Discovery and structure-activity relationship study of 4-phenoxythiazol-5-carboxamides as highly potent TGR5 agonists

Article abstract of DOI:10.1248/cpb.c15-00905

A novel therapy that stimulates endogenous glucagon-like peptide-1 (GLP-1) secretion by Takeda G-protein-coupled receptor 5 (TGR5) agonists might be a superior alternative for the treatment of type 2 diabetes mellitus. A series of 4-phenoxythiazol-5-carboxamides were developed as highly potent TGR5 agonists using a bioisosteric replacement strategy based on the scaffold of 4-phenoxynicotinamides. The structure-activity relationship on the bottom phenyl ring and the thiazole ring was extensively studied, and the 2-methylthiazole derivatives 30c and e displayed the best in vitro potency toward human TGR5, with EC₅₀ values of approximately 1 nM. While endowed with excellent in vitro potency, the 2-methyl-thiazoles were flawed with high microsomal clearance.

Full text of DOI:10.1248/cpb.c15-00905

326
Chem. Pharm. Bull. 64, 326–339 (2016)
Vol. 64, No. 4
Regular Article
Discovery and Structure–Activity Relationship Study of
4-Phenoxythiazol-5-carboxamides as Highly Potent TGR5 Agonists
,b
,b
Zhixiang Chen,a,b Mengmeng Ning,b Qingan Zou,b Hua Cao,b Yangliang Ye,* Ying Leng,* and
Jianhua Shenb
a College of Pharmacy, Nanchang University; Nanchang 330006, China: and b State Key Laboratory of Drug
Research, Shanghai Institute of Materia Medica (SIMM), Chinese Academy of Sciences; Shanghai 201203, China.
Received November 14, 2015; accepted January 14, 2016; advance publication released online February 4, 2016
A novel therapy that stimulates endogenous glucagon-like peptide-1 (GLP-1) secretion by Takeda G-pro-
tein-coupled receptor 5 (TGR5) agonists might be a superior alternative for the treatment of type 2 diabetes
mellitus. A series of 4-phenoxythiazol-5-carboxamides were developed as highly potent TGR5 agonists using
a bioisosteric replacement strategy based on the scaffold of 4-phenoxynicotinamides. The structure–activ-
ity relationship on the bottom phenyl ring and the thiazole ring was extensively studied, and the 2-methyl-
thiazole derivatives 30c and e displayed the best in vitro potency toward human TGR5, with EC50 values of
approximately 1nM. While endowed with excellent in vitro potency, the 2-methyl-thiazoles were flawed with
high microsomal clearance.
Key words Takeda G-protein-coupled receptor 5 agonist; bioisostere; microsomal clearance; structure–
activity relationship
Takeda G-protein-coupled receptor 5 (TGR5), also known clinical trial phase, and most are still in the discovery phase,
as G-protein coupled bile acid receptor 1 (GPBAR1), is a cell because of a lack of appropriate Pharmacokinetic/Pharma-
surface receptor responsive to bile acids. It has been found codynamic (PK/PD) profiles, or having side effects such as
to be ubiquitously expressed in animal and human tissues, stimulating filling of the gallbladder,22,23) or causing changes
including the liver, intestine, heart, spleen, skeletal muscle, in heart rate and blood pressure.18) Therefore, the search for
brown adipose tissue, gallbladder and brain.1–4) It is thought to a greater variety of promising TGR5 agonists with potent in
play an important role in the regulation of energy homeostasis vitro activity to expand the chemical library of TGR5 agonists
and glucose metabolism. Activation of the TGR5 receptor by still represents a very urgent need, and further optimizations
bile acids triggers an increase in energy expenditure in brown based on such agonists could increase the possibility of pro-
adipose tissue and skeletal muscle.5) More importantly, TGR5 ducing drug candidates with good in vivo potency and low
activation also promotes glucagon-like peptide-1 (GLP-1) se- side-effects.
cretion in the intestine.6) As a member of the incretin family,
In our initial efforts to find novel TGR5 agonists, a scaf-
GLP-1 acts as an important physiological regulator in glucose fold of 4-phenoxynicotinamide (Fig. 2, scaffold A) was devel-
control via several mechanisms of action.7) But endogenous oped.22) Using this scaffold as a basis, most of our previous
GLP-1 is significantly limited as a direct drug for the treat- structural explorations were focused on the upper tetrahydro-
ment of type 2 diabetes because of its rapid inactivation in quinoxaline region and the bottom phenyl ring,22,24) whereas
plasma by dipeptidyl peptidase-4 (DPP-4). There are two main few explorations were carried out at the central core part,
classes of alternative GLP-1-based drugs being widely used in which was previously thought of as a limited region to alter.
a clinical setting: DPP-4 inhibitors and DPP-4-resistant GLP-1 For this work, we investigated whether these alterations at
receptor (GLP-1R) agonists.8) However, these drugs may not the central core part would generate additional potent TGR5
be able to halt the progression of type 2 diabetes because they agonists for further studies. First, we compared scaffold A
all exert their actions through increasing the plasma concen- with the scaffolds of other reported small molecular TGR5
tration of “GLP-1R agonists,” and they thus may lack some agonists, and observed that scaffold A was very similar to the
of the local actions that endogenous GLP-1 is likely to have.9) scaffolds of 5–8, with a five or six-membered heteroaromatic
Therefore, a novel therapy that stimulates endogenous GLP-1 ring as a core part, one phenyl ring or heteroaromatic ring
secretion by TGR5 agonists is considered as a superior alter- linked to the core via an amide bond, and another phenyl
native for the treatment of type 2 diabetes mellitus.
ring linked to the core directly or via oxygen. We therefore
In recent years, many different kinds of TGR5 agonists hypothesized that replacing the pyridine of scaffold A with
have been reported (Fig. 1). Structurally, TGR5 agonists can five-membered heteroaromatic rings using a bioisosteric re-
fall into two categories. The first category is bile acid deriva- placement strategy was likely to yield other TGR5 agonists
tives,10–12) such as lithocholic acid (LCA) and 6α-ethyl-23(S)- with equivalent or even better potency (Fig. 2). To explore
methylcholic acid (INT-777). The second category is non-bile other scaffold that met our requirement, pyrazoles, 1,2,3-tri-
acid derivatives, including naturally occurring non-bile acid azoles and 2-methyl-thiazoles were designed and synthesized.
agonists such as oleanolic acid and betulinic acid,13,14) and Herein, we describe our efforts in the synthesis, biological
synthetic small molecular TGR5 agonists.15–22) However, only evaluations and structure–activity relationship (SAR) studies
one compound (SB-756050) has ever been advanced into the of this series of TGR5 agonists.
