Identification of 1-methyl-N-(propan-2-yl)-N-({2-[4-(trifluoromethoxy)-phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide as a potent and orally available glycine transporter 1 inhibitor

Article abstract of DOI:10.1248/cpb.c16-00610

We previously identified 3-chloro-N-{(S)-[3-(1-ethyl-1H-pyrazol-4-yl)phenyl][(2S)-piperidine-2-yl]methyl}-4-(trifluoromethyl)pyridine-2-carboxamide (5, TP0439150) as a potent and orally available glycine transporter 1 (GlyT1) inhibitor. In this article, we describe our identification of 1-methyl-N-(propan-2-yl)-N-({2-[4-(trifluoromethoxy)phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide (7n) as a structurally diverse back-up compound of 5, using central nervous system multiparameter optimization (CNS MPO) as a druglikeness guideline. Compound 7n showed a higher CNS MPO score and different physicochemical properties as compared to 5. Compound 7n exhibited potent GlyT1 inhibitory activity, a favorable pharmacokinetics profile, and elicited an increase in the cerebrospinal fluid (CSF) concentration of glycine in rats.

Full text of DOI:10.1248/cpb.c16-00610

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Chem. Pharm. Bull. 64, 1630–1640 (2016)
Vol. 64, No. 11
Regular Article
Identification of 1-Methyl-N-(propan-2-yl)-N-({2-[4-(trifluoromethoxy)-
phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide as a Potent
and Orally Available Glycine Transporter 1 Inhibitor
,a
Shuji Yamamoto,* Hiroshi Ohta,a Kumi Abe,a Daiji Kambe,b Naohiro Tsukiyama,b
Yasunori Kawakita,c Minoru Moriya,a and Akito Yasuharaa
a Chemistry Laboratories, Taisho Pharmaceutical Co., Ltd.; 1–403 Yoshino-cho, Kita-ku, Saitama 331–9530, Japan:
b Pharmacology Laboratories, Taisho Pharmaceutical Co., Ltd.; 1–403 Yoshino-cho, Kita-ku, Saitama 331–9530,
c
Japan: and Drug Safety and Pharmacokinetics Laboratories, Taisho Pharmaceutical Co., Ltd.; 1–403 Yoshino-cho,
Kita-ku, Saitama 331–9530, Japan.
Received July 28, 2016; accepted August 29, 2016
We previously identified 3-chloro-N-{(S)-[3-(1-ethyl-1H-pyrazol-4-yl)phenyl][(2S)-piperidine-2-yl]meth-
yl}-4-(trifluoromethyl)pyridine-2-carboxamide (5, TP0439150) as a potent and orally available glycine trans-
porter 1 (GlyT1) inhibitor. In this article, we describe our identification of 1-methyl-N-(propan-2-yl)-N-({2-
[4-(trifluoromethoxy)phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide (7n) as a structurally diverse
back-up compound of 5, using central nervous system multiparameter optimization (CNS MPO) as a drug-
likeness guideline. Compound 7n showed a higher CNS MPO score and different physicochemical properties
as compared to 5. Compound 7n exhibited potent GlyT1 inhibitory activity, a favorable pharmacokinetics
profile, and elicited an increase in the cerebrospinal fluid (CSF) concentration of glycine in rats.
Key words glycine transporter 1 inhibitor; schizophrenia; multiparameter optimization; structure–activity
relationship
Hypofunction of the N-methyl-D-aspartate (NMDA) recep- phencyclidine treatment in mice. These results suggest that 5
tor is implicated in the pathophysiology of schizophrenia, would be useful for the treatment of the cognitive dysfunc-
based on the results of clinical observation and pre-clinical tion and negative symptoms of schizophrenia. In parallel with
studies.1–4) Stimulation of the NMDA receptor may improve further pharmacological studies of 5, our medicinal chemistry
the symptoms of schizophrenia, but direct activation of the efforts have been focused on the identification of structurally
glutamate-binding site has been reported to induce neurotoxic- diverse back-up compounds.
ity.5) Under this circumstance, it was considered that elevating
There are several drug-likeness guidelines for enhanc-
the extracellular levels of glycine would be an effective alter- ing the probability of success in drug discovery.17,18) Wager
native approach, as glycine is an important co-agonist of the et al. at Pfizer have proposed the Central Nervous System
NMDA receptor. In fact, co-administration of glycine, or of Multiparameter Optimization (CNS MPO) as a drug-likeness
the glycine site agonist D-serine, with atypical antipsychotics guideline for the development of drugs acting on the CNS.19)
has been reported to improve schizophrenia.6)
The CNS MPO score is calculated using six physicochemical
Elevating glycine levels in the brain can be achieved by parameters: (1) calculated distribution coefficient (cLogP);
inhibition of the glycine transporter 1 (GlyT1) which is co- (2) calculated distribution coefficient at pH 7.4 (cLogD); (3)
expressed with the NMDA receptor.7,8) This approach is sup- molecular weight (MW); (4) topological polar surface area
ported by the results of clinical studies on sarcosine (N-meth- (tPSA); (5) number of hydrogen bond donor (HBD); (6) pKa of
ylglycine, a prototypical weak GlyT1 inhibitor); administration the most basic center; it has been reported that a higher CNS
of sarcosine with atypical antipsychotics has been shown to MPO score may increase of the probability of success. While
improve the positive, negative, as well as cognitive symptoms the CNS MPO scores of 74% of the CNS drugs launched in
in schizophrenic patients.9)
Many research groups have reported the development of (Fig. 2). Precise analysis of its each parameter indicated that
GlyT1 inhibitors, as illustrated in Fig. 1: 1 (RG1678),10)
this relatively low score was due to its high MW, lipophilic
(DCCCyB),11) and 3a (PF-0346275).12) Compound 413) has characteristic (cLogP), and basicity (pKa).
the market are more than 4.0, the calculated score of 5 is 3.17
2
been also reported as the hybrid compound of 3a and Merck’s
In this article, we report our exploration and identification
sulfonamide derivatives.14,15) Recently, our group discovered of the structurally diverse GlyT1 inhibitor 7n, based on the
5 (TP0439150), and reported its pharmacological profile.16) CNS MPO guideline.
Compound 5 shows potent in vitro GlyT1 inhibitory activity
with an IC50 value of 1.8nM; oral dosing at 1mg/kg elicited an
increase in the concentration of glycine in the cerebrospinal
Chemistry
Compounds were prepared as shown in Charts 1 to 3.
fluid (CSF) in rats. Furthermore, at doses of 0.1 and 0.3mg/ Compounds with various alkyl groups at the nitrogen atom
kg, respectively, 5 significantly improved cognitive deficit in- of the amide bond were prepared according to Chart 1. Con-
duced by MK-801 in the social recognition test in rats and re- densation of 1-methyl-1H-imidazole-4-carboxylic acid with
versed the reduction in social interaction induced by repeated 3-(trifluoromethoxy)benzylamine 8 yielded amide intermediate
*To whom correspondence should be addressed. e-mail: shu-yamamoto@so.taisho.co.jp
© 2016 The Pharmaceutical Society of Japan

Vol. 64, No. 11 (2016)
Chem. Pharm. Bull.
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Fig. 1. Structure of Reported GlyT1 Inhibitors and in Vitro GlyT1 Inhibitory Activity (Literature Value)
Fig. 2. CNS MPO Analysis of 5
(a) Value of each parameter and CNS MPO score of each component; (b) Radar chart based on each component of CNS MPO.
Reagents and conditions: (a) 1-Methyl-1H-imidazole-4-carboxylic acid, HOBt, EDC, acetonitrile; (b) NaH, R-I, DMF; (c) Acetone or cyclohexanone or tetrahydro-2H-
pyran-4-one, NaBH(OAc)3, CHCl3.
