2-diphenylbutyric acid mono-
hydrochloride (29). A mixture of compound 2 (5.00 g,
15.7 mmol) and c.HCl (250 mL) was stirred for 18 h at
150 ꢀC and then cooled to room temperature. The pre-
cipitate was ®ltrated and washed with acetone to a€ord
4.70 g (84%) of the product as a white powder: mp
237.0 ꢀC; High MS (EI+) m/z calcd for C20H20N2O2
320.1525, Found 320.1530; 1H NMR (400 MHz,
DMSO-d6) d 2.38 (3H, s), 2.80±2.84 (2H, m), 3.77±3.81
(2H, m), 7.28±7.39 (10H, m), 7.51 (1H, s), 7.55 (1H, s).
A similar procedure was employed for the preparation
of the compounds 34±40. The yields were 40±90%.
4-(2-Methyl-1-imidazolyl)-2,2-diphenylbutanol (30). To a
solution of 70% sodium bis (2-methoxyethoxy)alumi-
nium hydride and benzene (80 mL) was added dropwise
a solution of compound (28) (2.00 g, 5.81 mmol) and
benzene (20 mL) under re¯ux. Re¯ux was continued for
6 h, poured into 20% KOH solution, and the mixture
was re¯uxed for 30 min. The mixture was poured into
water and extracted with benzene. The organic solution
was washed with brine, dried (Na2SO4), and con-
centrated. The residue was puri®ed by silica gel column
chromatography, eluting with CH2Cl2:ethanol (12:1 v/v),
recrystallized from acetone to give the product (1.00 g,
39%) as a colorless needle: mp 155.0±156.5 ꢀC; High
MS (EI+) m/z calcd for C20H22N2O 306.1732, Found
4-(3-Ethyl-2-methyl-1-imidazolyl)-2,2-diphenylbutyramide
iodide (34). High MS (FAB+) m/z calcd for C22H26N3O
348.2076, Found 348.2077; 1H NMR (400 MHz,
DMSO-d6) d 1.31 (3H, t, J=7.3 Hz), 2.41 (3H, s), 2.76
(2H, m), 3.80 (2H, m), 4.08 (2H, q, J=7.3 Hz), 6.78
(1H, s), 7.33±7.41 (10H, m), 7.46 (1H, s), 7.57 (1H, s),
7.64 (1H, s).
4-(3-n-Propyl-2-methyl-1-imidazolyl)-2,2-diphenylbutyra-
mide iodide (35). High MS (FAB+) m/z calcd for
C23H28N3O 362.2232, Found 362.2234; 1H NMR
(400 MHz, DMSO-d6) 0.86 (3H, t, J=7.3 Hz), 1.70±1.72
(2H, m), 2.42 (3H, m), 2.77 (2H, m), 3.80 (2H, m), 4.02
(2H, t, J=7.3 Hz), 6.78 (1H, s), 7.31±7.40 (10H, m), 7.45
(1H, s), 7.58 (1H, s), 7.63 (1H, s).
1
306.1735; H NMR (400 MHz, CDCl3) d 2.53 (3H, s),

H. Miyachi et al. / Bioorg. Med. Chem. 7 (1999) 1151±1161
1161
4-(3-n-Butyl-2-methyl-1-imidazolyl)-2,2-diphenylbutyra-
mide iodide (36). High MS (FAB+) m/z calcd for
C24H30N3O 376.2389, Found 376.2393; 1H NMR
(400 MHz, DMSO-d6) 0.90 (3H, t, J=7.3 Hz), 1.26 (2H,
quint, J=7.3 Hz), 1.66 (2H, m), 2.41 (3H, s), 2.76 (2H,
m), 3.80 (2H, m), 4.05 (2H, t, J=7.3 Hz), 6.78 (1H, s),
7.31±7.40 (10H, m), 7.45 (1H, s), 7.57 (1H, d, J=
2.4 Hz), 7.63 (1H, d, J=2.4 Hz).
4. Kelly, L.-U.; Wehnert, J. Z. Urol. Nephrol. 1979, 72, 765.
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9. Levine, R. R.; Birdsall, N. J. M. Trends. Pharmacol. Sci.
1989, Dec. Supple. VII.
4-(3-Benzyl-2-methyl-1-imidazolyl)-2,2-diphenylbutyramide
iodide (37). High MS (FAB+) m/z calcd for C27H28N3O
410.2232, Found 410.2221; 1H NMR (400 MHz,
DMSO-d6) d 2.44 (3H, s), 2.77±2.81 (2H, m), 3.80±3.84
(2H, m), 5.36 (2H, s), 6.79 (1H, s), 7.45 (1H, s), 7.30±7.43
(15H, m), 7.64 (1H, d, J=2.4Hz), 7.68 (1H, d, J=2.0Hz).
10. Hammer, R.; Berrie, C. P.; Birdsall, N. J. M.; Burgen,
A. S. V.; Hulme, E. C. Nature (London), 1980, 283, 90.
11. Barlow. R.; Berry, K. J.; Glenton, P. A. M.; Nikolaou,
N. M.; Soh, K. S. Br. J. Pharmacol. 1976, 58, 613.
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1988, 239, 339.
14. Dorje, F.; Levey, A. I.; Brann, M. R. Mol. Pharmacol.
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Ther. 1995, 273, 959.
16. Langtry, H. D.; McTavish, D. Drugs 1990, 40, 748. Ter-
odiline was recently withdrawn from the market because of its
cardiovascular side-e€ects.