*To whom correspondence should be addressed. e-mail: ylye@simm.ac.cn; yleng@simm.ac.cn
© 2016 The Pharmaceutical Society of Japan

Vol. 64, No. 4 (2016)
Chem. Pharm. Bull.
327
Fig. 1. Selected TGR5 Agonists Reported in the Literature and Patent
Fig. 2. Design of Other TGR5 Agonists for Further Studies Using a Bioisosteric Replacement Strategy
Reagents and conditions: (a) various substituted or unsubstituted phenols, KOH, DMF, 100°C; (b) NaClO2, NaH2PO4, tBuOH, THF, H2O; (c) (COCl)2, DMF, DCM,
t
reflux; (d) 1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline, Et3N, DCM, r.t.; (e) CuCl2, BuONO, MeCN, 60°C; (f) various substituted or unsubstituted phenols, K2CO3, DMF,
120°C; (g) NaOH, 1,4-dioxane, H2O, r.t.
Chart 1. The Synthesis of Pyrazoles
and 18a–c.
Chemistry
The synthesis of pyrazole derivatives 13a–d and 18a–c are
The synthesis of 1,2,3-triazole derivatives is outlined in
elucidated in Chart 1. Nucleophilic substitution on 3-chloro- Chart 2. First, compound 19 was synthesized using a method
pyrazole (10) with commercially available phenols afforded described in the literature,26) followed by treatment with phos-
the aldehydes 11a–d, which were subsequent oxidized with phorus pentachloride, which yielded compound 20.27) Next,
sodium chlorite to give the key intermediates 12a–d. In the chlorine derivative 20 reacted with substituted phenols in
contrast, 3-aminopyrazole (14) was transformed into a chlo- the presence of sodium hydride to provide the diaryl ethers
rine derivative (15) through diazotization in the presence 21a-b. Through hydrolysis with sodium hydroxide and con-
of cupric chloride. Nucleophilic substitution with commer- densation with 1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline or
cially available phenols and hydrolysis with sodium hydrox- 1-methyl-1,2,3,4-tetrahydroquinoxaline, the key intermediates
ide generated the key intermediates 17a–c. Finally, the acids 23a and b and 24a and b were obtained. In addition, deprotec-
12a–d and 17a–c were condensed with 1-cyclopropyl-1,2,3,4- tion of compounds 24a and b gave the target compounds 25a
tetrahydroquinoxaline25) to give the title compounds 13a–d and b, whereas deprotection of compounds 23a and b was not

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Chem. Pharm. Bull.
Vol. 64, No. 4 (2016)
Reagents and conditions: (a) PCl5, toluene, 0°C to r.t.; (b) various substituted phenols, NaH, DMF, 0 to 85°C; (c) NaOH, 1,4-dioxane, H2O, r.t.; (d) (COCl)2, DMF, DCM,
reflux; (e) 1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline or 1-methyl-1,2,3,4-tetrahydroquinoxaline, Et3N, DCM, r.t.; (f) TFA, 65°C.
Chart 2. The Synthesis of 1,2,3-Triazoles
Reagents and conditions: (a) EtONa, EtOH; (b) substituted or unsubstituted o-fluoronitrobenzene, NMP, Microwave 125°C; (c) Fe, NH4Cl, THF, H2O; (d) tBuONO,
CuCl2, MeCN, r.t.–60°C; (e) tBuONO, CuBr2, MeCN, r.t.–60°C; (f) tBuONO, MeCN, reflux; (g) NaOH, 1,4-dioxane, H2O, r.t.; (h) (COCl)2, DMF, DCM, reflux; (i)
1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline or 1-methyl-1,2,3,4-tetrahydroquinoxaline, Et3N, DCM, r.t.; (j) Zn(CH3)2, PdCl2(dppf)·CH2Cl2, 1,4-dioxane, 80°C; (k)
PdCl2(dppf)·CH2Cl2, bis(pinacolato)diboron, KOAc, 1,4-dioxane, 130°C; (l) H2O2, THF, 0°C–r.t.
Chart 3. The Synthesis of 2-Methyl-thiazoles
Reagents and conditions: (a) EtOH, reflux; (b) EtONa, EtOH; (c) 4-chloro-2-fluoro-1-nitrobenzene, NMP, Microwave 125°C; (d) Fe, NH4Cl, THF, H2O; (e) tBuONO,
t
CuCl2, MeCN, r.t.–60°C; (f) BuONO, MeCN, reflux; (g) NaOH, 1,4-dioxane, H2O, r.t.; (h) (COCl)2, DMF, DCM, reflux; (i) 1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline,
Et3N, DCM, r.t.
Chart 4. The Synthesis of Thiazoles 37a–h
completed because of the unstable N-cyclopropyl group.
tion with bis(pinacolato)diboron and subsequent oxidation
The synthesis of 2-methyl-thiazole derivatives is shown in with hydrogen peroxide. In addition, direct hydrolysis of the
Chart 3. This started with compound 26, which was prepared intermediates 27a and b and subsequent condensation with
according to the procedure described in a patent,28) followed 1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline yielded 32a and b.
by formation of a sodium salt and immediate treatment with
The synthesis of other thiazoles 37a–h that were substituted
various o-fluoronitrobenzenes under microwave assistance; with ethyl, isopropyl, phenyl or 2-pyridyl groups on the thia-
this gave the key intermediates 27a–e. Next, reduction of zole ring is show in Chart 4, which is similar to the protocols
the nitros 27a–e to aminos 28a–e, and subsequent diazotiza- for preparation of 2-methyl-thiazole derivatives 30c and i.
tion with tert-butyl nitrite in the presence of cupric chloride,
cupric bromide or direct reflux, produced the intermediates
Results and Discussion
29a–j. Finally, via hydrolysis with sodium hydroxide and con-
The newly-synthesized pyrazoles, 1,2,3-triazoles and
densation as described above, the desired compounds 30a–n 2-methyl-thiazoles were evaluated for their activity as agonists
were obtained. Analogs 31a–c were prepared from 30e, g against human TGR5 (hTGR5) using a cAMP-responsive ele-
and n via the Negishi cross-coupling reaction.29) Analog 31d ment (CRE)-driven luciferase assay in HEK293 cells.22,24,30,31)
was prepared through a PdCl2(dppf)·CH2Cl2-catalyzed reac- Compounds with EC50 values against hTGR5 of less than

Vol. 64, No. 4 (2016)
Chem. Pharm. Bull.
