Synthesis and biological evaluation of substituted imidazoquinoline derivatives as mPGES-1 inhibitors

Article abstract of DOI:10.1016/j.bmc.2013.01.018

We have previously reported 7-bromo-2-(2-chrolophenyl)-imidazoquinolin- 4(5H)-one (1) as a novel potent mPGES-1 inhibitor. To clarify the essential functional groups of 1 for inhibition of mPGES-1, we investigated this compound structure-activity relationship following substitution at the C(4)-position and N-alkylation at the N(1)-, the N(3)-, and the N(5)-positions of 1. To prepare the target compounds, we established a good methodology for selective N-alkylation of the imidazoquinolin-4-one, that is, selective alkylation of 1 at the N(3)- and N(5)-positions was achieved by use of an appropriate base and introduction of a protecting group at the nitrogen atom in the imidazole part, respectively. Replacement of the C(4)-oxo group with nitrogen- or sulfur- linked substituents gave decreased inhibitory activity for mPGES-1, and introduction of alkyl groups on the nitrogen atom at the N(1)-, the N(3)-, and the N(5)-positions resulted in even larger loss of inhibitory activity. These results revealed that the C(4)-oxo group, and the hydrogen atoms at the N(5)-position and the imidazole part were the best substituents.

Full text of DOI:10.1016/j.bmc.2013.01.018

Bioorganic & Medicinal Chemistry 21 (2013) 2068–2078
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis and biological evaluation of substituted imidazoquinoline
derivatives as mPGES-1 inhibitors
Tomoya Shiro a, Keisuke Kakiguchi b, Hirotada Takahashi a, Hidetaka Nagata a, Masanori Tobe b,
⇑
a Drug Research Division, Dainippon Sumitomo Pharma Co., Ltd, 3-1-98 Kasugade-naka, Konohana-ku, Osaka 554-0022, Japan
b Drug Research Division, Dainippon Sumitomo Pharma Co., Ltd, 33-94 Enoki, Suita, Osaka 564-0053, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
We have previously reported 7-bromo-2-(2-chrolophenyl)-imidazoquinolin-4(5H)-one (1) as a novel
potent mPGES-1 inhibitor. To clarify the essential functional groups of 1 for inhibition of mPGES-1, we
investigated this compound structure–activity relationship following substitution at the C(4)-position
and N-alkylation at the N(1)-, the N(3)-, and the N(5)-positions of 1. To prepare the target compounds,
we established a good methodology for selective N-alkylation of the imidazoquinolin-4-one, that is,
selective alkylation of 1 at the N(3)- and N(5)-positions was achieved by use of an appropriate base
and introduction of a protecting group at the nitrogen atom in the imidazole part, respectively. Replace-
ment of the C(4)-oxo group with nitrogen- or sulfur- linked substituents gave decreased inhibitory activ-
ity for mPGES-1, and introduction of alkyl groups on the nitrogen atom at the N(1)-, the N(3)-, and the
N(5)-positions resulted in even larger loss of inhibitory activity. These results revealed that the C(4)-
oxo group, and the hydrogen atoms at the N(5)-position and the imidazole part were the best
substituents.
Received 13 December 2012
Revised 28 December 2012
Accepted 6 January 2013
Available online 16 January 2013
Keywords:
mPGES-1
PGE2
Imidazoquinoline
Selective alkylation
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
for this shortcomings is that no report of X-ray crystallography of
complexes with the inhibitor and mPGES-1 in the open active con-
Arachidonic acid is transformed by cyclooxygenase 1 and 2
(COX-1 and COX-2) to prostaglandin H2 (PGH2), which is subse-
quently metabolized through terminal synthases to biologically ac-
tive prostanoids, such as thromboxane A2 (TXA2), PGI2, PGD2, PGF2,
PGE2.1 Among these prostanoids, PGE2 is well known as an impor-
tant lipid mediator with broad range of biological activities in var-
ious cells and tissues.2 Isomerization of PGH2 to PGE2 is catalyzed
by PGE2 synthases (PGES), which are classified into three isoforms:
microsomal PGES-1 (mPGES-1), -2 (mPGES-2), and cytosolic PGES
(cPGES).3 mPGES-1, which is functionally coupled with COX-2
and up-regulated by proinflammatory stimuli, such as IL-1, TNF-,
and LPS, is responsible for the release of PGE2.4 It is reported that
the symptoms of various diseases, such as collagen induced arthri-
tis, pain hypersensitivity, and neuropathic pain, can be signifi-
cantly relieved by suppression of PGE2 production in mPGES-1
knockout mice.5 Therefore, it is expected that inhibition of
mPGES-1 can lead to improvement of mPGES-1-related disorders.6
mPGES-1 inhibitors have recently been receiving a great deal of
attention as potential drug candidates. Although a number of
selective mPGES-1 inhibitors have been reported,7 information
on the essential functional groups, including a scaffold, for potent
mPGES-1 inhibitory activity has not been satisfactory. One reason
formation has made it difficult to perform rational drug design to
identify interaction sites between the amino acid residues of
mPGES-1 and the substituents of the inhibitors.8 Therefore, it is
necessary shed light on the essential functional groups involved
in mPGES-1 inhibition. We have previously reported the imidazo-
quinolin-4(5H)-one derivative 1 as a novel structural mPGES-1
inhibitor (Fig. 1).9 Preliminary examination of the chemical struc-
ture of this compound revealed that hydrophilic groups may be
preferable as C(4)-substituents, and that more information is re-
quired to clarify the roles of the hydrogen atoms at the N(5)-posi-
tion and the imidazole part. In this study, we set to clarify these
preliminary information by conducting the following chemical
modifications of 1; (1) replacement of the C(4)-oxo group with
nitrogen or sulfur atom linked substituents. (2) Introduction of
an alkyl group at the N(5)-position. (3) Introduction of an alkyl
group at the nitrogen atom in the imidazole part.
2. Results and discussion
2.1. Chemistry
The general synthetic methods of N-alkyl-imidazoquinolin-4-
one derivatives are shown in Scheme 1. N(1)- or N(3)-alkyl deriva-
tives can be synthesized from a common precursor, that is,
⇑
Corresponding author.
E-mail address: masanori-tobe@ds-pharma.co.jp (M. Tobe).
0968-0896/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmc.2013.01.018

T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
2069
mono-methylated compounds, which were subsequently purified
by column chromatography. NOE correlation between the proton
in the methyl group and the C(9)-proton was observed in the minor
product, but not in the major product, indicating that the major
product was the N(3)-methylated compound 8 and the minor
product was the N(1)-methylated compound 9. The major product
8 was next hydrolyzed by refluxing in 5 M HCl and subjected to 1H
NMR and HPLC analyses. Analysis data perfectly agree with that of
the product prepared by direct methylation of 1, allowing identifi-
cation of the structure of 2. Hydrolysis of 9 gave the N(1)-methyl-
imidazoquinolin-4(5H)-one derivative 3. The isolated yields of the
major and minor products in methylation of 7 were 76% and 21%,
respectively. The reason why methylation of 7 proceeded at both
the N(1)- and the N(3)-positions might be steric hindrance by the
chloro atom around the N(3)-position. Meanwhile, the steric hin-
drance by the C(9)-hydrogen atom would interrupt the methyla-
tion to the N(1)-position in the case of 1. Methylation of 2
afforded the dimethylated derivative 6, whose NMR spectrum
was consistent with that of the dimethylated compound
synthesized by direct methylation of 1, and whose NOE revealed
a correlation between the proton in the methyl group and the
C(6)-proton. Therefore, direct methylation of 1 initially proceeded
at the N(3)-position and then the N(5)-position was methylated. As
the chemical yield of 2 was poor (22%), we next tried to optimize
the reaction conditions. First, we investigated the effect of a base
on the selectivity (Table 1). Although the yield of 2 was improved
by use of Cs2CO3, the dimethylated compound 6 was also gener-
ated (entry 2). The reaction with K2CO3, which is a milder base
than Cs2CO3, increased the yield of 2 and decreased that of 3 (entry
3). Finally, reaction with the very mild base NaHCO3 afforded only
2 in spite of 8% conversion (entry 4). These results indicated that
selectivity of the N(3)-methylation can be improved by use of mild
bases.
Next, we investigated the effects of organic bases on regioselec-
tivity. Reaction of 1 with 2-tert-butylimino-2-diethylamino-1,3-
dimethylperhydro-1,3,2-diazaphosphorine (BEMP) or 1,8-diazabi-
cyclo[5.4.0]undec-7-ene (DBU) gave results similar to those ob-
tained with NaH or Cs2CO3 (entries 5 and 6), both of which are
strong organic bases. These findings led us to use weak organic
bases, such as N,N-diisopropylethylamine (i-Pr2EtN), triethylamine
(Et3N), and pyridine. Although the reaction with i-Pr2EtN at room
temperature for 5 h gave only 2 without generating 6, it reached
saturation at 20% conversion, and extension of the reaction time
had no beneficial effect on the conversion (entry 7). The reaction
was accelerated by use of higher temperatures, that is, 40% conver-
sion at 40 °C for 5 h, 62% at 60 °C for 3 h, and 100% at 60 °C for 5 h
(entries 8–10). The reaction was further accelerated at 80 °C, that
is, 42% conversion for 1 h and 100% for 3 h (entries 11 and 12).
On the other hand, increase of the concentration of 1 from 0.1 M
(entries 7–12) to 1.0 M (entries 13–15) shortened the reaction
time, that is, 74% conversion at 40 °C for 3 h, 85% at 60 °C for 3 h,
and 100% at 80 °C for 1 h. The isolated yields of 2 at 80 °C were
95% and 96% in 0.1 M and 1.0 M, respectively (entries 12 and 15).
The reaction with Et3N instead of i-Pr2EtN at 80 °C gave only 2 in
18%, but did not proceed at 40 °C (entries 16 and 17). On the other
hand, the reaction with pyridine did not proceed even at 80 °C (en-
try 18). These results indicated that selection of a suitable organic
base for the imidazole ring allows selective mono-methylation at
the N(3)-position. In all, we found that use of i-Pr2EtN in DMF at
80 °C for 1 h provided the best conditions for selective N(3)-meth-
ylation of 1.