4-(2-Ethyl-3-methyl-1-imidazolyl)-2,2-diphenylbutyramide
iodide (38). High MS (FAB+) m/z calcd for C22H26N3O
348.2076, Found 348.2065; 1H NMR (400 MHz,
DMSO-d6) d 1.02 (3H, t, J=7.6 Hz), 2.77±2.79 (4H, m),
3.75 (3H, s), 3.79±3.84 (2H, m), 6.82 (1H, s), 7.32±7.41
(10H, m), 7.46 (1H, s), 7.59 (1H, s), 7.61 (1H, s).
17. (a) Miyachi, H.; Kiyota, H.; Segawa, M. Bioorg. Med.
Chem. Letters. 1998, 8, 1807. (b) Miyachi, H.; Kiyota, H.;
Segawa, M. Bioorg. Med. Chem. Letters 1998, 8, 2163.
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21. A Phase I clinical study of KRP-197 is in progress.
22. Attenburrow, J.; Elks, J.; Hems, B. A.; Speyer, K. N. J.
Chem. Soc. 1949, part 1. 510.
4-(3-Methyl-2-n-propyl-1-imidazolyl)-2,2-diphenylbutyra-
mide iodide (39). High MS (FAB+) m/z calcd for
C23H28N3O 362.2232, Found 362.2242; 1H NMR
(400 MHz, DMSO-d6) 0.83 (3H, t, J=7.3 Hz), 1.39±1.41
(2H, m), 2.69±2.73 (4H, m), 3.75 (3H, s), 3.81 (2H, m),
6.83 (1H, s), 7.34±7.42 (10H, m), 7.48 (1H, s), 7.61 (1H,
s), 7.66 (1H, d, J=2.0 Hz).
23. Hall, J. H.; Gisler, M. J. Org. Chem. 1976, 41, 3769.
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Czech. Chem. Comm. 1969, 34, 1025.
4-(2-Isopropyl-3-methyl-1-imidazolyl)-2,2-diphenylbutyra-
mide iodide (40). High MS (FAB+) m/z calcd for
C23H28N3O 362.2232, Found 362.2245; 1H NMR
(400 MHz, DMSO-d6) d 1.16 (6H, d, J=7.3 Hz), 2.73±
2.78 (2H, m), 3.24±3.30 (1H, m), 3.81±3.88 (5H, m), 6.88
(1H, s), 7.31±7.43 (10H, m), 7.46 (1H, s), 7.61 (1H, s),
7.64 (1H, s).
25. Ejima, K.; Matsushita, Y.; Sekine, M.; Nishide, H.;
Tsuchida, E. Nippon Kagaku Kaishi. 1983, 2, 214.
26. Kaiser, C.; Spagnuolo, C. J.; Adams, T. C. Jr.; Audia, V. H.;
Dupont, A. C.; Hatoum, H.; Lowe, V. C.; Prosser, J. C.;
Sturm, B. L.; Noronha-Blob, L. J. Med. Chem. 1992, 35, 4415.
27. Willfert, B.; Davidesko, D.; Timmermans, P. B. M. W. M.;
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28. Evans, D. B.; Schenden, J. A.; Bristol, J. A. Life Sci. 1982,
31, 2425.
Pharmacology
In vitro functional antimuscarinic activity of the com-
pounds described in this paper (rabbit vas deferens
(M1 receptor antagonism), guinea pig atrial muscle (M2
receptor antagonism), guinea pig ileal muscle (M3
receptor antagonism)) were determined according to the
literature method.3 In vivo antimuscarinic activity of the
selected compound (KRP-197) (isovolumetric bladder
contraction,31 carbachol±induced detrusor hyperre-
¯exia,32 inhibition of pupil diameter,35 inhibition of
salivary gland secretion,34 inhibition of gut motilities,31
and inhibition of serotonin-induced bradycardia33) were
determined according to the literature methods.
29. Arunlakshana, O.; Schild, H. O. Br. J. Pharmacol. 1959,
14, 48.
30. Molecular modeling was done on a Silicon Graphics IRIS
4D/35 workstation using the software package QUANTA,
version 3.3, from Molecular Simulations Inc., San Diego, CA.
The energies for conformations of compounds (2) and (33)
were minimized with the CHARMm 23 force ®eld (adopted-
basis Newton±Raphson method and 0.001 kcal/mol A energy
convergence criterion). The pictures were visualized by Insight
II 97.1 (Molecular Simulations Inc.).
31. Morikawa, K.; Yamauti, T.; Katoh, H.; Itoh, Y. Folia.
Pharmacol. Japon. 1986, 88, 355.
32. Igawa, Y.; Mattiasson, A.; Andersson, K.-E. Brit. J.
Pharmacol. 1993, 109, 473.
33. Schneider, J. A.; Yonkman, F. F. J. Pharmacol. Exp.
Ther. 1954, 111, 84.
References and Notes
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34. Zwagemakers, J. M. A.; Claassen, V. Arzneim. -Forsch./
Drug Res. 1980, 30, 1517.
2. Anderson, K.-E. Pharmacol. Rev. 1993, 45, 253.
3. Noronha-Blob, L.; Kachur, J. F. J. Pharmacol. Exp. Ther.
1991, 256, 562.
35. Bogner, I. T.; Baumann, B.; Dammann, F.; Knoll, B.;
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163, 263.