Chart 1

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Reagents and conditions: (a) 1-Aminopropane or 2-aminopropane, NaBH(OAc)3, CHCl3; (b) 1-Methyl-1H-imidazole-4-carboxamide, HOBt, EDC, acetonitrile; (c) (Condi-
tion A) Ar2-B(OH)2, Pd(PPh3)4, K2CO3, DMF, EtOH, 150°C, microwave irradiation (condition B) Ar2-B(OH)2, Pd(PPh3)4, Cs2CO3, toluene, EtOH, H2O, 150°C, microwave
irradiation.
Chart 2
Reagents and conditions: (a) 1-Aminopropane, HOBt, EDC, acetonitrile; (b) PhB(OH)2, Pd(PPh3)4, K2CO3, DMF, EtOH, 150°C, microwave irradiation; (c) LiAlH4, THF,
70°C; (d) 1-Methyl-1H-imidazole-4-carboxamide, HOBt, EDC, acetonitrile.
Chart 3
9, which was alkylated with alkyl halide using sodium hydride 1-aminopropane yielded 18, which was converted to 19 by the
to obtain 6a–c and e. The introduction of secondary alkyl Suzuki coupling reaction with phenylboronic acid. The amide
groups, such as the i-propyl, cyclohexyl, or tetrahydro-2H- moiety of 19 was reduced by lithium aluminium hydride, and
pyran-4-yl groups, was conducted by reductive amination of subsequent condensation with 1-methyl-1H-imidazole-4-car-
the corresponding ketones with 8. Intermediates 10a–c were boxylic acid yielded 7b.
condensed with 1-methyl-1H-imidazole-4-carboxylic acid to
obtain 6d, f, and g.
Results and Discussion
The synthetic routes for compounds 7a and c–o are de-
As mentioned above, we placed a high priority on the CNS
picted in Chart 2. Reductive amination of 2-bromopyridine- MPO score for exploration of our back-up lead compound.
6-carboxaldehyde 11 with 1-aminopropane or 2-aminopropane Through these efforts, we found that 6a, which was designed
yielded 12a and b, which were condensed with 1-methyl-1H- by removal of the basic amine substructure of 3b,12) retained
imidazole-4-carboxylic acid to obtain intermediates 13a and moderate GlyT1 inhibitory activity with a CNS MPO score of
b, respectively. Subsequently, the Suzuki coupling reaction 5.96 (Fig. 3). This high score was due to the different physi-
with phenylboronic acid yielded 7a and d, respectively. In a cochemical characteristics of 6a ((1) low molecular weight
similar manner, 2-phenyl-4-pyridyl derivatives, 7c and e–o, (=313), (2) low lipophilicity (cLogP=2.0), and (3) weak ba-
were synthesized using 2-bromopyridine-4-carboxaldehyde 14 sicity (calculated pKa=4.2)) as compared to those of GlyT1
as the starting material.
inhibitor 5 reported by us previously. Thus, we decided to
The synthesis of compound 7b is shown in Chart 3. Con- optimize 6a to obtain a back-up candidate with a higher CNS
densation of 4-bromopyridine-2-carboxylic acid 17 with MPO score than 5.

Vol. 64, No. 11 (2016)
Chem. Pharm. Bull.
1633
Fig. 3. Identification of the Initial Lead Compound 6a
Table 1. In Vitro GlyT1 Inhibitory Activity of Compounds 6a–g
Table 2. In Vitro GlyT1 Inhibitory Activity of Compounds 7a–e
No.
R
IC50 (nM)
CNS MPO
No.
R
Ar1
IC50 (nM)
140
CNS MPO
6a
6b
6c
6d
6e
6f
Me
67
5.96
5.78
5.58
5.66
5.23
4.55
5.54
Et
76
n-Pr
10
7a
n-Pr
5.78
5.78
5.78
5.81
5.81
i-Pr
2.7
2.8
1.6
4.7
i-Bu
c-Hex
6g
Tetrahydro-2H-pyran-4-yl
7b
7c
7d
7e
n-Pr
n-Pr
i-Pr
i-Pr
1400
39
Firstly, the alkyl group at the nitrogen atom of the amide
linker was explored (Table 1). While elongation of the methyl
group to ethyl group was associated with retention of equiva-
lent activity (6b: IC50=76 nM), the n-propyl derivative 6c
showed higher activity (6c: IC50=10 nM). Moreover, introduc-
tion of a branch alkyl substituent, such as an i-propyl or i-
butyl group, increased the inhibitory activity (6d: IC50=2.7 nM,
6e: IC50=2.8nM). More bulky substituents, such as a cyclo-
hexyl or tetrahydro-2H-pyran-4-yl group, were also tolerated
(6f: IC50=1.6 nM, 6g: IC50=4.7 nM), however, their CNS MPO
scores were lower than the score of 6d, due to their higher
molecular weight. Since 6d exhibited a CNS MPO score of
more than 5.0, with maintenance of potent inhibitory activity,
we selected the n-propyl or i-propyl group as the alkyl group
at the nitrogen atom of the amide bond for further structure–
activity relationship (SAR) studies.
100
20
(7a vs. d, and 7c vs. e). All the phenylpyridine derivatives
Secondly, modification of the side chain moieties was listed in Table 2 showed high CNS MPO scores; therefore, our
investigated to introduce further structural novelty into the efforts were focused on optimization of the substituents on the
lead compound 6d. The left-hand side moiety (left hand, phenyl ring.
LH), 1-methyl-1H-imidazole-4-carboxamide, was essential for
Introduction of the electron-withdrawing fluoro atom at the
maintenance of the inhibitory activity (data not shown). Thus, para- and meta-positions of the benzene ring were tolerated in
we modified the right-hand side chain moiety (right hand, terms of the inhibitory activity, while ortho-fluoro substitution
RH). The strategy for optimization of RH is summarized in resulted in a slight decrease of the activity (7f–h). Introduction
Fig. 4. From the perspective of feasibility of synthesis, we ini- of the electron-donating methoxy group was associated with a
tially designed a biphenyl derivative, however, its CNS MPO similar tendency (7i–k). In comparison with the fluoro atom
score was lower than that of 6d due to its relatively high lipo- and methoxy group, fluoro-substituted derivatives showed
philicity. Therefore, to modulate the lipophilicity, we designed higher activities at any position (7f vs. i, 7g vs. j); thus, other
phenylpyridine derivatives, which exhibited almost equivalent electron-withdrawing substituents at the para- and meta-posi-
CNS MPO scores to the score of 6d. The results are shown in tions were examined for increasing the activity.
Tables 2 and 3.
Although introduction of a trifluoromethyl group at the
Among phenylpyridine derivatives (7a–c), it was found that para-position resulted in a decrease of the activity as com-
the 2-phenyl-4-pyridyl derivative 7c showed moderate in- pared to a fluoro substitution, meta-trifluoromethyl was as-
hibitory activity. Replacement of the n-propyl with an i-propyl sociated with an increase of the activity (7l: IC50=37 nM, 7m:
group resulted in a slight increase of the inhibitory activity IC50=8.2nM). In the case of the trifluoromethoxy group, both

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Fig. 4. Strategy for Optimization of the RH Moiety
crosomes were evaluated. We found that the para-substituted
derivative 7n exhibited higher microsomal stability (% me-
tabolized after 15min’ incubation with human microsomes,
7n: 5.6%) than the meta-substituted derivatives 7m and o (7m:
25%, 7o: 25%). Furthermore, 7n did not significantly inhibit
the major CYP450 enzymes (3A4, 2D6, 2C9, 2C19, and 1A2)
at a concentration of 10µM. From these results, we selected 7n
for further in vivo evaluation. The results are summarized in
Fig. 5.
Table 3. In Vitro GlyT1 Inhibitory Activity of Compounds 7e–o
No.