O
3
Cl
4
5
HN
N
N
H
1
Br
1 :
mPGES-1 IC50 = 9.1 (nM)
Figure 1. Structure of 1.
substituted 4-chrolo-3-nitro-quinoline derivative, in 6 or 7 reac-
tion steps, respectively.10 Synthesis of the N(5)-alkyl derivatives
can be achieved by N-alkylation of the substituted isatoic anhy-
dride followed by seven reaction steps.11 However, these conven-
tional methods are not suitable for medicinal chemistry work,
since our aim was to optimize the substituents at the N(1)-, the
N(3)-, and the N(5)-positions, and to synthesize the desired ana-
logues in a minimum number of reaction steps. It was therefore
necessary to establish alternative convenient methods for the syn-
thesis of N-alkyl-imidazoquinolin-4-one derivatives. As there has
been no report on N-alkylation of the imidazoquinolin-4(5H)-one
derivatives, we initially conducted a direct N-alkylation of 1
(Scheme 2). Compound 1 was reacted with 1.5 equiv of methyl io-
dide (MeI) and sodium hydride (NaH) in N,N-dimethylformamide
(DMF) at room temperature for 2 h. Although four types of com-
pounds could be considered as possible mono-methylated com-
pounds 2–5 (Fig. 2), the reaction afforded only two products. MS
analysis indicated that one was mono-methylated, while the other
was di-methylated. To specify the position of the methyl group in
the mono-methylated compound, we carried out NOESY experi-
ment. A clear NOE correlation between the N(5)-proton and the
C(6)-proton indicated that the methyl group was introduced into
either the N(1)- or N(3)-position.
Next, to determine the position of the methyl group in the imid-
azole part, we performed methylation of the 4-chrolo-imidazo-
quinoline derivative 7. Like in the case of 1, 7 was reacted with
MeI and NaH in DMF. This reaction provided two types of
O
NO2
Cl
NO2
N
N
N
N
N
R1-NH2
HN
R''
NH
R1
5 steps
R1
R'
R'
R'
N
(1)-alkyl derivatives
O
R3
R3
N
N
N
HN
N
R''
R''
R''
N
H
N
N
R3-X
3 steps
3 steps
R'
O
R'
R'
N (3)-alkyl derivatives
O
O
R5
R5
N
HN
O
N
O
N
R5-X
R''
N
H
O
O
Next, we investigated alkylation of 1 with various alkyl halides
using the established optimum conditions (Table 2). Conversion to
the target compound was clearly lower with ethyl iodide (EtI) than
with MeI, that is, 10% conversion for 1 h and 18% for 5 h (entries 1
and 2). When the equivalent of EtI and i-Pr2EtN was increased
7 steps
R'
R'
R'
N (5)-alkyl derivatives
Scheme 1. Conventional synthetic methods of N-alkyl derivatives.

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T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
O
O
O
NOE
NOE
Me
N
Me
N
Cl
3
5
5
Me
N
a
HN
N
HN
6
+
e
6
H
H
N
N
H
N
Cl
Cl
6
Br
Br
1
2
Br
c
NOE
Cl
O
Cl
Cl
Cl
Me
N
Cl
Cl
3
N
N
N
N
4
HN
N
d
N
N
b
N
H
+
N
1
N
H
Me
Me
Cl
Br
H
Br
H
Br
9
NOE
NO E
Br
7
8
9
3
Scheme 2. Reagents and conditions. (a) MeI, NaH, DMF, rt, 3 h, 2 (22%) and 6 (63%); MeI, NaH, DMF, rt, 2 h, 8 (76%) and 9 (21%); (c) 5 M HCL aq, EtOH, reflux, 4 h, 2 (90%); (d)
5 M HCL aq, EtOH, reflux, 4 h, 3 (89%); (e) MeI, NaH, DMF, rt, 0.5 h, 6 (90%).
O
presence of i-Pr2EtN gave the SEM protected derivative 15 in 74%
yield without producing the di-SEM protected derivative (entry 1).
On the other hand, reaction with di-tert-butyl dicarbonate (Boc2O)
in the presence of N,N-dimethyl-4-aminopyridine (DMAP) afforded
the Boc protected derivative 16 in 72% yield (entry 2). Reaction with
dihydropyrane (DHP) in the presence of pyridinium p-toluenesulfo-
nate (PPTS) as a catalyst or with tosyl chloride (TsCl) in the presence
of i-Pr2EtN did not give the target compound (entries 3 and 4). As ex-
pected, a good NOE correlation between 15 and 16 indicated that
SEM and Boc groups can be introduced at the N(3)-position.
As shown in Scheme 3, reaction of 15 and 16 with MeI in the
presence of K2CO3 promptly proceeded and gave the N(5)-methyl
derivatives 17 and 18 in good yields. NOESY experiments of 17
and 18 showed a good NOE correlation between the N(5)-methyl
group and the C(6)-proton. We therefore succeeded in achieving
selective N(5)-mono-methylation via selective introduction of pro-
tecting group (SEM and Boc groups) into the N(3)-position of 1. As
imidazoquinoline derivatives having an SEM or Boc group on the
imidazole ring have not previously been reported, we investigated
the stability of the protecting groups in 17 and 18 (Table 4). The
SEM group of 17 was easily removed with trifluoroacetic acid
(TFA) at room temperature (Tcomp. = <15 min, entry 1), and was sta-
ble in the presence of the strong base NaOH (Entry 2). The SEM
group showed resistance to tetrabutylammonium fluoride (TBAF)
in tetrahydrofurane (THF) at room temperature, with deprotection
proceeding up to 15% after 3 h (data not shown). On the other
hand, under reflux condition, this group was completely removed
after 5 h (Entry 3). The Boc group of 18 was also easily removed
with TFA at room temperature (Tcomp. = <15 min, entry 4), while
in the presence of HCl complete deprotection took up to 8 h (Entry
5). Interestingly, the Boc group of 18 was easily removed with 1 M
NaOH and MeOH, leading to complete deprotection after 0.5 h (en-
try 6). This finding indicated that the Boc group could be removed
under not only general acidic conditions, but also under basic con-
Me
O
Cl
3
N
N
N
HN
HN
N
1
Me
Cl
Br
Br
Br
2
3
O
OMe
Cl
Cl
4
5
Me
N
N
N
N
N
H
N
H
Br
4
5
Figure 2. Structure of mono-methylated compounds.
(3.0 equiv), the reaction promptly proceeded, reaching 79% conver-
sion after 1 h (entry 3). The reaction was completed in 2 h and affor-
ded 10 in 96% isolated yield without generating the di-ethylated
compound (entry 4). Reaction of 1 with 3.0 equiv of normal-propyl
iodide (n-PrI)/benzyl bromide (BnBr) and i-Pr2EtN gave 11 and 12
in 95% and 98% isolated yields, respectively (entries 5 and 6). On
the other hand, reaction with 2-(bromomethyl)-pyridine hydrobro-
mide with 6.0 equiv of i-Pr2EtN for 3 h gave 13 in 94% isolated yield
(entry 7). Reaction with 2-bromoethanol, having a low reactivity
compared to EtI, took 5 h to reach 95% conversion and gave 14 in
88% isolated yield (entry 8). NOESY experiments of 10–14 showed
a similar NOE-correlation to 2. These results indicated that various
alkyl halides can be used for selective N(3)-alkylation of 1 using
i-Pr2EtN. This methodology seems to be suitable for medicinal
chemistry work.
From the findings above, it became clear that acidity of the N(3)-
proton was higher than that of the N(5)-proton and that direct and
selective N(5)-alkylation of 1 would be extremely difficult. We
therefore needed to develop an alternative route to prepare the
N(5)-alkyl derivatives. Our first attempt was to introduce an appro-
priate protecting group at the imidazole nitrogen atom, since reac-
tivity at the N(3)-position was higher than that at the N(5)
(Table 3). 2-(Trimethylsilyl)ethoxymethyl (SEM), tert-butoxycar-
bonyl (Boc), tetrahydropyranyl (THP), and tosyl (Ts) groups are well
known as protecting groups that can be easily removed.12 Reaction
of 1 with 2-(trimethylsilyl)ethoxymethyl chloride (SEMCl) in the
ditions. All deprotection reactions afforded only
byproducts.
4 without
The finding that the Boc group of 18 could be easily removed
by use of 1 M NaOH and MeOH encouraged us to investigate one-
pot synthesis of N(5)-alkyl derivatives from 16 (Scheme 3). After
complete conversion of 16 was indicated by LC/MS, 1 M NaOH
and MeOH were added to the reaction mixture, and the whole
was vigorously stirred for 0.5 h to give the N(5)-methyl derivative
4 in 92% yield. NOESY experiment of 4 showed NOE correlation

T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
2071
Table 1
Optimization of the N-methylation of 1
O
R1
N
O
Cl
MeI (1.5 eq.)
R2
N
N
HN
N
N
H
Base (1.5 eq.)
DMF
(0.1 M of 1)
Cl
Br
Br
1
2
2
R = Me, R = H :
1
1
2
6
R = R = Me :
Entry
Base
Temp. (°C)
Time (h)
Conversionb (%)
Isolated yield (%)
2
6
1a
2
3
4
5
6
7
8
9
10
11
12
13c
14c
15c
16
17
18
NaH
Cs2CO3
K2CO3
NaHCO3
BEMP
DBU
i-Pr2EtN
i-Pr2EtN
i-Pr2EtN
i-Pr2EtN
i-Pr2EtN
i-Pr2EtN
i-Pr2EtN
i-Pr2EtN
i-Pr2EtN
Et3N
rt
rt
rt
rt
rt
rt
rt
40
60
60
80
80
40
60
80
40
80
80
3
3
3
5
3
3
5
5
3
5
1
3
3
3
1
5
5
5
100
100
100
8
100
100
20
40
62
100
42
100
74
22
51
56
63
35
27
21
49
59
26
95
0
85
100
0
20
0
96
18
0
0
Et3N
pyridine
a
b
c
Result of reaction (a) in Scheme 2.
Conversion yields were detected by LC/MS at 254 nM.
1.0 mmol/ml (M) concentration of 1 in DMF.