329
Table 1. In Vitro Activity of the Pyrazoles 13a–d and 18a–c
Table 3. In Vitro Activity of the 2-Methyl-thiazoles 30a–m, 31a and b
and 32a and b
Compound
R1
R2
hTGR5 EC50 (nM)a)
hTGR5 EC50 mTGR5 EC50
13a
13b
13c
13d
18a
18b
18c
H
Me
Me
Me
Me
H
NA
NA
Compound
R1
R2
(nM)a)
(nM)b)
2,5-diCl
2,5-diMe
3-OMe
H
NA
INT-777
30a
30b
30c
30d
30e
30f
—
—
1226 357
1.4 0.22
9.1 2.0
1.1 0.07
8.2 1.5
0.97 0.15
6.0 1.0
1.2 0.27
11 1.8
358 77
65 3.7
484 87
71 3.3
563 29
72 15
NA
2-Cl-5-Me
2-Cl-5-Me
2,5-diCl
cPr
Me
cPr
Me
cPr
Me
cPr
Me
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
cPr
NA
2,5-diMe
3-OMe
H
NA
H
129nM
2,5-diCl
2-Br-5-Cl
2-Br-5-Cl
2-Br-5-Me
2-Br-5-Me
5-Cl-2-Me
2,5-diMe
5-Cl-2-NO2
5-Me-2-NO2
2-Cl
a) hTGR5 EC50 values given are the means of at least two independent experi-
ments; NA: no measurable activity at a concentration of 0.1µM with two independent
experiments.
499 35
67 4.8
479 80
141 0.28
100 50
408 39
238 28
227 31
931 90
—
30g
30h
31a
31b
32a
32b
30m
30i
4.4 2.1
3.6 0.47
7.6 0.16
7.5 2.0
15 2.8
Table 2. In Vitro Activity of the Triazoles 23a and b, 24a and b and 25a
and b
3-Cl
31 5.4
30l
4-Cl
235 21
26 6.1
30j
3-Me
435 34
331 68
200 59
106 40
85 6.3
30k
30n
31c
31d
2,4-diCl
11 0.22
2.8 0.42
1.5 0.40
1.4 0.31
4-Br-2,5-diCl
2,5-diCl-4-Me
2,5-diCl-4-OH
Compound
R1
R2
R3
hTGR5 effecta)
23a
23b
24a
24b
25a
25b
2,5-diCl
3-OMe
2,5-diCl
3-OMe
2,5-diCl
3-OMe
cPr
cPr
Me
Me
Me
Me
PMB
PMB
PMB
PMB
H
NA
NA
NA
NA
NA
NA
a) EC50 values of hTGR5 are expressed as the mean S.D. of at least three inde-
pendent experiments. b) EC50 values of mTGR5 are expressed as the mean S.D. of
at least two independent experiments.
18c was not sufficient for further studies, and as a result we
discontinued exploration of the pyrazole scaffold.
The in vitro activity of 1,2,3-triazoles is shown in Table 2.
It was disappointing that the intermediates 23a and b and 24a
and b did not show any measureable activity at a concentra-
H
a) NA: no measurable activity at a concentration of 0.1µM with two independent
experiments.
100 nM were then selected for the mouse TGR5 (mTGR5) ac- tion of 0.1µM; neither did compounds 25a and b. We speculat-
tivity test. The results are shown in Tables 1–3. ed that the presence of a hydrogen bond donor at the triazole
As shown in Table 1, the 5-methylpyrazoles were designed ring of compounds 25a and b might be extremely unfavorable
and prepared first. Compound 13a (with no substituent on the for binding with the receptor, and the p-methoxybenzyl group
bottom phenyl ring) showed no measurable activity of hTGR5 on the triazole ring of compounds 23a and b and 24a and b
at a concentration of 0.1µM. Introduction of electron-with- was so large that it might result in a big change of the spatial
drawing 2,5-dichloro (13b), electron-donating 2,5-dimethyl configuration between the bottom phenyl ring and the middle
(13c) or 3-methoxyl (13d) group, also did not result in any triazole ring compared with the pyrazole derivative 18c.
promising activity. We hypothesized that the repulsive interac-
As shown in Table 3, the 2-methyl-thiazole series exhib-
tion between the methyl substituent on position 5 of pyrazole ited a dramatic improvement, especially for hTGR5 activity.
(compounds 13a–d) and the upper phenyl ring might cause a To carry out preliminary screening of the 2-methyl-thiazole
relatively great change of the spatial configuration between scaffold, the introductions of two substituents selected from
the upper phenyl ring and the middle core ring compared with a methyl, chloro or bromo moiety to the 2,5-di-positions of
scaffold A. Following removal of the 5-methyl substituent the bottom phenyl ring and a cyclopropyl or methyl group to
from the pyrazole ring, a series of 5-hydropyrazole deriva- the R2 region gave the desired compounds 30a–h. Of these
tives (18a–c) with similar substituents on the bottom phenyl compounds, 30a, c, e and g were significantly more potent
ring were synthesized and evaluated in vitro. As anticipated, than the corresponding compounds with a methyl group in the
a great improvement in the in vitro potency was observed. R2 region, and all displayed extremely high potency toward
Compound 18c with a 3-methoxyl substituent on the bottom hTGR5 in vitro, with EC50 values of approximately 1nM.
phenyl ring exhibited moderate agonist activity, with a hEC50
Next, we selected the R2 region with a cyclopropyl group
value of 129nM. However, the in vitro potency of compound into a subsequent library to further explore the SAR of the

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Chem. Pharm. Bull.