Ar2
IC50 (nM)
20
CNS MPO
5.81
7e
The pharmacokinetic (PK) parameters of 7n in rats are
shown in Fig. 5(a). In the intravenous administration, the sys-
temic clearance of 7n was about a half of the hepatic blood
flow, and the oral bioavailability was 42% at the dose of
2.55mg/kg. Furthermore, 7n showed higher maximum plasma
exposure and a higher plasma to brain penetration ratio than 5
(7n (2.55mg/kg): Cmax=0.64µM, Tmax=0.42h, B/P ratio=0.90,
5 (10mg/kg): Cmax=0.24µM, Tmax=4.0h, B/P ratio=0.52).
These PK results prompted us to conduct an in vivo study of
7n using a rat model with measurement of the CSF concentra-
tion of glycine, which is considered to reflect the extracellular
glycine concentration in the brain. As shown in Fig. 5(b),
significant increase of the CSF glycine concentration was ob-
served in a dose-dependent manner from 3mg/kg oral dosing,
indicating that 7n blocked GlyT1 in vivo and may be expected
to exhibit efficacy in rodent models of schizophrenia. The
minimum effective dose (MED) of 7n was 3mg/kg per os
(p.o.), which was almost close efficacy comparing with that
of 5 (1mg/kg p.o.). The slight difference in MED could be
partially explained by the difference in in vitro activity. Detail
PK/pharmacodynamics (PD) studies will be needed for further
comparison of two compounds.
7f
18
16
5.85
5.84
7g
7h
43
5.76
7i
7j
34
37
5.93
5.94
7k
190
5.96
7l
37
5.00
5.00
4.75
4.75
Conclusion
In this article, we have described the identification of 7n
as a structurally diverse back-up compound of 5. Compound
7n exhibited potent GlyT1 inhibitory activity, good meta-
bolic stability, and a favorable PK profile. Furthermore, in vivo
evaluation showed that 7n significantly increased the CSF
glycine concentration in rats following oral dosing at 3mg/
kg. Compound 7n also showed a higher CNS MPO score and
different physicochemical properties as compared to 5 (5: 3.17,
7n: 4.75); thus, 7n could be a suitable back-up candidate to 5.
Further in vivo pharmacological evaluation will be reported in
7m
7n
7o
8.2
7.3
7.9
the para- and meta-substituted analogs showed good inhibito- due course.
ry activities (7n: IC50=7.3 nM, 7o: IC50=7.9 nM). Although both
trifluoromethyl and trifluoromethoxy groups have a relatively
high molecular weight and lipophilicity, these compounds re-
tained high CNS MPO scores of around 5.0.
Experimental
1H- and 13C-NMR spectra were recorded on a JEOL JNM-
ECA600 or JEOL JNM-ECA500, and the chemical shifts
Having obtained potent compounds with structurally novel were expressed in δ (ppm) values with trimethylsilane as an
side chains, the metabolic stabilities of 7m–o in human mi- internal reference (s=singlet, d=doublet, t=triplet, q=quartet,

Vol. 64, No. 11 (2016)
Chem. Pharm. Bull.
1635
Fig. 5. Summary of the Profile of 7n
(a) PK parameters of 7n in rats. (b) Effects of 7n on the CSF glycine levels in rats. Data represent the mean S.E.M. (n=6–7). Vehicle: 0.5% methylcellulose,
***p<0.001, n.s.: not significant (p>=0.05) versus the vehicle-treated group (Dunnett’s test). (c) CNS MPO scores of each component and radar chart based on each
component of CNS MPO.
m=multiplet, and br=broad peak). Some NMR signals dou- CDCl3) δ: 3.73 (3 H, s), 4.62 (2 H, d, J=6.0Hz), 7.08–7.13 (1
bled and broadened due to the existence of rotamers caused H, m), 7.18 (1 H, s), 7.26–7.29 (1 H, m), 7.31–7.37 (2 H, m),
by the sterically hindered amide moiety. MS were recorded 7.44–7.51 (1 H, m), 7.55 (1 H, d, J=1.4Hz); MS ESI: m/z 300
on a micromass Platform LC or Shimadzu LCMS-2010EV. [M+H]+.
High resolution (HR) mass spectral data were acquired using
a Shimadzu LCMS-IT-TOF equipped with an electrospray 1H-imidazole-4-carboxamide (6a) To
N,1-Dimethyl-N-{[3-(trifluoromethoxy)phenyl]methyl}-
solution of
a
9
ionization (ESI)/atmospheric pressure chemical ionization (50mg, 0.17mmol) in N,N-dimethylformamide (1mL) was
dual ion source. The purities of the final compounds were added sodium hydride (60% in oil, 8mg, 0.20mmol), and the
confirmed using LC-MS on an Agilent instrument with ESI. mixture was stirred at room temperature for 10min. To the
The LC-MS conditions were as follows: Agilent 1290 infinity reaction mixture was added methyl iodide (12µL, 0.19mmol),
and Agilent 6150; column Waters Acquity CSH C18, 1.7µm, and the mixture was stirred for an additional 30min. The
2.1mm ×50mm; eluent A, water +0.1% formic acid; eluent B, reaction was quenched with saturated aqueous NaHCO3 solu-
acetonitrile +0.1% formic acid; 20–99% B for 1.2min, 99% tion and extracted with ethyl acetate. The organic layer was
B for 0.2min; flow rate 0.8mL/min; UV detection, λ=254nm. washed with water and brine, dried over anhydrous MgSO4,
1-Methyl-N-{[3-(trifluoromethoxy)phenyl]methyl}-1H- filtered, and concentrated in vacuo. The residue was puri-
imidazole-4-carboxamide (9) To a solution of 1-methyl-1H- fied using silica gel column chromatography (0–2% MeOH
imidazole-4-carboxylic acid (0.50g, 4.0mmol), 1-hydroxy- in CHCl3) to obtain 6a (42mg, 80%) as a colorless powder.
benztriazole monohydrate (0.74g, 4.8mmol), and 1-ethyl-3- 1H-NMR (600MHz, DMSO-d6) δ: 2.83 and 3.38 (3H, brs),
(3-dimethylaminopropyl)carbodiimide hydrochloride (0.92g, 3.69 (3H, s), 4.67 and 5.37 (2H, brs), 7.23–7.32 (3H, m), 7.48
4.8mmol) in acetonitrile (10mL) was added a solution of (1H, t, J=7.8Hz), 7.64 (1H, brs), 7.69–7.72 (1H, m); 13C-NMR
3-(trifluoromethoxy)benzylamine 8 (0.84g, 4.4mmol) in aceto- (151MHz, DMSO-d6) δ: 33.12, 33.46, 36.23, 50.32, 52.21,
nitrile (10mL), and the mixture was stirred at room tempera- 119.38, 119.64, 119.82, 120.03 (q, J=256.7Hz), 126.53, 130.37,
ture for overnight. The reaction mixture was concentrated in 136.84, 137.42, 140.96, 141.54, 148.52, 163.37; HR-MS: Calcd
vacuo, and saturated aqueous NaHCO3 solution was added to for C14H14F3N3O2 [M+H]+ 314.1111. Found 314.1089.
the residue. After extraction with ethyl acetate, the organic
N-Ethyl-1-methyl-N-{[3-(trifluoromethoxy)phenyl]-
layer was dried over anhydrous MgSO4, filtered, and con- methyl}-1H-imidazole-4-carboxamide (6b) Compound 6b
centrated in vacuo. The residue was purified using silica gel (73%, colorless powder) was obtained in a similar manner
1
column chromatography (0–10% MeOH in CHCl3) to obtain to that described for 6a. H-NMR (600MHz, DMSO-d6) δ:
9 (1.18g, 98%) as a colorless powder. 1H-NMR (600MHz, 0.99–1.18 (3H, m), 3.29 and 3.92 (2H, brs), 3.69 (3H, s), 4.67

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Chem. Pharm. Bull.