Table 2
Introduction of alkyl groups to 1
O
R
O
Cl
N
R-X
N
HN
HN
N
N
H
-Pr EtN
i
DMF2, 80 oC
Cl
Br
Br
1
10−14
(1.0 M of 1)
Entry
R–X (equiv)
i-Pr2EtN (equiv)
Time (h)
R
Conversiona/isolated yield (%)
1
2
3
4
5
6
EtI (1.5)
EtI (1.5)
EtI (3.0)
EtI (3.0)
n-PrI (3.0)
BnBr (3.0)
HBr
1.5
1.5
3.0
3.0
3.0
3.0
1
5
1
2
2
1
Et
Et
Et
Et
n-Pr
Bn
10 (10/—)
10 (18/—)
10 (79/—)
10 (100/96)
11 (100/95)
12 (100/98)
7
8
6.0
3.0
3
5
13 (100/94)
14 (95/88)
Br
N
N
Br
HO
HO
a
Conversion yields were detected by LC/MS at 254 nM.
between the N(5)-methyl group and the C(6)-proton. Moreover,
1H NMR spectrum of 4 was not consistent with that of the
C(4)-methyl ether derivative 5 synthesized from 7,9 which strictly
proved that methylation of 15 and 16 selectively proceeded at the
N(5)-position, not at the C(4)-oxygen atom. The N(5)-ethyl and
the N(5)-benzyl derivatives 19 and 20 were also synthesized in
good yields using the same method. Hence, we could establish
a more convenient synthetic method of the N(5)-alkyl-imidazo-
quinolin-4-one derivatives from 1 than the conventional method
that requires many reaction steps.11
The synthetic methods for the C(4)-substituted derivatives
21–26 are shown in Scheme 4. Replacement of the chlorine
atom of
7 with corresponding amines or sodium sulfide
reagents under microwave irradiation (m.w.) provided 21–26. The

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T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
Table 3
Introduction of protective groups to 1
NOE
O
O
Reagent
(3.0 eq.)
R
N
Cl
H
N
N
HN
H
N
N
H
Additive
Solvent
Cl
Br
Br
1
15 16
−
Entry
Reagent
Additive (equiv)
Solvent
Temp. (°C)
Time (h)
R
Yielda (%)
1
2
3
4
SEMC1
Boc2O
DHP
i-Pr2EtN (3.0)
DMAP (0.5)
PPTS (0.5)
DMF
THF
THF
DMF
80
50
Reflux
80
1
1
8
8
SEM
Boc
THP
Ts
15 (74)
16 (72)
No reaction
No reaction
TsCl
i-Pr2EtN (3.0)
a
isolated yield.
of inhibitory activity compared to 1. mPGES-1 inhibitory activity
was also decreased by introduction of sterically large substitu-
ents, that is, the ethyl group (19) and the benzyl group (20).
We guessed that the proton at the N(5)-position may have inter-
acted with mPGES-1, leading to decreased inhibitory activity fol-
lowing N(5)-alkylation.
With regard to the N(1)- or the N(3)-methyl derivatives, the
inhibitory activity was completely diminished in the N(1)-methyl
derivative 3, and over 1000-fold loss in activity was seen in the
N(3)-methyl derivative 2. The N(3)-N(5)-dimethyl derivative 6 also
O
NOE
O
R
N
R
N
Me
HN
N
a
H
N
N
Cl
Cl
Br
Br
17
18
: R = SEM
15
16
: R = SEM
: R = Boc
: R = Boc
O
O
Boc
N
Cl
N
R1
showed no inhibition for mPGES-1 even at 10 lM. Finally, the pro-
HN
N
b
ton in the imidazole part was found to be essential for tight bind-
ing with the active site of mPGES-1.13
N
N
H
Cl
Br
Br
: R1 = Me
3. Conclusion
16
4
19
20
: R1 = Et
: R1 = Bn
In this study, we succeeded in establishing a novel convenient
synthetic route for medicinal chemistry work. We found that direct
alkylation of the imidazoquinolin-4(5H)-one derivative 1 in the
presence of i-Pr2EtN proceeds selectively at the N(3)-position,
and that N(5)-alkyl derivatives can be prepared by first protecting
the imidazole nitrogen atom with a Boc group and then removing
the protecting group. This methodology can significantly reduce
reaction steps for synthesis of the N(3)- or N(5)-alkyl imidazoquin-
olin-4-one derivatives compared to conventional methods, thereby
allowing an efficient SAR study. These novel synthetic findings can
contribute to the development of an efficient synthetic route for
the N-alkyl imidazoquinoline derivatives. To identify the essential
functional groups of the imidazoquinolin-4(5H)-one derivative 1
for potent mPGES-1 inhibitory activity, we carried out optimiza-
tion work, particularly of the substituents at the N(1), N(3), N(5),
C(4)-positions. As for the C(4)-substituent, amino groups gave
>400-fold loss of inhibitory activity. A thione or methylthio gave
decreased inhibitory activity compared to 1, suggesting that non-
basic small substituent could be considered best. The N(5)-alkyl
derivatives also showed weaker activity, indicating that the C(4)-
oxo group and the N(5)-proton were essential substituents for
strong inhibitory activity. Introduction of alkyl groups at the
N(1)- or N(3)-position of 1 resulted in large loss of inhibitory activ-
ity. These results indicate that the oxo group at the C(4)-position
and the protons at the N(1), N(3), and N(5)-positions were essential
for potent the inhibitory activity. On the basis of these findings, we
reconfirmed that the imidazoquinolin-4(5H)-one derivative 1 is
promising lead compound for further optimization. At present, fur-
ther SAR studies focused on substitution of the C(7)-bromine group
of 1 are in progress to find orally active mPGES-1 inhibitors with
good pharmacokinetic properties.
Scheme 3. Reagents and conditions. (a) Mel, K2CO3, DMF, rt, 2 h, 17 (94%), 18 (92%),
respectively; (b) Mel, EtI, or BnBr, K2CO3, DMF, rt, 2 h and then 1 M NaOH, MeOH, rt,
0.5 h, 4, 19, and 20 (90–92%) in two steps, respectively.
quinoline-4(5H)-thione structure of 26 was identified by
characteristic NOE correlation between the N(5)-proton and the
C(6)-proton, and FT-IR spectrum.
2.2. Biological evaluation
We initially investigated the effects of the substituents at the
C(4)-position. The results are summarized in Table 5. The amino
derivative 21, the monomethylamino 22, and the dimethylamino
23 exhibited remarkably lower inhibitory activity for mPGES-1
than 1 (IC50 values of 1068, 631, and 387 nM, respectively), indicat-
ing that basic substituents were not preferable for mPGES-1 inhib-
itory activity. The IC50 value of the thione derivative 26 for
inhibition of mPGES-1 was 83 nM, ninefold weaker than that of
1. No improvement in activity was seen with the methylthio deriv-
ative 24 and the ethylthio 25 compared to 1. As previously re-
ported, the IC50 values of the C(4)-methoxy derivative 5 and the
C(4)-unsubstituted derivative 27 for mPGES-1 inhibition were 62
and 251 nM, respectively.9 These results suggested that sterically
small and non-basic substituent should be placed onto the C(4)-po-
sition for potent inhibitory activity.
Next, in order to investigate the effects of the proton source at
the N(5)-position and the imidazole part of 1, the N-alkyl-imi-
dazoquinolin-4-one derivatives were evaluated. As shown in
Table 6, the N(5)-methyl derivative 4 resulted in ninefold loss

T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
2073
Table 4
Stability study of 17 and 18
O
O
R
N
Cl
Conditions
Me
Me
N
N
N
N
N
H
Cl
Br
Br
17
18
: R = SEM
: R = Boc
4
Entry
R
Condition
Deprotection ratea
b
c
T1/2
Tcomp.
1
2
3
4
5
6
SEM
SEM
SEM
Boc
Boc
Boc
TFA (100 equiv), rt
<5 min
No reaction for 12 h
0.5 h
<5 min
0.5 h
<15 min
1 M NaOH (10 equiv), THF, rt
1 M TBAF (3 equiv), THF, reflux
TFA (100 equiv), rt
4 M HCl (10 equiv), THF, rt
1 M NaOH (10 equiv), THF/MeOH, rt
5 h
<15 min
8 h
15 min
30 min
a
Deprotection rate was monitored by LC/MS at 254 nm.
T1/2 = half-life time of 17 or 18.
Tcomp. = the time which the deprotection completed.
b
c
R2
Table 5
Cl
Cl
Cl
Effects of substituents on the c(4)-position
N
N
a
b
c
or or
N
N
R1
S
N
H
N
H
Cl
Cl
N
N
HN
N
Br
Br
2
7
21
: R = NH2
N
H
2
N
H
22
23
24
25
: R = NHMe
d
2
: R = NMe2
Br
26
Br
2
: R = SMe
S
NOE
Cl
2
: R = SEt
H
N
N
H
Compound
R1
mPGES-1
IC50 (nM)
N
H
21
22
23
26
24
25
27a
5a
NH2
NHMe
NMe2
—
SMe
SEt
H
OMe
—
1068
631
387
83
31
59
251
62
9.1
Br
26
Scheme 4. Reagents and conditions: (a) NH4C1, i-Pr2EtN, NMP, 150 °C under m.w.,
1 h, 21 (48%); (b) 2 M Me2NH or 2 M MeNH2 in THF, NMP, 140 °C under m.w., 0.5 h,
22 (78%) or 23 (99%); (c) NaSMe or NaSEt, NMP, 80 °C under m.w., 1 h, 24 (80%) or
25 (94%);(d) NaSH/nH2O, NMP, 100 °C under m.w., 0.5 h, 26 (42%).
1a
4. Experimental
4.1. General
a
See Ref. 9.
Nuclear magnetic resonance spectra (NMR) were recorded on a
JEOL JMN-LA300 spectrometer or on a Bruker AVANCE 400 spec-
trometer. Chemical shifts (d) are given in parts per million, and tet-
ramethylsilane was used as internal standard for spectra obtained
in DMSO-d6 and CDCl3. All J values are given in Hz. Splitting pattern
designed as follows; s, singlet; d, doublet; t, triplet; q, quartet; m,
multiplet; br s, broad singlet; dd, double of doublets; dt, doublet of
triplets. Melting points were determined on an electrothermal
apparatus without correction. IR spectra were recorded on a JEOL
JNM-LA300 spectrometer as ATR. Low-resolution mass spectra
were recorded on a Waters ACQUITYÒ LCMS system under electron
spray ionization (ESI) conditions. High-resolution mass spectra
(HRMS) were recorded on a Thermo Fisher Scientific LTQ orbitrap
Discovery MS equipment. Elemental analysis was performed on a
CE Instrument EA1110 and a Yokokawa analytical system IC7000.