Vol. 64, No. 4 (2016)
Table 4. In Vitro Activity and C log P Values of the Thiazoles 37a–h
Table 5. In Vitro Metabolic Stability of Representative Thiazoles
CLint in vitro
(mL/min/g)
hTGR5 EC50
mTGR5 EC50
Compound
R
Species
T1/2 (min)
Compound
R1
R2
(nM)a)
(nM)b)
30a
2-Cl-5-Me
Human
Mouse
Human
Mouse
Human
Mouse
Human
Mouse
Human
Mouse
Human
Mouse
1.1
1.6
1.2
2.7
1.4
2.8
1.3
2.2
1.0
1.6
1.2
3.7
1893
1297
1698
780
30c
37a
37b
37c
37d
37e
37f
Methyl
Ethyl
Cl
Cl
H
1.1 0.07
32 6.2
71 3.3
2137 317
—
30c
30e
30g
31b
32b
2,5-diCl
2-Br-5-Cl
2-Br-5-Me
2,5-diMe
Ethyl
185 74
242 71
2817 110
6.9 2.3
57 19
Isopropyl
Isopropyl
Phenyl
Cl
H
—
1453
762
—
Cl
H
1865 252
>5000
746 7.0
>5000
1678
959
Phenyl
37g
37h
2-Pyridyl
2-Pyridyl
Cl
H
4.4 1.2
61 23
2027
1341
1783
569
a) EC50 values of hTGR5 and mTGR5 are expressed as the mean S.D. of at least
three independent experiments. b) EC50 values of hTGR5 and mTGR5 are expressed
as the mean S.D. of at least three independent experiments.
5-Me-2-NO2
bottom phenyl region. Replacement of the 2-chloro of com-
pounds 30a and c with a weak electron-donating methyl group the plane of thiazole ring, whereas part of the ethyl group of
(analogs 31a, b) led to a 3−4-fold decrease of the hEC50 and compound 37a and the isopropyl group of compound 37c were
a slight decrease of the mEC50, and resulted in more reduction observed outside of the plane of thiazole ring. This observa-
with an electron-withdrawing nitro group (compounds 32a, tion suggested that the substitutions outside of the plane of the
b). In addition, removal of the 2-chloro of compound 30a pro- thiazole ring were not tolerated for high binding affinity, and
vided analog 30j, which exhibited only moderate activity on which might disturb the postulated π–π stacking interaction
hTGR5. Another key finding was that the in vitro activity of between the thiazole ring and the receptor of hTGR5. Due to
compounds 30c, i, k–m, which were substituted with a single the fact that the human TGR5 receptor shares only 83% amino
chloro group or two chloro groups at different positions, acid identity with mouse TGR5 receptor,10) the in vitro activity
followed the order 4-Cl
≪3-Cl<2-Cl<2,4-diCl≪2,5-diCl, of all thiazole derivatives on mTGR5 was significantly weaker
indicating that the 2,5-di-substitution was the best favored. than that on hTGR5. In general, in vitro activity of the 2-sub-
Additionally, while keeping the 2,5-diCl groups intact, posi- stituted-thiazole derivatives follow the order that methyl>2-
tion 4 of compound 30c was also explored. It could be noted pyridyl>phenyl>ethyl>isopropyl.
that various substitutions at position 4 of compound 30c were
Finally, given the fact that many reported small molecule
well tolerated, such as bromo (30n), methyl (31c) and hydroxyl TGR5 agonists were found with poor metabolic stability pro-
(31d) substituents, which suggested that other groups might file, which severely limited their further development as orally
also be well tolerated.32) As a general rule, the 2-methyl- available agents, then some representative thiazoles were also
thiazole scaffold successfully maintained excellent in vitro selected to determine their metabolic clearance in human and
potency.
mouse liver microsomes (MLM). Unfortunately, the select
To further explore the SAR of the thiazole ring, a series thiazoles all exhibited extremely high intrinsic clearance in
of thiazole derivatives that were substituted with ethyl, iso- both human liver microsome (HLM) and MLM (Table 5),
propyl, phenyl or 2-pyridyl groups on the thiazole ring were especially for compound 31b (HLM CLint=2027mL/min/g,
designed and synthesized (Table 4). Consistent with the ob- T1/2=1.0min; MLM CLint=1341mL/min/g, T1/2=1.6min),
served SAR around the 2-methyl-thiazoles, the 2,5-dichloro which indicated that these compounds were deficient as tool
analogs of these series were much better than the correspond- compounds to investigate the therapeutic potential of systemic
ing 3-dichloro analogs. Among the 2,5-dichloro analogs, TGR5 agonists for the treatment of type 2 diabetes mellitus
compound 30c still displayed the best in vitro hTGR5 and due to their high metabolic clearance.
mTGR5 potency. Interestingly, replacement of the methyl of
compound 30c with ethyl (compound 37a) or isopropyl (com-
pound 37c) resulted in a sharp decrease of potency on hTGR5,
Conclusion
In summary, a series of 4-phenoxythiazol-5-carboxamides
but only caused a slight loss with phenyl (compound 37e, were developed as highly potent TGR5 agonists using a
hEC50=6.9nM) or 2-pyridyl (compound 37g, hEC50=4.4nM). bioisosteric replacement strategy based on scaffold A, and
To explain this result, the preferred conformations of com- extensive SAR explorations were described. Due to extremely
pounds 30c, 37a, c, e and g were predicted in the software of high metabolic clearance, this series were insufficient as sys-
ChemBio3D Ultra 14.0 using the MM2 algorithm. The methyl temically targeted tool compounds. Considering that systemic
group of compound 30c, the phenyl group of compound 37e TGR5 agonists that exposed to the gallbladder and heart were
and the 2-pyridyl group of compound 37g were observed at thought likely to result unfavorable side effects, and that

Vol. 64, No. 4 (2016)
Chem. Pharm. Bull.