Vol. 64, No. 11 (2016)
and 5.37 (2H, brs), 7.23–7.31 (2H, m), 7.33 (1H, d, J=7.8Hz), DMSO-d6) δ: 1.02–1.15 (6H, m), 3.69 (3H, brs), 4.44–4.71 and
7.47 (1H, t, J=7.9Hz), 7.61–7.69 (1H, m), 7.71 (1H, s); 5.21–5.40 and 5.54–5.67 (3H, m), 7.18 (1H, brd, J=8.3Hz),
13C-NMR (151MHz, DMSO-d6) δ: 12.32, 14.39, 33.10, 40.45, 7.22 (1H, brs), 7.31 (1H, d, J=7.8Hz), 7.42 (1H, s), 7.54–7.72
42.54, 47.81, 49.68, 119.26, 119.78, 120.04 (q, J=259.72Hz), (2H, m); 13C-NMR (151MHz, DMSO-d6) δ: 19.89, 21.16,
126.43, 130.21, 137.06, 137.51, 141.79, 142.05, 148.46, 162.73, 33.08, 42.91, 46.68, 48.17, 118.65, 119.20, 120.02 (q, J=258.21),
163.27; HR-MS: Calcd for C15H16F3N3O2 [M+H]+ 328.1267. 125.79, 125.93, 126.51, 126.69, 129.85, 137.34, 143.39, 148.28,
Found 328.1261.
1-Methyl-N-propyl-N-{[3-(trifluoromethoxy)phenyl]- 342.1424. Found 342.1398.
156.52, 163.85; HR-MS: Calcd for C16H18F3N3O2 [M+H]+
methyl}-1H-imidazole-4-carboxamide (6c) Compound 6c
N-Cyclohexyl-1-methyl-N-{[3-(trifluoromethoxy)phenyl]-
(73%, colorless oil) was obtained in a similar manner to methyl}-1H-imidazole-4-carboxamide (6f) Compound 6f
that described for 6a. 1H-NMR (600MHz, DMSO-d6) δ: (9%, colorless powder) was obtained from 10b in a similar
1
0.73–0.84 (3H, m), 1.45–1.62 (2H, m), 3.22 and 3.87 (2H, brs), manner to that described for 9. H-NMR (600MHz, DMSO-
3.70 (3H, s) 4.68 and 5.39 (2H, brs), 7.23–7.34 (3H, m), 7.46 d6) δ: 0.96–1.09 (1H, m), 1.13–1.59 (6H, m), 1.61–1.73 (3H, m),
(1H, t, J=8.0Hz), 7.59–7.68 (1H, m), 7.70 (1H, s); 13C-NMR 3.70 (3H, brs), 4.12–4.32 and 4.54–4.76 and 5.06–5.46 (3H, m),
(151MHz, DMSO-d6) δ: 10.75, 11.13, 20.04, 21.86, 33.10, 47.31, 7.17 (1H, d, J=8.3Hz), 7.20 (1H, s), 7.29 (1H, brd, J=7.4Hz),
48.31, 49.28, 50.16, 119.26, 119.74, 120.04 (q, J=255.19Hz), 7.38–7.44 (1H, m), 7.48–7.72 (2H, m); 13C-NMR (151MHz,
126.39, 126.63, 127.20, 130.21, 137.04, 137.44, 139.35, 141.69, DMSO-d6) δ: 24.72, 25.44, 30.02, 31.41, 33.08, 43.95, 46.79,
142.05, 148.46, 163.39; HR-MS: Calcd for C16H18F3N3O2 54.78, 56.31, 118.57, 119.12, 119.94, 120.01 (q, J=256.7Hz),
[M+H]+ 342.1424. Found 342.1404.
125.75, 126.03, 126.63, 129.79, 130.15, 137.34, 137.67, 143.41,
1-Methyl-N-(2-methylpropyl)-N-{[3-(trifluoromethoxy)- 144.04, 148.24, 148.42, 163.27, 164.05; HR-MS: Calcd for
phenyl]methyl}-1H-imidazole-4-carboxamide (6e) Com- C19H22F3N3O2 [M+H]+ 382.1737. Found 382.1716.
pound 6e (40%, colorless oil) was obtained in a similar man-
1-Methyl-N-(oxan-4-yl)-N-{[3-(trifluoromethoxy)phenyl]-
1
ner to that described for 6a. H-NMR (499MHz, CDCl3) δ: methyl}-1H-imidazole-4-carboxamide (6g) Compound 6g
0.82–0.98 (6H, m), 1.94–2.13 (1H, m), 3.21–3.28 and 3.88–3.98 (14%, colorless powder) was obtained from 10c in a similar
1
(2H, m), 3.71 (3H, brs), 4.76 and 5.43 (2H, brs), 7.05–7.24 manner to that described for 9. H-NMR (600MHz, CDCl3)
(3H, m), 7.29–7.35 (1H, m), 7.35–7.43 (1H, m), 7.57 (1H, d, δ: 1.56–1.82 (4H, m), 3.45 (2H, brt, J=11.8Hz), 3.71 (3H, brs),
J=1.4Hz); 13C-NMR (126MHz, CDCl3) δ: 19.90, 20.27, 26.71, 3.95 (2H, brdd, J=11.6, 4.1Hz), 4.60–4.86 and 5.28–5.66 (3H,
33.68, 51.58, 53.13, 119.41, 120.01, 126.37, 129.80, 136.47, m), 7.05 (1H, brd, J=7.8Hz), 7.12 (1H, brs), 7.18–7.23 (1H, m),
149.46, 164.04; HR-MS: Calcd for C17H20F3N3O2 [M+H]+ 7.26–7.46 (1H, m), 7.36–7.40 (1H, m), 7.57 (1H, brs); 13C-NMR
356.1580. Found 356.1551.
(151MHz, DMSO-d6) δ: 30.62, 32.06, 33.57, 44.98, 47.46,
N-{[3-(Trifluoromethoxy)phenyl]methyl}propan-2-amine 52.54, 54.19, 67.47, 119.00, 119.53, 120.43 (q, J=259.7Hz),
(10a) To a solution of acetone (0.38mL, 5.2mmol) and 8 125.13, 126.48, 129.55, 136.63, 138.40, 142.18, 142.94, 149.31,
(1.0g, 5.2mmol) in CHCl3 (10mL) was added sodium triace- 164.58; HR-MS: Calcd for C18H20F3N3O3 [M+H]+ 384.1530.
toxyborohydride (2.2g, 10mmol), and the mixture was stirred Found 384.1507.
at room temperature for 45min. The mixture was quenched
N-[(6-Bromopyridin-2-yl)methyl]propan-1-amine (12a)
with saturated aqueous NaHCO3 solution and extracted with Compound 12a (99%, yellow oil) was obtained from 2-bro-
CHCl3. The organic layer was washed with brine, dried over mopyridine-6-carboxaldehyde 11 and 1-aminopropane in a
1
anhydrous Na2SO4, filtered, and concentrated in vacuo. The similar manner to that described for 10a. H-NMR (600MHz,
residue was purified with silica gel column chromatogra- CDCl3) δ: 0.94 (3H, t, J=7.3Hz), 1.52–1.59 (2H, m), 2.59–2.64
phy (0–10% MeOH in CHCl3) to obtain 10a (0.68g, 56%) as (2H, m), 3.89 (2H, s), 7.29 (1H, d, J=7.4Hz), 7.36 (1H, d,
1
a colorless oil. H-NMR (600MHz, CDCl3) δ: 1.10 (6H, d, J=7.8Hz), 7.51 (1H, t, J=7.5Hz); MS (ESI): m/z 229 [M+H]+.