Reagents and solvents were used as obtained from commercial
suppliers without further purification. Column chromatography
was carried out using a Yamazen W-prep system and performed
using prepacked silica-gel columns. Reaction progress was deter-
mined by TLC analysis on a silica-gel coated glass plate. Visualiza-
tion was done with UV light (254 nm) or iodine. HPLC was
performed using a Waters ACQUITY UPLCÒ equipment.
4.1.1. 7-Bromo-2-(2-chlorophenyl)-3-methyl-3H-imidazo[4,5-
c]quinolin-4(5H)-one (2) and 7-bromo-2-(2-chlorophenyl)-3,5-
dimethyl-3H-imidazo[4,5-c]quinolin-4(5H)-one (6)
To a solution of 1 (30.0 mg, 0.0801 mmol) in DMF (1.0 mL) was
added NaH (60% in oil, 4.8 mg, 0.200 mmol) and MeI (0.008 mL,
0.120 mmol) at 0 °C and then the mixture was stirred for 3 h at
room temperature. To the reaction mixture, water and AcOEt were
added and then the mixture was extracted with ethyl acetate
(AcOEt) twice, and the combined extracts were washed with water
and brine, dried over Na2SO4. After filtrated, the solvent was re-
moved in vacuo. The residue was purified by silica gel column

2074
T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
Table 6
with AcOEt twice, and the combined extracts were washed with
Effects of substituents on the N(1)-, N(3)-, and N(5)-position
water and brine, dried over Na2SO4. After filtrated, the solvent
was removed in vacuo. The residue was purified by silica gel col-
umn chromatography (hexane/AcOEt = 2:1) 2 times. The separated
fractions were triturated with hexane/IPE, respectively, to afford 8
(23.3 mg, 76%) and 9 (6.7 mg, 21%) as a white solid, respectively.
Compound 8: 1H NMR (CDCl3, 300 MHz) d 8.38 (1H, d, J = 8.8 Hz),
8.22 (1H, d, J = 2.0 Hz), 7.68 (1H, dd, J = 2.0, 8.8 Hz), 7.49–7.57 (3H,
m), 7.40–7.47 (1H, m), 3.99 (3H, s); 13C NMR (DMSO-d6, 75 MHz) d
154.0, 146.4, 144.2, 136.3, 134.4, 132.4, 132.2, 130.9, 130.5, 130.0,
128.7, 127.4, 125.5, 123.4, 122.1, 120.7, 33.9; mp 255–256 °C; IR
R3
N
O
O
Cl
R2
N
N
N
HN
N
Cl
Me
Br
3
Br
Compound
R2
R3
mPGES-1
IC50 (nM)
(ATR)
m 1558, 1498, 1460, 1443, 1381, 1356, 1286, 1176, 1107,
4
Me
Et
Bn
—
H
H
H
H
H
—
Me
Bn
Me
H
85
106
226
>10,000
9810
>10,000
>10,000
9.1
1043, 1014 cmÀ1; HRMS (ESI) m/z calcd for C17H11BrCl2N3 (M+H)+:
405.9508, found: 405.9521; Anal. Calcd for C17H10BrCl2N3; C,
50.16; H, 2.48; N, 10.32. Found: C, 50.03; H, 2.58; N, 10.19. Com-
pound 9: 1H NMR (CDCl3, 300 MHz) d 8.36 (1H, d, J = 2.0 Hz), 8.19
(1H, d, J = 9.0 Hz), 7.72 (1H, dd, J = 2.0, 8.8 Hz), 7.64–7.67 (1H, m),
7.53–7.57 (2H, m), 7.44–7.50 (1H, m), 4.08 (3H, s); 13C NMR
(DMSO-d6, 75 MHz) d 152.3, 145.3, 144.8, 135.5, 134.5, 134.2,
133.0, 132.5, 132.1, 130.0, 129.8, 128.4, 127.4, 121.8, 121.3, 116.7,
19
20
3
2
12
6
Me
H
1a
a
See Ref. 9.
34.7; mp 219–221 °C; IR (ATR)
m 1560, 1491, 1450, 1369, 1350,
1313, 1288, 1153, 1111, 1039 cmÀ1; HRMS (ESI) m/z calcd for
C17H11BrCl2N3 (M+H)+: 405.9508, found: 405.9520; Anal. Calcd for
chromatography (CHCl3/MeOH = 10/1). The obtained solids were
triturated with diisopropylether (IPE), respectively, to afford 2
(6.8 mg, 22%) and 6 (19.8 mg, 63%) as a white solid.
C
17H10BrCl2N3; C, 50.16; H, 2.48; N, 10.32. Found: C, 50.09; H,
2.51; N, 10.27.
Compound 2: 1H NMR (DMSO-d6, 400 MHz) d 11.87 (1H, s), 7.98
(1H, d, J = 8.4 Hz), 7.65–7.73 (3H, m), 7.61 (1H, d, J = 1.5 Hz), 7.54–
7.58 (1H, m), 7.42 (1H, dd, J = 1.5, 8.4 Hz), 3.86 (3H, s); 13C NMR
(DMSO-d6, 100 MHz) d 155.4, 151.4, 143.1, 137.4, 133.1, 132.6,
132.3, 129.7, 128.5, 127.6, 125.0, 123.4, 121.2, 120.6, 118.1, 115.1,
4.1.4. Preparation of compound 2 from 8
A solution of 8 (25.0 mg, 0.061 mmol) in EtOH/H2O (2.0:0.1 mL)
and 5 M HCl (0.260 mL, 1.30 mmol) was stirred at reflux for 3 h.
After cooling to room temperature, the solvent was removed in va-
cuo. The obtained solid was triturated with CHCl3/MeOH (50:1) to
afford 2 (21.0 mg, 90%) as a white solid. 1H NMR spectra of 2 were
consistent with that of 2 synthesized from 1.
32.6; mp 313–315 °C; IR (ATR)
m 1672, 1543, 1460, 1414, 1392,
1375, 1313, 1217, 1159, 1072, 1039 cmÀ1; HRMS (ESI) m/z calcd
for C17H12BrClN3O (M+H)+: 387.9847, found: 387.9859; Anal. Calcd
for C17H11BrClN3OÁ0.50H2O; C, 51.35; H, 3.04; N, 10.57. Found: C,
51.43; H, 2.92; N, 10.43. Compound 6: 1H NMR (CDCl3, 300 MHz) d
8.15 (1H, d, J = 8.4 Hz), 7.55 (1H, d, J = 1.7 Hz), 7.47–7.52 (2H, m),
4.1.5. 7-Bromo-2-(2-chlorophenyl)-1-methyl-1H-imidazo[4,5-
c]quinolin-4(5H)-one (3)
The title compound 3 was synthesized from 9 in 89% yield
according to the procedure to prepare 2 from 8. 1H NMR (DMSO-
d6, 400 MHz) d 11.78 (1H, s), 8.14 (1H, d, J = 8.6 Hz), 7.71-7.73
(1H, m), 7.69 (1H, d, J = 2.0 Hz), 7.64–7.68 (2H, m), 7.54–7.59
(1H, m), 7.43 (1H, dd, J = 2.0, 8.6 Hz), 3.91 (3H, s); 13C NMR
(DMSO-d6, 100 MHz) d 157.7, 150.3, 138.5, 134.7, 134.0, 133.5,
132.7, 131.5, 130.2, 129.3, 128.2, 125.0, 123.9, 121.5, 118.9,
7.42–7.45 (1H, m), 7.35–7.41 (2H, m), 3.92 (3H, s), 3.72 (3H, s); 13
C
NMR (CDCl3, 75 MHz) d 155.9, 152.1, 143.0, 138.5, 134.4, 132.3,
131.8, 129.9, 128.8, 127.2, 125.7, 124.1, 122.4, 121.3, 117.9, 116.3,
33.2, 29.2; mp 250–251 °C; IR (ATR)
m 1651, 1568, 1554, 1464,
1443, 1419, 1400, 1365, 1306, 1257, 1225, 1159, 1122, 1082, 1039,
1001 cmÀ1; HRMS (ESI) m/z calcd for C18H14BrClN3O (M+H)+:
402.0003, found: 402.0009; Anal. Calcd for C18H13BrClN3O; C,
53.69; H, 3.25; N, 10.44. Found: C, 53.51; H, 3.32; N, 10.29.
111.7, 34.8; mp 313–315 °C; IR (ATR)
m 1672, 1543, 1460, 1414,
1392, 1375, 1313, 1217, 1159, 1072, 1039 cmÀ1; HRMS (ESI) m/z
calcd for C17H12BrClN3O (M+H)+: 387.9847, found: 387.9858; Anal.
Calcd for C17H11BrClN3OÁ0.25H2O; C, 51.93; H, 2.95; N, 10.69.
Found: C, 51.89; H, 2.91; N, 10.62.
4.1.2. Preparation of compound 6 from 2
To a solution of 2 (30.0 mg, 0.0772 mmol) in DMF (0.5 mL) was
added NaH (60% in oil, 4.3 mg, 0.180 mmol) and MeI (0.007 mL,
0.116 mmol) at room temperature and then the mixture was stirred
for 0.5 h. To the reaction mixture, water and AcOEt were added and
then the mixture was extracted with AcOEt twice, and the combined
extracts were washed with water and brine, dried over Na2SO4. After
filtrated, the solvent was removed in vacuo. The residue was purified
by silica gel column chromatography (CHCl3/MeOH = 30/1) and trit-
urated with IPE to afford 6 (27.9 mg, 90%) as a white solid. 1H NMR
spectra of 6 were consistent with that of 6 synthesized from 1.
4.1.6. Preparation of compound 2 from 1 (in Table 1, entry 15)
To a solution of 1 (30.0 mg, 0.0801 mmol) in DMF (0.08 mL) was
added i-Pr2EtN (0.021 mL, 0.120 mmol) and MeI (0.008 mL,
0.120 mmol) at room temperature and then the mixture was stir-
red for 1 h at 80 °C. After cooling to room temperature, water
and AcOEt were added and then the mixture was extracted with
AcOEt twice, and the combined extracts were washed with water
and brine, dried over Na2SO4. After filtrated, the solvent was re-
moved in vacuo. The residue was purified by silica gel column
chromatography (CHCl3/MeOH = 10:1) and triturated with IPE to
afford 2 (30.7 mg, 96%) as a white solid. 1H NMR spectra of 2 were
consistent with that of 2 synthesized from 1 using NaH.