331
making TGR5 agonists with low systemic exposure had the performed in a Biatage Inititor. Melting point of target com-
potential to minimize the side effects, our additional efforts pounds was measured by SGWX-4 melting point apparatus
are ongoing to determine if they can be used for intestinal (Shanghai Precision and Scientific Instrument Corporation,
1
targeting with limited systemic exposure combined with other Shanghai, China). H- and 13C-NMR spectra were recorded
medicinal chemistry strategies, such as introducing polar, hy- on a Bruker AC300 or a Bruker AC400 or a Bruker AC500
drophilic groups to the position 4 of the bottom phenyl ring to NMR spectrometer, using tetramethylsilane (TMS) as an in-
1
reduce their absorption.
ternal reference. H-NMR date are reported as multiplicity (s
singlet, d doublet, t triplet, q quarter, dd doublet of doublets,
dt doublet of triplets, brs broad singlet, m multiplet), num-
Experimental
In Vitro TGR5 Assay hTGR5/CRE/HEK293 or mTGR5/ ber of protons, and coupling constant in hertz (Hz). Spectra
CRE/HEK293 stable cell line was obtained by transfection were carried in CDCl3, DMSO-d6, and CD3OD. IR spectra
of HEK293 cells with human or mouse TGR5 expression were recorded on IS5 FT-IR (Thermo). Low-resolution mass
plasmid (hTGR5-pcDNA3.1 or mTGR5-pcDNA3.1) and CRE- spectra were determined on an Agilent LC-MS systems that
driven luciferase reporter plasmid (pGL4.29; Promega, Madi- consisted of an Agilent 1260 infinity LC coupled to an Agilent
son, WI, U.S.A.), and employed to assess the activity of test 6120 Quadrupole mass spectrometer (electrospray ionization
compounds by reporter gene assay. Briefly, cells were seeded (ESI)+) using an Agilent (Symmetry® C18 Colum, 3.5µm,
into 96-well plates and incubated overnight in Dulbecco’s 2.1×50mm) with aqueous CH3CN (0.4mL/min, 0–5min,
modified Eagle’s medium (DMEM) supplemented with 10% 30–90%; 5–9min, 90–90%) containing 0.1% formic acid and
fetal bovine serum (FBS) in 5% CO2 at 37°C. Then, cells were monitored at λ 240nm. High-resolution (HR) mass spectra
incubated with fresh medium containing different concentra- were recorded on a Q-TOF Ultima Globe mass spectrameter
tions of test compounds or 20µM INT-777 as a positive control (Micromass, Manchester, U.K.).
for 5.5h. Luciferase activity in cell lysate was determined
5-(2,5-Dimethylphenoxy)-1,3-dimethyl-1H-pyrazole-
using the Steady-Glo Luciferase Assay System (Promega) ac- 4-carbaldehyde (11c) Compound 10 (500mg, 3.15mmol)
cording to the manufacturer’s instructions. Compounds with was dissolved in N,N-dimethylformamide (DMF) and treated
EC50 values on human TGR5 (hTGR5) less than 100nM were with excess 2,5-dimethylphenol (1.15g, 9.43mmol) and potas-
selected for the mouse TGR5 (mTGR5) activity test.
sium hydroxide (KOH) (270mg, 4,82mmol), then the reaction
In Vitro Microsomal Assay for Metabolic Stability The mixture was stirred at 120°C for 2h. After consumption of
test compound was dissolved in dimethyl sulfoxide (DMSO) 10 as monitored by TLC, the mixture was cooled to room
and diluted to the desired concentration with DMSO and temperature, then poured into water and extracted three times
0.1% aqueous bovine serum albumin (BSA). Human or mouse with EtOAc. The combined organic phases were washed with
liver microsomes were incubated in a 96-well plate contain- brine (3×), dried over MgSO4, filtered, and concentrated to
ing 0.1M Tris buffer (pH 7.4), 0.33mg/mL microsomal pro- dryness. The residue was purified by flash column chromatog-
1
tein, 0.1µM test compound, 5.0mM MgCl2, 0.005% BSA, and raphy to give 11c (661mg, 86%). H-NMR (300MHz, CDCl3)
1.0 mM reduced nicotinamide adenine dinucleotide phosphate δ: 9.33 (1H, s), 7.13 (1H, d, J=5.7Hz), 6.89 (1H, d, J=5.7Hz,),
(NADPH). Incubations were conducted at 37°C for 60min. 6.53 (1H, s), 3.64 (3H, s), 2.45 (3H, s), 2.32 (3H, s), 2.24 (3H,
An aliquot was removed at each time point (0, 7, 17, 30, s).
60min) and the enzymatic reaction was stopped by protein
5-(2,5-Dimethylphenoxy)-1,3-dimethyl-1H-pyrazole-
precipitation in methanol. The loss of the test compound was 4-carboxylic Acid (12c) To a solution of 11c (0.62g,
determined by LC-MS/MS. The intrinsic clearance (CLint, mL/ 2.54mmol) in mixed of tertiary butanol (9mL), tetrahydro-
min/g microsomal protein) was calculated from the following furan (THF) (9mL) and H2O (3mL), was added NaH2PO4
equations.
(1.83g, 15.2mmol), NaClO2 (1.38g, 15.2mmol) and 2-methyl-
but-2-ene (4mL), and then allowed to stir at room temperature
(r.t.) for 3h. After completion of the reaction, the solvent was
removed by rotary evaporation, and the crude was suspended
in water. The precipitate was collected via filtration to yield
C =C0 ⋅ e(−kt)
C0: concentration at time 0; t: time (min); k: slope (min−1).
1
12c (0.60g, 92%). H-NMR (300MHz, DMSO) δ: 12.01 (1H,
1000×slope
br), 7.14 (1H, d, J=7.8Hz), 6.80 (1H, d, J=7.8Hz), 6.25 (1H, s),
3.52 (3H, s), 2.32 (3H, s), 2.28 (3H, s), 2.16 (3H, s).
CLint
=
P
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(5-(2,5-
dimethylphenoxy)-1,3-dimethyl-1H-pyrazol-4-yl)metha-
P: microsomal protein concentration (mg/mL).