J=6.4Hz), 2.84 (1H, spt, J=6.3Hz), 3.80 (2H, s), 7.09 (1H, d,
J=7.3Hz), 7.20 (1H, s), 7.30–7.36 (1H, m); MS (ESI): m/z 234 Compound 12b (49%, pale yellow oil) was obtained from 11
[M+H]+.
and 2-aminopropane in a similar manner to that described for
N-[(6-Bromopyridin-2-yl)methyl]propan-2-amine (12b)
1
N-{[3-(Trifluoromethoxy)phenyl]methyl}cyclohexanamine 10a. H-NMR (600MHz, CDCl3) δ: 1.11 (6H, d, J=6.0Hz),
(10b) Compound 10b (quant., colorless oil) was obtained in a 2.84 (1H, spt, J=6.3Hz), 3.88 (2H, s), 7.29 (1H, d, J=7.3Hz),
1
similar manner to that described for 10a. H-NMR (600MHz, 7.33–7.36 (1H, m), 7.49 (1H, t, J=7.6Hz); MS (ESI): m/z 229
CDCl3) δ: 1.08–1.27 (4H, m), 1.56–1.66 (2H, m), 1.67–1.80 [M+H]+.
(2H, m), 1.82–1.99 (2H, m), 2.43–2.51 (1H, m), 3.83 (2H, s),
7.07–7.12 (1H, m), 7.20–7.28 (2H, m), 7.30–7.38 (1H, m); MS imidazole-4-carboxamide (13a) Compound 13a (67%, pale
(ESI): m/z 274 [M+H]+.
yellow oil) was obtained from 12a in a similar manner to that
N-[(6-Bromopyridin-2-yl)methyl]-1-methyl-N-propyl-1H-
1
N-{[3-(Trifluoromethoxy)phenyl]methyl}oxan-4-amine described for 9. H-NMR (600MHz, CDCl3) δ: 0.83–0.93 (3H,
(10c) Compound 10c (82%, colorless oil) was obtained in a m), 1.61–1.71 (2H, m), 3.34–4.05 (5H, m), 4.72–5.51 (2H, m),
1
similar manner to that described for 10a. H-NMR (600MHz, 7.29–8.11 (5H, m); MS (ESI): m/z 337 [M+H]+.
CDCl3) δ: 1.40–1.49 (2H, m) 1.82–1.89 (2H, m) 2.66–2.76 (1H,
m) 3.36–3.44 (2H, m) 3.85 (2H, s) 3.94–4.02 (2H, m) 7.08–7.38 2-yl)-1H-imidazole-4-carboxamide (13b) Compound 13b
(4H, m); MS (ESI): m/z 276 [M+H]+.
(95%, colorless powder) was obtained from 12b in a similar
N-[(6-Bromopyridin-2-yl)methyl]-1-methyl-N-(propan-
1
1-Methyl-N-(propan-2-yl)-N-{[3-(trifluoromethoxy)- manner to that described for 9. H-NMR (600MHz, CDCl3) δ:
phenyl]methyl}-1H-imidazole-4-carboxamide (6d) Com- 1.09–1.24 (6H, m), 3.64–3.76 (3H, m), 4.70–4.88 and 5.29–5.36
pound 6d (93%, colorless powder) was obtained from 10a in and 5.68–5.75 (3H, m), 7.26–7.34 (2H, m), 7.41–7.47 (2H, m),
1
a similar manner to that described for 9. H-NMR (600MHz, 7.51–7.59 (1H, m); MS (ESI): m/z 337 [M+H]+.

Vol. 64, No. 11 (2016)
Chem. Pharm. Bull.
1637
N-[(2-Bromopyridin-4-yl)methyl]propan-1-amine (15a) 7.95 (2H, brd, J=6.9Hz), 8.61 (1H, d, J=4.8Hz); 13C-NMR
Compound 15a (37%, pale yellow oil) was obtained from (126MHz, CDCl3) δ: 11.01, 11.42, 20.54, 22.28, 33.59, 48.49,
2-bromopyridine-4-carboxaldehyde 14 and 1-aminopropane 49.06, 50.13, 51.06, 119.06, 119.41, 120.76, 120.98, 126.50,
in a similar manner to that described for 10a. 1H-NMR 127.01, 128.66, 128.91, 136.65, 138.32, 139.33, 148.15, 148.96,
(600MHz, CDCl3) δ: 0.94 (1H, t, J=7.3Hz), 1.50–1.55 (2H, 149.74, 157.69, 163.87, 164.32; HR-MS: Calcd for C20H22N4O
m), 2.57 (2H, t, J=7.3Hz), 3.79 (2H, s), 7.23 (1H, dd, J=5.0, [M+H]+ 335.1866. Found 335.1856.
1.4Hz), 7.49–7.50 (1H, m), 8.29 (1H, d, J=5.0Hz); MS (ESI):
1-Methyl-N-[(6-phenylpyridin-2-yl)methyl]-N-(propan-
2-yl)-1H-imidazole-4-carboxamide (7d) Compound 7d
m/z 229 [M+H]+.
N-[(2-Bromopyridin-4-yl)methyl]propan-2-amine (15b) (52%, colorless oil) was obtained from 13b in a similar man-
Compound 15b (74%, pale yellow oil) was obtained from 14 ner to that described for 7a. H-NMR (499MHz, CDCl3) δ:
1
and 2-aminopropane in a similar manner to that described for 1.14–1.30 (6H, m), 3.65 and 3.73 (3H, brs), 4.86 (2H, brs),
1
10a. H-NMR (600MHz, CDCl3) δ: 1.09 (6 H, d, J=6.4Hz), 5.43 and 5.72 (1H, brs), 7.28 (1H, brd, J=7.5 Hz), 7.37–7.49
2.83 (1 H, spt, J=6.3Hz), 3.78 (2 H, s), 7.23 (1 H, dd, J=5.0, (4H, m), 7.53–7.57 (2H, m), 7.62–7.67 (1H, m), 8.00 (2H, d,
0.9Hz), 7.50–7.51 (1 H, m), 8.28 (1 H, d, J=5.0Hz); MS (ESI): J=7.5Hz); 13C-NMR (126MHz, CDCl3) δ: 20.23, 21.50, 33.57,
m/z 229 [M+H]+.
46.88, 47.26, 48.97, 49.99, 118.37, 119.77, 120.03, 125.86,
N-[(2-Bromopyridin-4-yl)methyl]-1-methyl-N-propyl-1H- 126.98, 128.43, 128.53, 128.64, 129.47, 131.91, 131.93, 132.05,
imidazole-4-carboxamide (16a) Compound 16a (81%, pale 132.13, 136.57, 136.83, 137.11, 156.41, 159.28, 164.48; HR-MS:
yellow oil) was obtained from 15a in a similar manner to that Calcd for C20H22N4O [M+H]+ 335.1866. Found 335.1855.
1
described for 9. H-NMR (600MHz, CDCl3) δ: 0.84–0.97 (3H,
1-Methyl-N-[(2-phenylpyridin-4-yl)methyl]-N-(propan-
m), 1.59–1.73 (2H, m), 3.29–4.04 (5H, m), 4.60–4.73 (1H, m), 2-yl)-1H-imidazole-4-carboxamide (7e) Compound 7e
5.30–5.50 (1H, m), 7.12–7.64 (4H, m), 8.28 (1H, d, J=5.0Hz); (58%, colorless amorphous) was obtained from 16b in a
1
MS (ESI): m/z 337 [M+H]+.
similar manner to that described for 7a. H-NMR (499MHz,
N-[(2-Bromopyridin-4-yl)methyl]-1-methyl-N-(propan- CDCl3) δ: 1.14–1.30 (6H, m), 3.66 and 3.72 (3H, brs), 4.69
2-yl)-1H-imidazole-4-carboxamide (16b) Compound 16b and 5.37 (2H, brs), 4.78–4.94 and 5.74–5.86 (1H, m), 7.14–7.25
(98%, pale yellow oil) was obtained from 15b in a similar (1H, m), 7.35–7.49 (4H, m), 7.56–7.59 (1H, m), 7.64 (1H, brs),
1
manner to that described for 9. H-NMR (600MHz, CDCl3) δ: 7.94 (2H, brd, J=7.5Hz), 8.57 (1H, brd, J=4.5Hz); 13C-NMR
1.14–1.23 (6H, m), 3.62–3.77 (3H, m), 4.49–4.90 and 5.22–5.34 (126MHz, CDCl3) δ: 20.37, 21.61, 33.60, 43.88, 46.98, 47.27,
and 5.75–5.84 (3H, m), 7.17 (1H, brs), 7.27–7.31 (1H, m), 48.85, 109.90, 118.88, 120.51, 126.36, 127.01, 128.64, 128.81,
7.37–7.45 (2H, m), 7.57 (1H, brs), 8.24 (1H, brd, J=5.0Hz); 136.64, 138.37, 139.53, 149.51, 149.74, 150.96, 157.43, 164.48;
MS (ESI): m/z 337 [M+H]+.