4.1.3. 7-Bromo-4-chloro-2-(2-chlorophenyl)-3-methyl-3H-
imidazo[4,5-c]quinoline (8) and 7-bromo-4-chloro-2-(2-
chlorophenyl)-1-methyl-1H-imidazo[4,5-c]quinoline (9)
To a solution of 7 (30.0 mg, 0.0763 mmol) in DMF (1.0 mL) was
added NaH (60% in oil, 4.6 mg, 0.191 mmol) and MeI (0.007 mL,
0.114 mmol) at 0 °C and then the mixture was stirred for 2 h at
room temperature. The reaction mixture was cooled with ice bath,
water and AcOEt were added and then the mixture was extracted
4.1.7. 7-Bromo-2-(2-chlorophenyl)-3-ethyl-3H-imidazo[4,5-
c]quinolin-4(5H)-one (10)
To a solution of 1 (30.0 mg, 0.0801 mmol) in DMF (0.08 mL) was
added i-Pr2EtN (0.041 mL, 0.240 mmol) and EtI (0.019 mL,

T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
2075
0.240 mmol) at room temperature and then the mixture was stir-
red for 5 h at 80 °C. After cooling to room temperature, water
and AcOEt were added and then the mixture was extracted with
AcOEt twice, and the combined extracts were washed with water
and brine, dried over Na2SO4. After filtrated, the solvent was re-
moved in vacuo. The residue was purified by silica gel column
chromatography (CHCl3/MeOH = 10:1) and triturated with IPE to
afford 10 (31.0 mg, 96%) as a white solid. 1H NMR (DMSO-d6,
400 MHz) d 11.89 (1H, s), 7.98 (1H, d, J = 8.4 Hz), 7.64–7.74 (3H,
m), 7.64 (1H, d, J = 1.9 Hz), 7.55–7.59 (1H, m), 7.42 (1H, dd,
J = 1.9, 8.4 Hz), 4.24 (2H, q, J = 7.1 Hz), 1.23 (3H, t, J = 7.1 Hz); 13C
NMR (DMSO-d6, 100 MHz) d 155.0, 150.6, 143.5, 137.5, 133.2,
132.4, 132.3, 129.7, 128.8, 127.6, 125.0, 123.4, 120.7, 120.4,
calcd for C22H15BrClN4O (M+H)+: 465.0112, found: 465.0112; Anal.
Calcd for C22H14BrClN4OÁ0.25H2O; C, 56.19; H, 3.11; N, 11.91. Found:
C, 55.96; H, 3.05; N, 11.89.
4.1.11. 7-Bromo-2-(2-chlorophenyl)-3-(2-hydroxyethyl)-3H-
imidazo[4,5-c]quinolin-4(5H)-one (14)
The title compound 14 was synthesized from 1 in 88% yield
using 2-bromoethanol according to the procedure to prepare 10.
1H NMR (DMSO-d6, 300 MHz) d 11.88 (1H, s), 7.99 (1H, d,
J = 8.4 Hz), 7.52-7.70 (5H, m), 7.42 (1H, dd, J = 1.8, 8.4 Hz), 4.80
(1H, t, J = 5.6 Hz), 4.25 (2H, br s), 3.62 (1H, q, J = 5.6 Hz); 13C NMR
(DMSO-d6, 75 MHz) d 155.2, 151.8, 143.6, 137.5, 133.2, 133.1,
132.0, 129.5, 129.0, 127.4, 125.1, 123.4, 120.7, 118.1, 115.1, 60.3,
118.1, 115.0, 40.8, 16.3; mp 312–314 °C; IR (ATR)
m
2816, 1660,
48.1; mp 271–275 °C; IR (ATR) m 2852, 1660, 1591, 1545, 1450,
1587, 1541, 1427, 1392, 1379, 1333, 1321, 1205, 1153, 1068,
1041 cmÀ1; HRMS (ESI) m/z calcd for C18H14BrClN3O (M+H)+:
402.0003, found: 402.0005; Anal. Calcd for C18H13BrClN3OÁ
0.25H2O; C, 53.10; H, 3.34; N, 10.32. Found: C, 53.10; H, 3.25; N,
10.23.
1425, 1390, 1373, 1346, 1333, 1317, 1188, 1111, 1080, 1070,
1043 cmÀ1; HRMS (ESI) m/z calcd for C18H14BrClN3O2 (M+H)+:
417.9952, found: 417.9954; Anal. Calcd for C18H13BrClN3O2Á
1.00H2O; C, 49.51; H, 3.46; N, 9.62. Found: C, 49.47; H, 3.34; N,
9.54.
4.1.8. 7-Bromo-2-(2-chlorophenyl)-3-(1-propyl)-3H-
4.1.12. 7-Bromo-2-(2-chlorophenyl)-3-((2-
imidazo[4,5-c]quinolin-4(5H)-one (11)
(trimethylsilyl)ethoxy)methyl)-3H-imidazo[4,5-c]quinolin-
4(5H)-one (15)
The title compound 11 was synthesized from 1 in 95% yield
using n-PrI according to the procedure to prepare 10. 1H NMR
(DMSO-d6, 400 MHz) d 11.94 (1H, s), 7.99 (1H, d, J = 8.4 Hz),
7.66–7.73 (3H, m), 7.64 (1H, d, J = 1.8 Hz), 7.55–7.59 (1H, m),
7.43 (1H, dd, J = 1.8, 8.4 Hz), 4.22 (2H, t, J = 7.0 Hz), 1.61–1.67
(2H, m), 0.66 (3H, t, J = 7.4 Hz); 13C NMR (DMSO-d6, 100 MHz) d
155.1, 151.5, 143.9, 138.0, 133.7, 133.1, 132.8, 130.3, 129.4,
128.1, 125.5, 124.4, 124.0, 121.3, 118.6, 115.5, 47.4, 24.3, 11.0;
To a solution of 1 (300.0 mg, 0.801 mmol) in DMF (5.0 mL) was
added i-Pr2EtN (0.419 mL, 2.40 mmol) and SEMCl (0.24 mL,
0.240 mmol) at room temperature and then the mixture was stir-
red for 1 h at 80 °C. After cooling to room temperature, water
and AcOEt were added and then the mixture was extracted with
AcOEt twice, and the combined extracts were washed with water
and brine, dried over Na2SO4. After filtrated, the solvent was re-
moved in vacuo. The residue was purified by silica gel column
chromatography (CHCl3/MeOH = 30/1) and triturated with IPE to
afford 15 (299.0 mg, 74%) as a white solid. 1H NMR (DMSO-d6,
300 MHz) d 12.17 (0.9H, br s), 8.17 (1H, d, J = 8.4 Hz), 7.77–7.87
(4H, m), 7.68–7.73 (1H, m), 7.60 (1H, dd, J = 2.0, 8.4 Hz), 5.86
(2H, s), 3.54 (2H, t, J = 8.3 Hz), 0.85 (2H, t, J = 8.3 Hz), À0.01 (9H,
s); 13C NMR (DMSO-d6, 75 MHz) d 155.1, 151.7, 143.3, 137.5,
133.3, 132.5, 132.2, 129.8, 128.6, 127.4, 125.2, 123.6, 121.0,
120.8, 118.2, 114.8, 73.3, 65.5, 17.1, À1.5; mp 218–219 °C; IR
mp 288–290 °C; IR (ATR)
1458, 1389, 1336, 1138, 1047 cmÀ1; HRMS (ESI) m/z calcd for
19H16BrClN3O (M+H)+: 416.0160, found: 416.0162; Anal. Calcd
m 2877, 1662, 1597, 1578, 1543, 1543,
C
for C19H15BrClN3O; C, 54.76; H, 3.63; N, 10.08. Found: C, 54.70;
H, 3.63; N, 10.09.
4.1.9. 3-Benzyl-7-bromo-2-(2-chlorophenyl)-3H-imidazo[4,5-
c]quinolin-4(5H)-one (12)
The title compound 12 was synthesized from 1 in 98% yield
using BnBr according to the procedure to prepare 10. 1H NMR
(DMSO-d6, 400 MHz) d 11.94 (1H, s), 8.01 (1H, d, J = 8.4 Hz),
7.65–7.66 (2H, m), 7.59–7.63 (1H, m), 7.44–7.50 (3H, m), 7.18–
7.19 (3H, m), 6.83–6.86 (2H, m), 5.62 (2H, s); 13C NMR (DMSO-
d6, 100 MHz) d 155.2, 151.3, 143.4, 137.4, 136.6, 133.2, 132.3,
132.2, 129.7, 128.5, 128.4, 127.5, 127.4, 126.7, 125.1, 123.4,
(ATR)
m 2862, 1659, 1589, 1543, 1458, 1387, 1377, 1333, 1319,
1246, 1215, 1151, 1095, 1078, 1038 cmÀ1; HRMS (ESI+) m/z calcd
for C22H24BrClN3O2Si (M+H)+: 504.0504, found: 504.0504; Anal.
Calcd for C22H23BrClN3O2 Si; C, 52.34; H, 4.59; N, 8.32. Found: C,
52.50; H, 4.63; N, 8.37.