Synthetic Materials and Methods Unless otherwise none (13c) To a solution of 12c (0.5g, 1.92mmol) in dry
noted, all materials were purchased from commercial sup- dichloromethane (DCM) was added oxalyl chloride (491µL,
pliers and used without further purification. All reaction 5.76mmol) and three drops DMF, and held at reflux for 2h.
yields were not optimized. Analytical TLC (0.15–0.2mm) and Then the reaction mixture was cooled to room tempera-
preparative TLC (0.4–0.5mm) were performed on HSGF254 ture and concentrated. The residue was re-dissolved in dry
(Yantai Jiangyou Company, Yantai, Shandong, China), com- DCM, 1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline (341mg,
pounds were visualized by UV light (254nm). Column chro- 1.92mmol) and Et3N (797µL, 5.76mmol) were added, and
matography was carried out on silica gel (200−300 mesh) or the reaction was stirred at r.t. overnight. After completion,
with pre-packed silica cartridges (4–40g) from Bonna-Agela the reaction was diluted with water and extracted with DCM
Technologies Inc. (Tianjin, China) and eluted with system of (3×). The combined organic phases were collected, washed
the Teledyne Isco CombiFlash Rf. Microwave reactions were with brine, dried over MgSO4, concentrated and purified by

332
Chem. Pharm. Bull.
Vol. 64, No. 4 (2016)
flash column chromatography to afford the title compound 14 (2.5g, 1.48mmol) to the mixture in portions. The reac-
13c (624mg) as an off-white solid in 78% yield. mp 124°C. tion was stirred at r.t. for 2h, and then heated at 60°C for 1h.
1H-NMR (300MHz, CDCl3) δ: 7.07 (1H, dd, J=0.9Hz, After completion as TLC monitored, the reaction mixture
6.3Hz), 6.99–6.94 (2H, m), 6.75 (2H, d, J=5.7Hz), 6.49 (1H, was cooled to r.t. and diluted with 2N aq. HCl, then extracted
dt, J=0.9, 6.0Hz), 6.40 (1H, s), 3.73 (2H, m), 3.49 (3H, s), 2.91 with DCM (3×). The combined phases were washed with
(2H, m), 2.30 (1H, m), 2.26 (3H, s), 2.20 (3H, s), 2.01 (3H, s), brine, dried over MgSO4, filtered, concentrated and purified
0.74 (2H, m), 0.45 (2H, m). 13C-NMR (126MHz, CDCl3) δ: by flash column chromatography to give 15 (2.08g) in 75%
1
162.07, 154.12, 148.23, 146.18, 139.16, 137.04, 131.01, 125.41, yield. H-NMR (300MHz, CDCl3) δ: 7.90 (1H, s), 4.30 (2H, q,
125.27, 123.82, 123.07, 122.55, 116.28, 113.34, 112.97, 103.61, J=5.4Hz), 3.86 (3H, s), 1.34 (3H, t, J=5.4 Hz).
48.36, 40.66, 34.15, 31.27, 21.12, 15.55, 13.62, 7.89. IR (KBr)
Ethyl-1-methyl-5-phenoxy-1H-pyrazole-4-carboxylate
cm−1: 1626.27, 1504.57, 1419.43, 1404.60, 1361.74, 738.51. (16a) In a microwave reaction vessel was combined 15
HPLC-MS: 5.66min, 417.3 (M+H+). HR-MS (ESI): m/z (300mg, 1.59mmol), phenol (300mg, 3.19mmol) and Cs2CO3
(M+H+) Calcd for C25H29O2N4: 417.2285. Found: 417.2275.
(1.52g, 4.66mmol) in DMF. The vessel was sealed and the
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(1,3- resulting mixture was heated at 120°C by microwave for
dimethyl-5-phenoxy-1H-pyrazol-4-yl)methanone (13a) 30min. Then the reaction mixture was cooled to r.t., quenched
The title compound 13a was prepared from 10 and phenol with water and extracted with EtOAc three times. The organic
according to a procedure similar to that described for the layer was collected, washed with brine, dried over MgSO4 and
1
preparation of the title compound 13c. mp 145°C. H-NMR filtered. After the solvent was removed, the crude was purified
(300MHz, CDCl3) δ: 7.24 (2H, t, J=6.0Hz), 7.13 (1H, d, by flash column chromatography to yield 16a (280mg, 72%).
J=5.7Hz), 7.05 (1H, d, J=5.7Hz), 7.00 (1H, d, J=6.3Hz), 1H-NMR (300MHz, CDCl3) δ: 7.92 (1H, s), 7.3 (2H, dt, J=2.1,
6.73 (2H, d, J=6.0Hz), 6.70 (1H, d, J=6.3Hz), 6.48 (1H, 7.2Hz), 7.10 (1H, dt, J=1.2, 7.2Hz), 6.89 (2H, m), 4.07 (2H, q,
t, J=5.7Hz), 3.72 (2H, m), 3.53 (3H, s), 2.85 (2H, m), 2.30 J=7.2Hz), 3.71 (3H, s), 1.03 (3H, t, J=7.2 Hz).
(1H, m), 2.28 (3H, s), 0.78 (2H, m), 0.51 (2H, m). 13C-NMR
1-Methyl-5-phenoxy-1H-pyrazole-4-carboxylic Acid (17a)
(126MHz, CDCl3) δ: 161.89, 156.36, 148.53, 145.96, 139.18, 16a (270mg, 1.10mmol) was dissolved in a solution of 1,4-di-
129.77, 125.41, 125.24, 123.45, 122.64, 116.24, 115.04, 112.76, oxane–H2O=2:1, and NaOH (88mg, 2.20mmol) was added.
103.29, 48.25, 40.50, 34.20, 31.25, 13.61, 7.99. IR (KBr) cm−1: The mixture was stirred at r.t. until consumption of 16a as
1621.84, 1502.90, 1489.58, 1411.74, 1400.72, 1320.10, 756.37. monitored by TLC, and then the solvent was removed. The
HPLC-MS: 4.93min, 389.3 (M+H+). HR-MS (ESI): m/z residue was re-dissolved in water, acidified with 2N aqueous
(M+H+) Calcd for C23H25O2N4: 389.1972. Found: 389.1965.
HCl to pH 3 and then the product precipitated out. The pre-
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(5-(2,5- cipitate was collected by filtration to afford 17a (227mg, 95%)
1
dichlorophenoxy)-1,3-dimethyl-1H-pyrazol-4-yl)methanone and was carried forward without further purification. H-NMR
(13b) The title compound 13b was obtained as a white solid (300MHz, DMSO) δ: 12.25 (1H, s), 7.85 (1H, s), 7.36 (2H, dd,
from 10 and 2,5-dichlorophenol according to the general pro- J=1.5, 7.5Hz), 7.12 (1H, dt, J=0.9Hz, 7.5Hz), 6.92 (2H, m),
1
cedure. mp 139°C. H-NMR (300MHz, CDCl3) δ: 7.15 (1H, d, 3.61 (3H, s).