HR-MS: Calcd for C20H22N4O [M+H]+ 335.1866. Found
1-Methyl-N-[(6-phenylpyridin-2-yl)methyl]-N-propyl-1H- 335.1851.
imidazole-4-carboxamide (7a) To solution of 13a N-{[2-(4-Fluorophenyl)pyridin-4-yl]methyl}-1-methyl-N-
a
(150mg, 0.44mmol) in N,N-dimethylformamide (2mL) and (propan-2-yl)-1H-imidazole-4-carboxamide Bishydrochlo-
ethanol (1mL) were added phenylboronic acid (107mg, ride (7f) To a solution of 16b (1.50g, 4.4mmol) in N,N-
0.88mmol), potassium carbonate (122mg, 0.88mmol), and dimethylformamide (10mL) and ethanol (5mL) were added
tetrakis(triphenylphosphine)palladium(0) (51mg, 0.044mmol), 4-fluorophenylboronic acid (1.24g, 8.9mmol), potassium
and the reaction mixture was stirred at 150°C under micro- carbonate (1.23g, 8.9mmol), and tetrakis(triphenylphosphine)-
wave irradiation for 10min. Water was added, and the mix- palladium(0) (0.51g, 0.45mmol), and the reaction mixture was
ture was extracted with ethyl acetate. The organic layer was stirred at 150°C under microwave irradiation for 30min. Water
washed with water and brine, dried over anhydrous MgSO4, was added, and the mixture was extracted with CHCl3. The
filtered, and concentrated in vacuo. The residue was purified organic layer was dried over anhydrous MgSO4, filtered, and
using silica gel column chromatography (0–5% MeOH in concentrated in vacuo. The residue was purified using NH-
CHCl3) and NH-silica gel column chromatography (67–100% silica gel column chromatography (25–100% ethyl acetate in
ethyl acetate in hexane) to obtain 7a (98mg, 67%) as a color- hexane) and silica gel column chromatography (0–10% MeOH
less oil. 1H-NMR (499MHz, CDCl3) δ: 0.84–0.95 (3H, m), in CHCl3). The fractions including the product were collected
1.64–1.82 (2H, m), 3.46 (1H, brt, J=7.4Hz), 3.68 and 3.72 and concentrated in vacuo. The residue was dissolved in ethyl
(3H, brs), 4.07 (1H, brt, J=7.2Hz), 4.93 (1H, brs), 5.53 (1H, acetate (10mL), and 4mol/L HCl in ethyl acetate (1.9mL)
s), 7.23–7.33 (2H, m), 7.38–7.49 (3H, m), 7.56–7.61 (2H, m), was added to the solution. After stirring at room temperature
7.68 (1H, t, J=7.7Hz), 7.98–8.03 (2H, m); 13C-NMR (126MHz, for 4.5h, the resultant precipitate was collected by filtration
CDCl3) δ: 11.04, 11.45, 20.49, 22.24, 33.54, 48.56, 50.40, 52.01, to obtain 7f (1.41g, 79%) as a colorless powder. 1H-NMR
53.99, 118.65, 118.72, 119.71, 120.09, 125.90, 126.05, 126.95, (600MHz, DMSO-d6) δ: 1.11–1.31 (6H, m), 3.75 and 3.92 (3H,
128.67, 128.77, 128.87, 136.58, 137.27, 138.61, 139.33, 139.51, brs), 4.61 and 4.89 and 5.12 (3H, brs), 7.46 (2H, t, J=8.7Hz),
156.69, 158.14, 158.84, 164.20; HR-MS: Calcd for C20H22N4O 7.73 (1H, brs), 8.18–8.28 (4H, m), 8.72 (1H, d, J=5.8Hz), 9.20
[M+H]+ 335.1866. Found 335.1855.
(1H, brs); 13C-NMR (151MHz, DMSO-d6) δ: 20.90, 35.57,
1-Methyl-N-[(2-phenylpyridin-4-yl)methyl]-N-pro- 44.09, 49.94, 116.14, 116.28, 121.37, 122.23, 124.02, 126.61,
pyl-1H-imidazole-4-carboxamide (7c) Compound 7c (74%, 129.61, 130.57, 137.10, 144.08, 151.33, 156.70, 159.43, 163.05,
colorless oil) was obtained from 16a in a similar manner 164.70; HR-MS: Calcd for C20H21FN4O [M+H]+ 353.1772.
to that described for 7a. 1H-NMR (499MHz, CDCl3) δ: Found 353.1784.
0.83–0.98 (3H, m), 1.63–1.76 (2H, m), 3.41 (1H, brs), 3.69
and 3.72 (3H, brs), 3.99 (1H, brs), 4.79 (1H, brs), 5.49 (1H, (propan-2-yl)-1H-imidazole-4-carboxamide
brs), 7.09–7.20 (1H, m), 7.28–7.48 (4H, m), 7.57–7.66 (2H, m), pound 7g (49%, colorless amorphous) was obtained from
N-{[2-(3-Fluorophenyl)pyridin-4-yl]methyl}-1-methyl-N-
(7g) Com-

1638
Chem. Pharm. Bull.
Vol. 64, No. 11 (2016)
1
16b in a similar manner to that described for 7a. H-NMR
N-{[2-(2-Methoxyphenyl)pyridin-4-yl]methyl}-1-meth-
(499MHz, CDCl3) δ: 1.14–1.30 (6H, m), 3.68 and 3.73 (3H, yl-N-(propan-2-yl)-1H-imidazole-4-carboxamide Bishydro-
brs), 4.61–4.92 and 5.24–5.46 and 5.81 (3H, m), 7.08 (1H, td, chloride (7k) Compound 7k (86%, colorless powder) was
J=8.2, 2.4Hz), 7.20 (1H, brs), 7.33–7.50 (2H, m), 7.55–7.65 obtained from 16b in a similar manner to that described for
1
(2H, m), 7.65–7.74 (2H, m), 8.57 (1H, brd, J=4.8Hz); 7h. H-NMR (600MHz, DMSO-d6) δ: 1.15–1.30 (6H, m), 3.85
13C-NMR (126MHz, CDCl3) δ: 20.40, 21.61, 33.62, 43.85, (3H, s), 3.92 (3H, brs), 4.64 and 4.96 (3H, brs), 7.20 (1H, t,
46.98, 47.32, 48.89, 113.86, 114.04, 115.55, 115.73, 118.94, J=7.4Hz), 7.30 (1H, d, J=8.3Hz), 7.61–7.73 (2H, m), 7.96 (1H,
121.06, 122.54, 126.41, 128.44, 128.54, 130.06, 130.13, 136.67, brs), 8.12 (1H, s), 8.26 (1H, brs), 8.83 (1H, d, J=5.8Hz), 9.19
141.79, 149.57, 156.03, 162.27, 164.21; HR-MS: Calcd for (1H, brs); 13C-NMR (151MHz, DMSO-d6) δ: 20.84, 35.55,
C20H21FN4O [M+H]+ 353.1772. Found 353.1784.