120.8, 120.6, 118.2, 115.0, 48.2; mp 314–316 °C; IR (ATR)
m
2845,
4.1.13. tert-Butyl 7-bromo-2-(2-chlorophenyl)-4-oxo-4,5-
dihydro-3H-imidazo[4,5-c]quinoline-3-carboxylate (16)
1662, 1589, 1540, 1456, 1421, 1390, 1373, 1334, 1319, 1192,
1155, 1105, 1072, 1049, 1034 cmÀ1; HRMS (ESI) m/z calcd for
A mixture of 1 (250.0 mg, 0.667 mmol) and DMAP (40.7 mg,
0.334 mmol) in THF (10.0 mL) was stirred at 50 °C for 5 min and
then Boc2O (284.2 mg, 2.00 mmol) was added and the reaction
mixture was sttired at 50 °C for 1 h. After cooling to room temper-
ature, the solvent of the mixture was removed in vacuo. The resi-
due was purified by silica gel column chromatography (hexane/
AcOEt = 1:1) and triturated with IPE to afford 16 (241.0 mg, 72%)
as a white amorphous solid. 1H NMR (DMSO-d6, 300 MHz) d
11.72 (1H, s), 8.16 (1H, d, J = 8.4 Hz), 7.67 (1H, d, J = 1.7 Hz), 7.57
(1H, dd, J = 1.4, 6.9 Hz), 7.49–7.53 (2H, m), 7.40–7.47 (2H, m),
1.51 (9H, s); 13C NMR (DMSO-d6, 75 MHz) d 155.4, 151.8, 146.2,
145.8, 137.5, 133.9, 131.6, 131.5, 130.1, 129.5, 126.9, 126.3,
124.4, 123.1, 120.4, 118.6, 114.7, 87.1, 27.3; mp 165–180 °C; IR
C
23H16BrClN3O (M+H)+: 464.0160, found: 464.0160; Anal. Calcd
for C23H15BrClN3OÁ0.25H2O; C, 58.87; H, 3.33; N, 8.95. Found: C,
59.08; H, 3.30; N, 8.91.
4.1.10. 7-Bromo-2-(2-chlorophenyl)-3-(pyridin-2-ylmethyl)-3H-
imidazo[4,5-c]quinolin-4(5H)-one (13)
The title compound 13 was synthesized from 1 in 94% yield using
3.0 equiv of 2-(bromomethyl)pyridine hydrobromide and 6.0 equiv
of i-Pr2EtN according to the procedure to prepare 10. 1H NMR
(DMSO-d6, 300 MHz) d 11.85 (1H, s), 8.32 (1H, d, J = 4.0 Hz), 8.02
(1H, d, J = 8.4 Hz), 7.59–7.67 (3H, m), 7.54 (1H, dt, J = 3.8, 10.8 Hz),
7.36–7.47 (3H, m), 7.17–7.21 (1H, m), 7.01 (1H, d, J = 7.9 Hz), 5.68
(2H, s); 13C NMR (DMSO-d6, 75 MHz) d 155.4, 155.2, 151.8, 149.0,
143.3, 137.5, 136.8, 133.1, 132.4, 132.1, 129.6, 128.5, 127.3, 125.2,
123.5, 122.6, 121.2, 121.0, 120.8, 118.2, 115.1, 49.6; mp 283–
(ATR)
m 2862, 2359, 1761, 1655, 1591, 1547, 1454, 1387, 1365,
1336, 1317, 1261, 1188, 1147, 1095, 1066, 1045 cm-1; HRMS
(ESI+) m/z calcd for C21H18BrClN3O3 (M+H)+: 474.0215, found:
474.0215; Anal. Calcd for C21H17BrClN3O3; C, 53.13; H, 3.61; N,
8.85. Found: C, 53.35; H, 3.79; N, 8.62.
285 °C; IR (ATR)
m 2848, 1664, 1591, 1545, 1441, 1416, 1392, 1371,
1335, 1323, 1192, 1157, 1109, 1072, 1051 cmÀ1; HRMS (ESI) m/z

2076
T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
4.1.14. 7-Bromo-2-(2-chlorophenyl)-5-methyl-3-((2-
C
17H12BrClN3O (M+H)+: 387.9847, found: 387.9842; Anal. Calcd
(trimethylsilyl)ethoxy)methyl)-3H-imidazo[4,5-c]quinolin-
4(5H)-one (17)
for C17H11BrClN3OÁ1.00H2O; C, 50.21; H, 3.22; N, 10.33. Found: C,
50.00; H, 2.82; N, 10.12.
To a solution of 15 (100.0 mg, 0.198 mmol) in DMF (1.0 mL) was
added K2CO3 (53.5 mg, 0.396 mmol) and MeI (0.026 mL,
0.396 mmol) at room temperature and then the mixture was stir-
red for 2 h. To the reaction mixture, water and AcOEt were added
and then the mixture was extracted with AcOEt twice, and the
combined extracts were washed with water and brine, dried over
Na2SO4. After filtrated, the solvent was removed in vacuo. The res-
idue was purified by silica gel column chromatography (CHCl3/
MeOH = 30:1) and triturated with IPE to afford 17 (96.6 mg, 94%)
as a white solid. 1H NMR (DMSO-d6, 300 MHz) d 8.27 (1H, d,
J = 8.3 Hz), 8.03 (1H, d, J = 1.7 Hz), 7.83–7.88 (2H, m), 7.80 (1H,
dd, J = 2.2, 7.6 Hz), 7.68–7.81 (2H, m), 5.88 (2H, s), 3.90 (3H, s),
3.53 (2H, t, J = 8.3 Hz), 0.85 (2H, t, J = 8.3 Hz), 0.00 (9H, s); 13C
NMR (DMSO-d6, 75 MHz) d 154.5, 151.8, 142.3, 138.4, 133.3,
132.5, 132.2, 129.8, 128.5, 127.4, 125.5, 123.8, 122.0, 120.2,
118.4, 115.5, 73.3, 65.5, 29.1, 17.1, À1.53; mp 205–218 °C; IR
4.1.17. 7-Bromo-2-(2-chlorophenyl)-5-ethyl-imidazo[4,5-
c]quinolin-4(5H)-one (19)
The title compound 19 was synthesized from 16 in 92% yield
using EtI according to the procedure to prepare 4 from 16. 1H
NMR (DMSO-d6, 300 MHz) d 13.92 (0.5H, br s), 8.13 (1H, d,
J = 8.3 Hz), 7.87 (1H, s), 7.78 (1H, dd, J = 1.9, 7.2 Hz), 7.66 (1H, d,
J = 7.5 Hz), 7.49–7.59 (3H, m), 4.41 (2H, q, J = 7.0 Hz), 1.24 (3H, t,
J = 7.0 Hz); 13C NMR (DMSO-d6, 75 MHz) d 154.1, 150.0, 137.3,
132.2, 131.5, 130.2, 129.5, 127.4, 125.0, 124.1, 121.7, 117.9, 36.5,
13.0; mp 274–276 °C; IR (ATR)
m 2848, 1664, 1599, 1587, 1541,
1427, 1392, 1381, 1371, 1333, 1321, 1205, 1153, 1068,
1041 cmÀ1; HRMS (ESI) m/z calcd for C18H14BrClN3O (M+H)+:
402.0003, found: 402.0003; Anal. Calcd for C18H13BrClN3OÁ
0.25H2O; C, 53.10; H, 3.34; N, 10.32. Found: C, 53.16; H, 3.26; N,
10.29.
(ATR)
m 2947, 2893, 1655, 1568, 1554, 1470, 1456, 1439, 1398,
1346, 1309, 1246, 1221, 1151, 1119, 1093, 1080, 1055,
1003 cmÀ1; HRMS (ESI+) m/z calcd for C23H26BrClN3O2Si (M+H)+:
518.0661, found: 518.0660. HPLC: 98.74%.
4.1.18. 5-Benzyl-7-bromo-2-(2-chlorophenyl)-imidazo[4,5-
c]quinolin-4(5H)-one (20)
The title compound 20 was synthesized from 16 in 90% yield
using BnBr according to the procedure to prepare 4 from 16. 1H
NMR (DMSO-d6, 300 MHz) d 14.03 (0.7H, br s), 8.13 (1H, d,
J = 8.3 Hz), 7.82 (1H, dd, J = 2.0, 7.2 Hz), 7.68 (1H, dd, J = 1.5,
7.7 Hz), 7.64 (1H, d, J = 1.5 Hz), 7.49–7.60 (3H, m), 7.30–7.35 (2H,
m), 7.20–7.26 (3H, m), 5.67 (2H, s); 13C NMR (DMSO-d6, 75 MHz)
d 149.7, 148.1, 137.6, 136.9, 132.2, 131.6, 130.2, 129.5, 128.8,
128.0, 127.4, 127.1, 126.4, 125.3, 124.1, 121.3, 118.8, 115.6, 44.5;
4.1.15. tert-Butyl 7-bromo-2-(2-chlorophenyl)-5-methyl-4-oxo-
4,5-dihydro-3H-imidazo[4,5-c]quinoline-3-carboxylate (18)
To a solution of 16 (65.0 mg, 0.137 mmol) in DMF (1.0 mL) was
added K2CO3 (37.0 mg, 0.274 mmol) and MeI (0.018 mL,
0.274 mmol) at room temperature and then the mixture was stir-
red for 2 h. To the reaction mixture, water and AcOEt were added
and then the mixture was extracted with AcOEt twice, and the
combined extracts were washed with water and brine, dried over
Na2SO4. After filtrated, the solvent was removed in vacuo. The res-
idue was purified by silica gel column chromatography (hexane/
AcOEt = 1:1) and triturated with IPE to afford 18 (61.6 mg, 92%)
as a white solid. 1H NMR (DMSO-d6, 300 MHz) d 8.11 (1H, d,
J = 8.3 Hz), 7.89 (1H, d, J = 1.7 Hz), 7.61–7.70 (3H, m), 7.51–7.58
(2H, m), 3.73 (3H, s), 1.34 (9H, s); 13C NMR (DMSO-d6, 75 MHz) d
152.9, 150.5, 145.6, 142.8, 139.1, 132.8, 132.3, 131.9, 129.3,
129.2, 127.3, 125.5, 124.3, 122.8, 120.0, 118.4, 114.6, 86.6, 29.6,
mp 294–295 °C; IR (ATR)
m 2846, 1668, 1591, 1543, 1454, 1421,
1390, 1373, 1360, 1335, 1321, 1190, 1151, 1103, 1072,
1049 cmÀ1; HRMS (ESI) m/z calcd for C23H16BrClN3O (M+H)+:
464.0160, found: 464.0160; Anal. Calcd for C23H15BrClN3O; C,
59.44; H, 3.25; N, 9.04. Found: C, 59.18; H, 3.31; N, 9.03.