J=7.8Hz), 7.00 (1H, dt, J=1.2, 7.8Hz), 6.72 (1H, d, J=7.8Hz),
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(1-meth-
6.62 (1H, d, J=8.7Hz), 6.49 (1H, t, J=7.8Hz), 6.30 (1H, d, yl-5-phenoxy-1H-pyrazol-4-yl)methanone (18a) The title
J=2.4Hz), 6.18 (1H, dd, J=2.4, 8.7Hz), 3.76 (2H, m), 3.52 compound 18a was prepared as an off-white solid from 17a
(3H, s), 3.02 (2H, m), 2.35 (1H, m), 2.22 (3H, s), 0.80 (2H, m), and 1-cyclopropyl-1,2,3,4-tetrahydroquinoxaline according to
0.55 (2H, m). 13C-NMR (126MHz, CDCl3) δ: 165.04, 161.57, a procedure similar to the preparation of 13c from 12c. mp
1
156.72, 151.78, 148.00, 145.43, 139.52, 133.40, 131.21, 125.81, 104°C. H-NMR (300MHz, CDCl3) δ: 7.54 (1H, s), 7.26 (2H,
124.49, 122.84, 120.85, 116.53, 116.00, 113.19, 48.91, 41.19, m), 7.15 (1H, d, J=8.1Hz), 7.08 (1H, d, J=7.5Hz), 7.02 (1H, d,
34.49, 31.26, 13.44, 7.98. HPLC-MS: 5.76min, 457.2 (M+H+). J=8.4Hz), 6.79 (1H, d, J=7.8Hz), 6.75 (2H, d, J=8.1Hz), 6.52
HR-MS (ESI): m/z (M+H+) Calcd for C23H23O2N4Cl2: (1H, d, J=7.5Hz), 3.74 (2H, t, J=5.4Hz), 3.60 (3H, s), 2.94
457.1193. Found: 457.1186.
(2H, t, J=5.4Hz), 2.31 (1H, m), 0.77 (2H, m), 0.52 (2H, m).
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(5-(3- 13C-NMR (126MHz, CDCl3) δ: 160.92, 156.47, 146.70, 140.20,
methoxyphenoxy)-1,3-dimethyl-1H-pyrazol-4-yl)metha- 139.36, 129.78, 125.67, 125.26, 123.50, 123.21, 116.29, 115.03,
none (13d) The title compound 13d was prepared from 10 112.86, 105.00, 48.34, 40.60, 34.61, 31.25, 7.97. HPLC-MS:
and 3-methoxyphenol following the general procedure. mp 4.84min, 375.3 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for
1
109°C. H-NMR (300MHz, CDCl3) δ: 7.15 (2H, m), 6.99 (1H, C22H23O2N4: 375.1816. Found: 375.1810.
t, J=8.1Hz), 6.71 (1H, d, J=7.5Hz), 6.61 (1H, m), 6.48 (1H,
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(5-(2,5-
m), 6.31 (2H, m), 3.77 (2H, m), 3.74 (3H, s), 3.52 (3H, s), 2.90 dimethylphenoxy)-1-methyl-1H-pyrazol-4-yl)methanone
(2H, m), 2.30 (1H, m), 2.25 (3H, s), 0.78 (2H, m), 0.50 (2H, m). (18b) The title compound 18b was obtained as a white solid
13C-NMR (126MHz, CDCl3) δ: 160.84, 157.34, 151.14, 148.44, from 15 according to the general procedure that prepara-
1
139.24, 130.30, 130.20, 125.40, 122.65, 116.24, 112.80, 109.02, tion of title compound 18a. mp 131°C. H-NMR (300MHz,
108.96, 107.13, 106.96, 101.78, 55.44, 48.26, 40.98, 34.22, CDCl3) δ: 7.52 (1H, s), 7.10 (1H, d, J=8.1Hz), 6.99 (2H, m),
31.20, 22.70, 13.60, 7.99. HPLC-MS: 4.99min, 419.3 (M+H+). 6.81 (1H, d, J=8.1Hz), 6.76 (1H, d, J=7.5Hz), 6.51 (1H, d,
HR-MS (ESI): m/z (M+H+) Calcd for C24H27O3N4: 419.2078. J=7.5Hz), 6.37 (1H, s), 3.76 (2H, t, J=5.4Hz), 3.57 (3H, s),
Found: 419.2072.
3.00 (2H, t, J=5.4Hz), 2.26 (1H, m), 2.20 (3H, s), 2.06 (3H,
Ethyl-5-chloro-1-methyl-1H-pyrazole-4-carboxylate (15) s), 0.74 (2H, m), 0.47 (2H, m). 13C-NMR (126MHz, CDCl3) δ:
t
To a solution of BuONO (2.95mL, 2.46mmol) in acetonitrile 161.14, 154.32, 146.95, 140.07, 139.32, 136.95, 131.10, 125.57,
(ACN) was added CuCl (1.76g, 1.77mmol), and then added 125.45, 123.90, 123.25, 123.17, 116.32, 113.14, 113.02, 105.15,

Vol. 64, No. 4 (2016)
Chem. Pharm. Bull.
333
48.47, 40.72, 34.53, 31.27, 21.13, 15.53, 7.88. HPLC-MS: (2H, m), 3.76 (3H, s), 3.69 (3H, s), 2.91 (2H, m), 2.28 (1H, m),
5.57min, 403.3 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for 0.76 (2H, m), 0.51 (2H, m). 13C-NMR (126MHz, CDCl3) δ:
C24H27O2N4: 403.2129. Found: 403.2122.
160.78, 159.70, 159.01, 156.67, 139.41, 130.20, 129.66, 129.52,
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(5-(3- 125.99, 125.90, 124.10, 116.22, 114.12, 112.94, 109.91, 107.24,
methoxyphenoxy)-1-methyl-1H-pyrazol-4-yl)methanone 101.81, 55.43, 55.31, 50.48, 48.10, 41.44, 31.20, 7.98. HPLC-
(18c) The title compound 18c was obtained from 15 ac- MS: 5.72min, 512.3 (M+H+). HR-MS (ESI): m/z (M+H+)
cording to the general procedure that preparation of title Calcd for C29H30O4N5: 512.2292. Found: 512.2285.