44.29, 49.92, 56.01, 112.34, 119.86, 121.01, 122.97, 124.18,
N-{[2-(2-Fluorophenyl)pyridin-4-yl]methyl}-1-methyl-N- 125.25, 126.59, 131.28, 133.49, 137.18, 141.34, 148.94, 159.15,
(propan-2-yl)-1H-imidazole-4-carboxamide Bishydrochlo- 159.45; HR-MS: Calcd for C21H24N4O2 [M+H]+ 365.1972.
ride (7h) To a solution of 16b (150mg, 0.44mmol) in tolu- Found 365.1962.
ene (1.5mL), ethanol (1.5mL), and water (1.0mL) were added
1-Methyl-N-(propan-2-yl)-N-({2-[4-(trifluoromethyl)-
2-fluorophenylboronic acid (93mg, 0.66mmol), cesium car- phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide
bonate (217mg, 0.67mmol), and tetrakis(triphenylphosphine)- Bishydrochloride (7l) Compound 7l (98%, colorless amor-
palladium(0) (26mg, 0.022mmol), and the reaction mixture phous) was obtained from 16b in a similar manner to that
1
was stirred at 150°C under microwave irradiation for 30min. described for 7f. H-NMR (600MHz, DMSO-d6) δ: 1.15–1.30
Water was added, and the mixture was extracted with ethyl (6H, m), 3.75 and 3.92 (3H, brs), 4.62 and 4.83 and 5.04 (3H,
acetate. The organic layer was dried over anhydrous MgSO4, brs), 7.55 (1H, brs), 7.92 (2H, m, J=8.3Hz), 8.11 (1H, s), 8.26
filtered, and concentrated in vacuo. The residue was purified (1H, brs), 8.32 (2H, m, J=8.3Hz), 8.72 (1H, d, J=5.4Hz), 9.20
using silica gel column chromatography (0–10% MeOH in (1H, brs); 13C-NMR (151MHz, DMSO-d6) δ: 20.96, 35.57,
CHCl3). The fractions including the product were collected 43.81, 49.90, 120.32, 122.15, 123.92, 124.13 (q, J=247.8Hz),
and concentrated in vacuo. The residue was dissolved in 125.79, 126.67, 128.02, 129.73, 129.95, 137.10, 140.24, 147.49,
MeOH (2mL), and 2mol/L HCl in MeOH (0.8mL) was added 152.90, 159.29; HR-MS: Calcd for C21H21F3N4O [M+H]+
to the solution. The solution was concentrated in vacuo to 403.1740. Found 403.1743.
1
obtain 7h (165mg, 87%) as a colorless amorphous. H-NMR
1-Methyl-N-(propan-2-yl)-N-({2-[3-(trifluoromethyl)-
(600MHz, DMSO-d6) δ: 1.21–1.30 (6H, m), 3.92 (3H, brs), phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide
4.54–4.69 and 4.87–5.19 (3H, m), 7.42–7.50 (2H, m), 7.63–7.70 Bishydrochloride (7m) Compound 7m (81%, colorless
(1H, m), 7.81–7.98 (2H, m), 8.05 (1H, brs), 8.22–8.37 (1H, amorphous) was obtained from 16b in a similar manner to
m), 8.83 (1H, d, J=5.8Hz), 9.06–9.35 (1H, m); 13C-NMR that described for 7h. 1H-NMR (600MHz, DMSO-d6) δ:
(151MHz, DMSO-d6) δ: 20.88, 35.65, 44.11, 48.53, 50.00, 1.17–1.30 (6H, m), 3.76 and 3.93 (3H, brs), 4.59 and 4.87
116.42, 116.58, 123.02, 123.96, 124.42, 125.11, 126.11, 128.72, and 5.06 (3H, brs), 7.63 (1H, brs), 7.80–7.86 (1H, m), 7.92
128.80, 131.50, 132.04, 133.16, 137.14, 144.40, 148.02, 158.53, (1H, brd, J=7.4Hz), 8.23 (1H, s), 8.28 (1H, brs), 8.43 (1H, d,
159.19, 160.20; HR-MS: Calcd for C20H21FN4O [M+H]+ J=8.3Hz), 8.47 (1H, s), 8.73 (1H, d, J=5.4Hz), 9.26 (1H, brs);
353.1772. Found 353.1784.
13C-NMR (151MHz, DMSO-d6) δ: 20.94, 35.63, 43.83, 49.98,
N-{[2-(4-Methoxyphenyl)pyridin-4-yl]methyl}-1-meth- 120.84, 122.24 (q, J=273.3Hz), 122.25, 123.86, 124.00, 126.37,
yl-N-(propan-2-yl)-1H-imidazole-4-carboxamide Bishydro- 126.75, 127.01, 129.76 (q, J=30.2Hz), 130.21, 131.42, 136.32,
chloride (7i) Compound 7i (73%, colorless powder) was 137.08, 146.43, 152.00, 153.94, 159.23; HR-MS: Calcd for
obtained from 16b in a similar manner to that described for C21H21F3N4O [M+H]+ 403.1740. Found 403.1742.
7h. 1H-NMR (600MHz, DMSO-d6) δ: 1.07–1.24 (6H, m),
1-Methyl-N-(propan-2-yl)-N-({2-[4-(trifluoromethoxy)-
3.66–3.81 (3H, m), 3.83 (3H, s), 4.73 (2H, brs), 5.26 (1H, brs), phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide
7.08–7.12 (2H, m), 7.34 (1H, brd, J=5.4Hz), 7.74–7.90 (1H, m), Bishydrochloride (7n) Compound 7n (95%, colorless amor-
7.93 (1H, s), 8.03 (2H, brd, J=8.7Hz), 8.27 (1H, brs), 8.57 (1H, phous) was obtained from 16b in a similar manner to that
1
d, J=5.4Hz); 13C-NMR (151MHz, DMSO-d6) δ: 19.79, 21.08, described for 7f. H-NMR (600MHz, DMSO-d6) δ: 1.14–1.30
34.08, 43.55, 48.88, 55.37, 114.43, 119.00, 120.62, 125.35, (6H, m), 3.76 and 3.93 (3H, brs), 4.60 and 4.87 and 5.08 (3H,
128.20, 128.60, 137.38, 146.41, 153.72, 160.92, 162.10; HR-MS: brs), 7.59 (2H, brd, J=8.3Hz), 7.68 (1H, brs), 8.15 (1H, s),
Calcd for C21H24N4O2 [M+H]+ 365.1972. Found 365.1961.
8.23–8.29 (3H, m), 8.73 (1H, d, J=5.4Hz), 9.23 (1H, brs);
N-{[2-(3-Methoxyphenyl)pyridin-4-yl]methyl}-1-meth- 13C-NMR (151MHz, DMSO-d6) δ: 20.94, 35.61, 43.97, 49.94,
yl-N-(propan-2-yl)-1H-imidazole-4-carboxamide Bishydro- 119.16, 120.88, 120.97, 121.37, 122.27, 123.94, 126.51, 129.91,
chloride (7j) Compound 7j (59%, colorless powder) was 137.10, 145.46, 149.89, 151.79, 159.31; HR-MS: Calcd for
obtained from 16b in a similar manner to that described for C21H21F3N4O2 [M+H]+ 419.1689. Found 419.1690.