4.1.19. 7-Bromo-2-(2-chlorophenyl)-imidazo[4,5-c]quinolin-4-
amine (21)
A mixture of 7 (80.0 mg, 0.203 mmol) and NH4Cl (109 mg,
2.03 mmol) and i-Pr2EtN (0.328 mL, 2.03 mmol) in N-methylpyrr-
olidone (NMP) (1.5 mL) was stirred at 150 °C for 1 h under micro-
wave irradiation. After cooling to room temperature, water and
AcOEt were added. The mixture was extracted with AcOEt twice,
and the combined extracts were washed with water and brine,
dried over Na2SO4. After filtrated, the solvent was removed in va-
cuo. The residue was purified by silica gel column chromatography
(CHCl3/MeOH = 10:1) and triturated with CHCl3 to afford 21
26.6; mp 323–325 °C; IR (ATR)
m 1761, 1670, 1570, 1450, 1432,
1396, 1371, 1358, 1309, 1284, 1261, 1238, 1196, 1147, 1117,
1080, 1055, 1001 cmÀ1; HRMS (ESI+) m/z calcd for C22H20BrClN3O3
(M+H)+: 488.0371, found: 488.0372. HPLC: 98.83%.
4.1.16. 7-Bromo-2-(2-chlorophenyl)-5-methyl-imidazo[4,5-
c]quinolin-4(5H)-one (4)
To a solution of 16 (30.0 mg, 0.0632 mmol) and K2CO3 (13.0 mg,
0.0948 mmol) in DMF (1.0 mL) was added MeI (0.006 mL,
0.0948 mmol) at room temperature and then the mixture was stir-
red for 2 h. After the methylation was completed, MeOH (3.0 mL)
and 1 M NaOHaq. (0.6 mL) were added and then the mixture was
vigorously stirred for 30 min. To the reaction mixture, AcOEt and
water were added and then the mixture was extracted with AcOEt
twise, and the combined extracts were washed with water and
brine, dried over Na2SO4. After filtrated, the solvent was removed
in vacuo. The residue was purified by silica gel column chromatog-
raphy (CHCl3/MeOH = 10:1) and triturated with IPE to afford 4
(22.7 mg, 92% in two steps) as a white solid. 1H NMR (DMSO-d6,
400 MHz) d 8.11 (1H, d, J = 8.4 Hz), 7.84 (1H, d, J = 1.7 Hz), 7.79
(1H, dd, J = 1.8, 7.5 Hz), 7.66 (1H, dd, J = 1.4, 7.8 Hz), 7.50–7.60
(3H, m), 3.74 (3H, s); 13C NMR (DMSO-d6, 100 MHz) d 158.4,
155.2, 149.4, 138.5, 132.6, 132.2, 131.6, 130.2, 129.3, 127.4,
125.1, 123.8, 121.6, 118.4, 116.5, 113.8, 29.2; mp 316–318 °C; IR
(36.0 mg, 48%) as a
pale brown solid. 1H NMR (DMSO-d6,
300 MHz) d 13.63 (0.4H, br s), 8.05 (1H, d, J = 8.4 Hz), 7.85 (1H,
br s), 7.68–7.72 (2H, m), 7.51–7.61 (2H, m), 7.38 (1H, dd, J = 1.9,
8.5 Hz), 6.93 (2H, br s); 13C NMR (DMSO-d6, 75 MHz) d 152.5,
147.5, 145.8, 132.4, 131.9, 131.5 130.2, 129.9, 127.5, 127.4, 123.7,
123.1, 119.9; mp 283–285 °C; IR (ATR)
1651, 1579, 1522, 1471, 1448, 1390, 1273, 1105, 1086, 1063,
1043 cmÀ1 MS (ESI) m/z calcd for C16H11BrClN4 (M+H)+:
m 3477, 3437, 3302, 3142,
;
372.9850, found: 372.9850; Anal. Calcd for C16H10BrClN4Á0.75H2O;
C, 49.64; H, 2.99; N, 14.47. Found: C, 49.57; H, 2.72; N, 14.24.
4.1.20. 7-Bromo-2-(2-chlorophenyl)-N-methyl-imidazo[4,5-
c]quinolin-4-amine (22)
A mixture of 7 (100.0 mg, 0.254 mmol) and 2 M methylamine in
THF (0.640 mL, 1.27 mmol) in NMP (3.0 mL) was stirred at 140 °C
for 0.5 h under microwave irradiation. After cooling to room tem-
perature, water and AcOEt were added. The mixture was extracted
with AcOEt twice, and the combined extracts were washed with
water and brine, dried over Na2SO4. After filtrated, the solvent
(ATR)
m
3080, 1676, 1647, 1605, 1558, 1473, 1458, 1421, 1400,
1329, 1198, 1147, 1057 cmÀ1
;
HRMS (ESI) m/z calcd for

T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
2077
was removed in vacuo. The residue was purified by silica gel col-
umn chromatography (hexane/AcOEt = 1:1) and triturated with
hexane/IPE to afford 22 (82.0 mg, 78%) as a white solid. 1H NMR
(DMSO-d6, 300 MHz) d 13.66 (0.6H, s), 7.81 (1H, br s), 7.78 (1H,
s), 7.67–7.70 (1H, m), 7.51–7.60 (2H, m), 7.37 (2H, d, J = 8.4 Hz),
3.04 (3H, d, J = 4.0 Hz); 13C NMR (DMSO-d6, 75 MHz) d 151.8,
147.2, 145.9, 133.3, 132.2, 132.0, 131.4, 130.2, 129.9, 128.0,
127.4, 123.5, 123.0, 119.9, 113.4, 27.3; mp 233–234 °C; IR (ATR)
for C18H13BrClN3S; C, 51.63; H, 3.13; N, 10.04. Found: C, 51.85; H,
3.41; N, 9.89.
4.1.24. 7-Bromo-2-(2-chlorophenyl)-imidazo[4,5-c]quinoline-
4(5H)-thione (26)
A mixture of 7 (100 mg, 0.254 mmol) and sodium hydrosulfide
hydrate (NaSH/nH2O, 71.0 mg) in NMP (1.0 mL) was stirred at
100 °C for 0.5 h under microwave irradiation. After cooling to room
temperature, water and AcOEt were added. The mixture was ex-
tracted with AcOEt twice, and the combined extracts were washed
with water and brine, dried over Na2SO4. After filtrated, the solvent
was removed in vacuo. The residue was triturated with CHCl3 and
water to afford 26 (42.0 mg, 42%) as a pale brown solid. 1H NMR
(DMSO-d6, 300 MHz) d 13.92 (0.7H, br s), 13.44 (0.6H, br s), 8.11
(1H, d, J = 8.6 Hz), 7.96 (1H, d, J = 1.7 Hz), 7.79 (1H, d, J = 7.3 Hz),
7.66 (1H, d, J = 7.7 Hz), 7.48–7.60 (3H, m); 13C NMR (DMSO-d6,
75 MHz) d 137.8, 132.4, 131.8, 130.0, 129.3, 127.3, 127.0, 123.9,
m
3435, 3373, 2964, 1630, 1591, 1581, 1524, 1514, 1450, 1435,
1414, 1392, 1377, 1267, 1246, 1217, 1130, 1117, 1065,
1043 cmÀ1; HRMS (ESI+) m/z calcd for C17H13BrClN4 (M+H)+:
387.0007, found: 387.0008; Anal. Calcd for Anal. Calcd for
C17H12BrClN4; C, 52.67; H, 3.12; N, 14.45. Found: C, 52.95; H,
3.17; N, 14.40.
4.1.21. 7-Bromo-2-(2-chlorophenyl)-N,N-dimethyl-imidazo[4,5-
c]quinolin-4-amine (23)
The title compound 23 was synthesized from 7 in 99% yield
using 2 M dimethylamine in THF according to the procedure to
prepare 22. 1H NMR (DMSO-d6, 300 MHz) d 13.73 (0.8H, s), 8.07
(1H, d, J = 8.4 Hz), 7.84–7.88 (1H, m), 7.76 (1H, d, J = 1.8 Hz),
7.66–7.70 (1H, m), 7.52–7.59 (2H, m), 7.37 (1H, dd, J = 2.0,
8.4 Hz), 3.55 (6H, s); 13C NMR (DMSO-d6, 75 MHz) d 151.6, 146.0,
145.1, 135.5, 132.1, 131.9, 131.3, 130.4, 129.5, 128.2, 127.8,
127.4, 123.6, 122.9, 120.2, 112.9, 38.8; mp 194–195 °C; IR (ATR)
121.3, 119.1; mp 315–316 °C; IR (ATR)
1587, 1574, 1446, 1427, 1387, 1338, 1277, 1225, 1207, 1194,
1101, 1082, 1070, 1043 cmÀ1
HRMS (ESI+) m/z calcd for
16H10BrClN3S (M+H)+: 389.9462, found: 389.9454; Anal. Calcd
m 3402, 2978, 2362, 1626,
;
C
for C16H9BrClN3SÁ0.25H2O; C, 48.63; H, 2.42; N, 10.63. Found: C,
48.93; H, 2.57; N, 10.33.
4.2. Biological assays
m
3435, 2926, 2359, 1618, 1583, 1568, 1525, 1450, 1416, 1373,
1267, 1201, 1097, 1061, 1036, 1001 cmÀ1; HRMS (ESI+) m/z calcd
for C18H15BrClN4 (M+H)+: 401.0163, found: 401.0163; Anal. Calcd
for C18H14BrClN4; C, 53.82; H, 3.51; N, 13.95. Found: C, 53.66; H,
3.50; N, 13.75.
The test compound in DMSO (final 1%) was added to 15 mg/mL
microsome in 100 mM Tris–HCl at pH 8.0, 5 mM EDTA, 500 mM
phenol, 1 mM GSH, 10 mM Hematin. The microsome was prepared
from mPGES-1 and COX-1 co-transfected HEK293 cells. Next, the
mixture was pre-incubated at room temperature for 30 min. The
reaction was started by the addition of 12.5 mM arachidonic acid
dissolved in 0.1 M KOH. The reaction mixture was incubated at
room temperature for 60 min. The reaction was stopped by addi-
tion of 1 M HCl. The reaction mixture was neutralized by 1 M
NaOH and PGE2 levels were measured by HTRF. The IC50 values
were calculated by a logistic regression method.14
4.1.22. 7-Bromo-2-(2-chlorophenyl)-4-(methylthio)-
imidazo[4,5-c]quinoline (24)
A mixture of 7 (50.0 mg, 0.127 mmol) and sodium thiomethox-
ide (NaSMe, 50.8 mg, 0.635 mmol) in NMP (1.0 mL) was stirred at
80 °C for 1 h under microwave irradiation. After cooling to room
temperature, water and AcOEt were added. The mixture was ex-
tracted with AcOEt twice, and the combined extracts were washed
with water and brine, dried over Na2SO4. After filtrated, the solvent
was removed in vacuo. The residue was purified by silica gel col-
umn chromatography (CHCl3/MeOH = 30:1) and triturated with
AcOEt to afford 24 (41.0 mg, 80%) as a white solid. 1H NMR
(DMSO-d6, 300 MHz) d 14.06 (0.7H, s), 8.27 (1H, d, J = 8.6 Hz),
8.18 (1H, d, J = 1.3 Hz), 7.85 (1H, dd, J = 1.7, 7.0 Hz), 7.69–7.75
(2H, m), 7.53–7.64 (2H, m), 2.72 (3H, s); 13C NMR (DMSO-d6,
75 MHz) d 154.7, 148.8, 144.5, 135.1, 132.8, 132.4, 132.1, 131.8,
130.3, 130.1, 129.5, 128.0, 127.6, 123.7, 120.4, 115.0, 11.2; mp
Acknowledgment
We are grateful to Ms. Keiko Bando for performing the elemen-
tal analysis, and Ms. Mai Tada for recording HRMS spectra, and Dr.
Yoshiaki Isobe for his support and encouragement.
References and notes
1. Iyer, J. P.; Srivastava, P. K.; Dev, R.; Dastidar, S. G.; Ray, A. Expert Opin. Ther.
Targets 2009, 13, 849.
2. Funk, C. D. Science 1871, 2001, 294.
214–215 °C; IR (ATR)
m 3433, 2929, 2360, 1620, 1568, 1497,
1452, 1443, 1362, 1308, 1286, 1257, 1234, 1207, 1194, 1055,
1036 cmÀ1; HRMS (ESI+) m/z calcd for C17H12BrClN3S (M+H)+:
403.9618, found: 403.9611; Anal. Calcd for C17H11BrClN3S; C,
50.45; H, 2.74; N, 10.38. Found: C, 50.52; H, 2.78; N, 10.37.
3. (a) Watanabe, K.; Kurihara, K.; Suzuki, T. Biochem. Biophys. Acta 1999, 1438,
406; (b) Tanioka, T.; Nakatani, Y.; Semmyo, N.; Murakami, M.; Kudo, I. J. Biol.
Chem. 2000, 275, 32775.
4. Murakami, M.; Naraba, H.; Tanioka, T.; Semmyo, N.; Nakatani, Y.; Kojima, F.;
Ikeda, T.; Fueki, M.; Ueno, A.; Oh-ishi, S.; Kudo, I. J. Biol. Chem. 2000, 275, 32783.
5. (a) Trebino, C. E.; Stock, J.; Gibbons, C. P.; Naiman, B. M.; Wachtmann, T. S.;
Umland, J. P.; Pandher, K.; Lapointe, J. M.; Saha, S.; Roach, M. L.; Carter, D.;
Thomas, N. A.; Durtschi, B. A.; McNeish, J. D.; Hambor, J. E.; Jakobsson, P. J.;
Carty, T. J.; Perez, J. R.; Audoly, L. P. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 9044;
(b) Kamei, D.; Yamakawa, K.; Takegoshi, Y.; Mikami-Nakanishi, M.; Nakatani,
Y.; Oh-ishi, S.; Yasui, H.; Azuma, Y.; Hirasawa, N.; Ohuchi, K.; Kawaguchi, H.;
Ishikawa, Y.; Ishii, T.; Uematsu, S.; Akira, S.; Murakami, M.; Kudo, I. J. Biol. Chem.
2004, 279, 33684; (c) Mabuchi, T.; Kojima, H.; Abe, T.; Takagi, K.; Sakurai, M.;
Ohmiya, Y.; Uematsu, S.; Akira, S.; Watanabe, K.; Ito, S. Neuroreport 2004, 15,
1395.
6. (a) Samuelsson, B.; Morgenstern, R.; Jakobsson, P. J. Pharmacol. Rev. 2007, 59,
207; (b) Chaudhry, U. A.; Zhuang, H.; Crain, B. J.; Doré, S. Alzheimers Demen.
2008, 4, 6; (c) Kihara, Y.; Matsushita, T.; Kita, Y.; Uematsu, S.; Akira, S.; Kira, J.;
Ishii, S.; Shimizu, T. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 21807.
7. (a) Côté, B.; Boulet, L.; Brideau, C.; Claveau, D.; Ethier, D.; Frenette, R.; Gagnon,
M.; Giroux, A.; Guay, J.; Guiral, S.; Mancini, J.; Martins, E.; Massé, F.; Méthot, N.;
Riendeau, D.; Rubin, J.; Xu, D.; Yu, H.; Ducharme, Y.; Friesen, R. W. Bioorg. Med.
Chem. Lett. 2007, 17, 6816; (b) Giroux, A.; Boulet, L.; Brideau, C.; Chau, A.; Claveau,
4.1.23. 7-Bromo-2-(2-chlorophenyl)-4-(ethylthio)-imidazo[4,5-
c]quinoline (25)
The title compound 25 was synthesized in 94% yield from 7
using sodium thioethoxide (NaSEt) according to the procedure to
prepare 24. 1H NMR (DMSO-d6, 300 MHz) d 14.06 (0.6H, s), 8.27
(1H, d, J = 8.6 Hz), 8.15 (1H, d, J = 1.7 Hz), 7.85 (1H, dd, J = 1.9,
7.1 Hz), 7.69–7.75 (2H, m), 7.53–7.64 (2H, m), 3.40 (2H, q,
J = 7.3 Hz), 1.41 (3H, t, J = 7.3 Hz); 13C NMR (DMSO-d6, 75 MHz) d
149.0, 144.5, 132.4, 132.2, 131.8, 130.4, 130.1, 129.5, 128.0,
127.6, 123.7, 120.4, 22.4, 14.9; mp 129–133 °C (dec); IR (ATR)
2927, 2362, 1703, 1624, 1560, 1491, 1473, 1429, 1360, 1309,
1263, 1190, 1066, 1053 cmÀ1
HRMS (ESI+) m/z calcd for
18H14BrClN3S (M+H)+: 417.9775, found: 417.9769; Anal. Calcd
m
;
C

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T. Shiro et al. / Bioorg. Med. Chem. 21 (2013) 2068–2078
D.; Côté, B.; Ethier, D.; Frenette, R.; Gagnon, M.; Guay, J.; Guiral, S.; Mancini, J.;
10. (a) Gerster, J. F.; Lindstrom, K. J.; Miller, R. L.; Tomai, M. A.; Birmachu, W.;
Bomersine, S. N.; Gibson, S. J.; Imbertson, L. M.; Jacobson, J. R.; Knafla, R. T.;
Maye, P. V.; Nikolaides, N.; Oneyemi, F. Y.; Parkhurst, G. J.; Pecore, S. E.; Reiter,
M. J.; Scribner, L. S.; Testerman, T. L.; Thompson, N. J.; Wagner, T. L.; Weeks, C.
E.; Andre, J.-D.; Lagain, D.; Bastard, Y.; Lupu, M. J. Med. Chem. 2005, 48, 3481;
(b) Shukla, N. M.; Malladi, S. S.; Day, V.; David, S. A. Bioorg. Med. Chem. 2011, 19,
3801.
11. (a) Kuroda, T.; Fumio, S. Tetrahedron Lett. 1991, 32, 6915; (b) Suzuki, F.; Kuroda,
T.; Nakasato, Y.; Manabe, H.; Ohmori, K.; Kitamura, S.; Ichikawa, S.; Ohno, T. J.
Med. Chem. 1992, 35, 4045.
12. (a) Khanna, I. K.; Weier, R. M. Tetrahedron Lett. 1885, 1993, 34; (b) Arico, J. W.;
Calhoun, A. K.; Salandria, K. J.; McLaughlin, L. W. Org. Lett. 2010, 12, 120.
13. He, S.; Lai, L. J. Chem. Inf. Model. 2011, 51, 3254.
14. Takahashi, H.; Nagata, H.; Shiro, T.; Kase, H.; Tobe, M.; Shimonishi, M.;
Hiramatsu, R. presented in part at the 2nd Society for Laboratory Automation and
Screening, ORLAND, 2013.
Martins, E.; Massé, F.; Méthot, N.; Riendeau, D.; Rubin, J.; Xu, D.; Yu, H.;
Ducharme, Y.; Friesen, R. W. Bioorg. Med. Chem. Lett. 2009, 19, 5837; (c) Wang, J.;
Limburg, D.; Carter, J.; Mbalaviele, G.; Gierse, J.; Vazquez, M. Bioorg. Med. Chem.
Lett. 2010, 20, 1604; (d) Chiasson, J.-F.; Boulet, L.; Brideau, C.; Chau, A.; Claveau,
D.; Côté, B.; Ethier, D.; Giroux, A.; Guay, J.; Guiral, S.; Mancini, J.; Massé, F.;
Méthot, N.; Riendeau, D.; Roy, P.; Rubin, J.; Xu, D.; Yu, H.; Ducharme, Y.; Friesen, R.
W. Bioorg. Med. Chem. Lett. 2011, 21, 1488; (e) Waltenberger, B.; Wiechmann, K.;
Bauer, J.; Markt, P.; Noha, S. M.; Wolber, G.; Rollinger, J. M.; Werz, O.; Schuster, D.;
Stuppner, H. J. Med. Chem. 2011, 54, 3163; (f) Wiegard, A.; Hanekamp, W.;
Griessbach, K.; Fabian, J.; Lehr, M. Eur. J. Med. Chem. 2012, 48, 153.
8. Jegersch€old, C.; Paweizik, S. C.; Purhonen, P.; Bhakat, P.; Gheorghe, K. R.;
Gyobu, N.; Mitsuoka, K.; Morgenstern, R.; Jakobsson, P. J.; Hebert, H. Proc. Natl.
Acad. Sci. U.S.A. 2008, 105, 11110.
9. Shiro, T.; Takahashi, H.; Kakiguchi, K.; Inoue, Y.; Masuda, K.; Nagata, H.; Tobe,
M. Bioorg. Med. Chem. Lett. 2012, 22, 285.