7h. 1H-NMR (600MHz, DMSO-d6) δ: 1.10–1.30 (6H, m),
1-Methyl-N-(propan-2-yl)-N-({2-[3-(trifluoromethoxy)-
3.66–3.93 (3H, m), 3.88 (3H, s), 4.64–5.21 (3H, m), 7.12–7.18 phenyl]pyridin-4-yl}methyl)-1H-imidazole-4-carboxamide
(1H, m), 7.51 (1H, t, J=7.8Hz), 7.58–7.68 (2H, m), 7.70–7.75 Bishydrochloride (7o) Compound 7o (60%, colorless amor-
(1H, m), 8.16 (2H, s), 8.70 (1H, d, J=5.8Hz), 8.98 (1H, brs); phous) was obtained from 16b in a similar manner to that
1
13C-NMR (151MHz, DMSO-d6) δ: 19.69, 20.94, 35.19, 43.91, described for 7h. H-NMR (600MHz, DMSO-d6) δ: 1.15–1.30
49.64, 55.43, 112.73, 116.70, 119.82, 121.03, 122.01, 124.36, (6H, m), 3.77 and 3.93 (3H, brs), 4.61 and 4.86 and 5.02 (3H,
126.33, 130.29, 135.42, 137.20, 144.92, 152.56, 159.73, 160.07; brs), 7.51–7.66 (2H, m), 7.73 (1H, t, J=8.1Hz), 8.12 (1H, s),
HR-MS: Calcd for C21H24N4O2 [M+H]+ 365.1972. Found 8.15–8.18 (2H, m), 8.27 (1H, brs), 8.72 (1H, d, J=5.8Hz), 9.25
365.1959.
(1H, brs); 13C-NMR (151MHz, DMSO-d6) δ: 20.94, 35.63,

Vol. 64, No. 11 (2016)
Chem. Pharm. Bull.
1639
43.87, 49.96, 119.84, 120.10 (q, J=258.2Hz), 120.72, 122.25, acted at room temperature for 15min. After the completion of
122.61, 123.86, 126.49, 131.13, 137.10, 137.59, 146.43, 148.88, the reaction, the labeled glycine solution was aspirated with
151.88, 154.01, 159.19; HR-MS: Calcd for C21H21F3N4O2 a manifold. The cells were then lysed with 0.5mol/L sodium
[M+H]+ 419.1689. Found 419.1691.
hydroxide solution. The amount of intracellular glycine was
4-Bromo-N-propylpyridine-2-carboxamide (18) Com- determined by measuring the radio activity in the cell lysate
pound 18 (84%, colorless oil) was obtained from 4-bromo- using a liquid scintillation counter. The quantity of glycine
pyridine-2-carboxylic acid 17 and 1-aminopropane in a similar uptake in the presence of 10µM (N-[3-(4′-fluorophenyl)-3-(4′-
1
manner to that described for 9. H-NMR (600MHz, CDCl3) δ: phenylphenoxy)propyl])sarcosine (ALX5407) was defined as
1.00 (3H, t, J=7.3Hz), 1.62–1.69 (2H, m), 3.41–3.46 (2H, m), nonspecific uptake, and the specific uptake amount was deter-
7.57–7.60 (1H, m), 7.92–8.01 (1H, m), 8.35 (1H, d, J=5.0Hz), mined by subtracting the nonspecific uptake amount from the
8.38 (1H, d, J=1.8Hz); MS (ESI): m/z 243 [M+H]+.
total uptake amount in the absence of 10µM ALX5407. The
4-Phenyl-N-propylpyridine-2-carboxamide (19) Com- glycine uptake inhibitory activity (IC50 value) was calculated
pound 19 (88%, pale yellow oil) was obtained from 18 in a from an inhibition curve for test compound concentrations of
1
similar manner to that described for 7a. H-NMR (600MHz, 10−9 to 10−5.
CDCl3) δ: 1.02 (3H, t, J=7.3Hz), 1.65–1.72 (2H, m), 3.43–3.51
Measurement of Glycine Concentration in CSF of Rats
Rats were anesthetized by isoflurane 1h after oral ad-
(2H, m), 7.28–8.60 (9H, m); MS (ESI): m/z 241 [M+H]+.
N-[(4-Phenylpyridin-2-yl)methyl]propan-1-amine
(20) ministration of vehicle or 7n, and were sacrificed by cutting
To a solution of 19 (0.35g, 1.5mmol) in tetrahydrofuran of an abdominal aorta. Then, CSF samples were collected
(10mL) was added lithium aluminium hydride (0.28g, from the cisterna magna using a 29-gauge needle. The CSF
7.3mmol), and the mixture was stirred at 70°C for 2h. The samples were centrifuged at 21500×g for 10min at 4°C. The
reaction was quenched with 10% aqueous NaOH solution glycine standard and the CSF samples were derivatized with
under ice cooling, dried over anhydrous MgSO4, filtered, and 1.33 mM of o-phthaldialdehyde at 10°C for 2.5min, then in-
concentrated in vacuo. The residue was purified using NH- jected into a high-performance liquid chromatography device
silica gel column chromatography (50–100% ethyl acetate in equipped with an electrochemical detection system, ECD-300
1
hexane) to obtain 20 (107mg, 32%) as a yellow oil. H-NMR (Eicom, Kyoto, Japan). Derivatized glycine was separated on
(600MHz, CDCl3) δ: 0.95 (3H, t, J=7.6Hz), 1.53–1.62 (2H, m), a reversed phase Octa-Decyl-Silyl (ODS) column, Eicompak
2.65–2.69 (2H, m), 3.97 (2H, s), 7.38 (1H, dd, J=5.0, 1.8Hz), SC-5ODS (3.0mm, i.d.×150mm, Eicom, Kyoto, Japan), at
7.42–7.46 (1H, m), 7.46–7.51 (2H, m), 7.54 (1H, s), 7.63–7.67 35°C with a flow rate of 0.5mL/min. The electrode potential
(2H, m), 8.60 (1H, d, J=5.0Hz); MS (ESI): m/z 227 [M+H]+.
for the electrochemical detector was set at +600mV against
1-Methyl-N-[(4-phenylpyridin-2-yl)methyl]-N-propyl-1H- Ag/AgCl reference electrode. The mobile phase consisted of
imidazole-4-carboxamide (7b) Compound 7b (28%, color- 0.1 M phosphate buffer solution (pH 6.0) containing 10.0%
less oil) was obtained in a similar manner to that described v/v acetonitrile and 5.0mg/L ethylenediaminetetraacetic acid
for 9. 1H-NMR (499MHz, CDCl3) δ: 0.83–0.95 (3H, m), disodium salt.
1.64–1.75 (2H, m), 3.45 (1H, brt, J=7.4Hz), 3.68 and 3.71
All the studies were reviewed by the Taisho Pharmaceutical
(3H, brs), 4.04 (1H, brt, J=6.9Hz), 4.92 (1H, brs), 5.55 (1H, Co., Ltd., Animal Care Committee.
brs), 7.28–7.47 (5H, m), 7.54–7.63 (4H, m), 8.58 (1H, brd,
J=4.8Hz); 13C-NMR (126MHz, CDCl3) δ: 11.01, 11.44, 20.45,
Acknowledgments The authors would like to thank Dr.
22.22, 33.55, 48.55, 50.26, 51.77, 53.85, 119.34, 119.92, 120.09, Shigeyuki Chaki for helpful discussion: Dr. Takashi Yoshi-
120.22, 126.21, 127.07, 127.16, 129.00, 136.62, 138.31, 138.48, zumi for carefully reading the manuscript and for making use-
149.05, 149.24, 149.36, 149.51, 158.79, 159.57, 164.01, 164.20; ful suggestion to improve it: Dr. Atsushi Okada and Mr. Akira
HR-MS: Calcd for C20H22N4O [M+H]+ 335.1866. Found Higuchi for analytical and spectrum studies.
335.1858.
Calculation of CNS MPO The CNS MPO score was
Conflict of Interest All authors are employees of Taisho
calculated according to a previously reported method.19) The Pharmaceutical Co., Ltd.
cLogP value was calculated by a software from Daylight
Chemical Information Systems, Inc. The cLogD, pKa, and
tPSA were calculated usign the software from ACD/Labora-
tories.
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