1
compound 18a. mp 58°C. H-NMR (300MHz, CDCl3) δ: 7.53
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(5-(2,5-
(1H, s), 7.14 (2H, m), 7.03 (1H, dt, J=0.9, 6.0Hz), 6.80 (1H, d, dichlorophenoxy)-1-(4-methoxybenzyl)-1H-1,2,3-triazol-4-
J=6.0Hz), 6.61 (1H, m), 6.51 (1H, dt, J=1.2, 5.7, 6.0Hz), 6.32 yl)methanone (23a) The title compound 23a was obtained
(2H, m), 3.76 (2H, t, J=4.2Hz), 3.75 (3H, s), 3.60 (3H, s), 2.97 as a white solid with a similar method that preparation of the
1
(2H, t, J=4.2Hz), 2.31 (1H, m), 0.78 (2H, m), 0.53 (2H, m). title compound 23b from 20. mp 119°C. H-NMR (300MHz,
13C-NMR (126MHz, CDCl3) δ: 160.94, 160.85, 157.45, 146.55, CDCl3) δ: 7.26 (2H, m), 7.11 (3H, m), 7.01 (1H, dt, J=1.2,
140.16, 139.44, 130.20, 125.69, 125.25, 123.24, 116.30, 112.91, 2.0Hz), 6.95 (1H, dd, J=2.1, 6.3Hz), 6.72 (2H, d, J=6.3Hz),
109.08, 106.88, 105.09, 101.70, 55.41, 48.35, 40.64, 34.62, 6.54 (1H, m), 6.36 (1H, m), 5.31 (2H, s), 4.06 (2H, m), 3.75
31.21, 7.96. IR (KBr) cm−1: 2925.24, 1637.36, 1607.05, 1501.83, (3H, s), 3.28 (2H, m), 2.34 (1H, m), 0.77 (2H, m), 0.54 (2H,
1489.73, 1430.37, 1130.12, 743.44. HPLC-MS: 4.90min, 405.3 m). 13C-NMR (126MHz, CDCl3) δ: 159.84, 158.52, 151.23,
(M+H+). HR-MS (ESI): m/z (M+H+) Calcd for C23H25O3N4: 139.65, 133.15, 131.12, 130.27, 129.72, 126.15, 125.20, 124.98,
405.1921. Found: 405.1913.
124.30, 123.64, 121.14, 116.47, 114.20, 113.31, 55.29, 51.14,
Ethyl-5-hydroxy-1-(4-methoxybenzyl)-1H-1,2,3-triazole- 48.86, 31.34, 7.97. IR (KBr) cm−1: 1642.80, 1515.46, 1497.38,
4-carboxylate (19) Compound 19 was prepared as the lit- 1473.21, 1254.21. HPLC-MS: 6.37min, 550.2 (M+H+). HR-MS
erature described.26) 1H-NMR (300MHz, DMSO) δ: 7.20 (2H, (ESI): m/z (M+H+) Calcd for C28H26O3N5Cl2: 550.1407.
d, J=6.3Hz), 6.91 (2H, d, J=6.3Hz), 5.27 (2H, s), 4.24 (2H, q, Found: 550.1403. HR-MS (ESI): m/z (M+H+) Calcd for
J=5.4Hz), 3.72 (1H, s), 1.27 (3H, t, J=5.4 Hz).
Ethyl-5-chloro-1-(4-methoxybenzyl)-1H-1,2,3-triazole-
C28H26O3N5Cl2: 550.1407. Found: 550.1403.
(5-(2,5-Dichlorophenoxy)-1-(4-methoxybenzyl)-1H-1,2,3-
4-carboxylate (20) Compound 20 was synthesized from 19 triazol-4-yl)(4-methyl-3,4-dihydro-quinoxalin-1(2H)-yl)-
with the method described in literature.27) 1H-NMR (300MHz, methanone (24a) In addition to replaced1-cyclopropyl-
CDCl3) δ: 7.26 (2H, d, J=8.7Hz), 6.87 (2H, d, J=8.7Hz), 1,2,3,4-tetrahydroquinoxaline with 1-methyl-1,2,3,4-tetrahy-
5.50 (2H, s), 4.42 (2H, q, J=4.2Hz), 3.79 (1H, s), 1.40 (3H, t, droquinoxaline, the title compound 24a was obtained as a
J=4.2 Hz).
Ethyl-1-(4-methoxybenzyl)-5-(3-methoxyphenoxy)- title compound 23b from 20. mp 116°C. H-NMR (300MHz,
1H-1,2,3-triazole-4-carboxylate (21b) 3-Methoxyphenol CDCl3) δ: 7.26 (2H, m), 7.12 (2H, m), 7.02–6.94 (2H, m), 6.73
white solid with a similar method that preparation of the
1
(334 µL, 3.04mmol) was dissolved in dry DMF, then cooled (2H, d, J=8.4Hz), 6.58 (1H, d, J=8.1Hz), 6.45 (1H, m), 6.37
to 0°C and added NaH (60%, 90mg, 2.25mmol). The reaction (1H, m), 5.30 (2H, s), 4.05 (2H, m), 3.75 (3H, s), 3.19 (2H, m),
mixture was warmed to r.t. and stirred for 0.5h. The residue 2.83 (3H, s). 13C-NMR (126MHz, CDCl3) δ: 159.83, 158.52,
was treated with 20 (600mg, 2.03mmol) and held at 85°C. 151.17, 139.43, 133.16, 131.07, 130.09, 129.73, 126.62, 125.24,
After completion as monitored by TLC, the reaction was 124.96, 123.90, 121.17, 116.23, 115.72, 114.20, 111.52, 55.29,
cooled to r.t. and slowly quenched with water. The resulting 51.14, 50.83, 37.93. IR (KBr) cm−1: 1644.47, 1514.06, 1474.96,
mixture was extracted twice with EtOAc, dried over MgSO4 1248.25, 748.35. HPLC-MS: 5.88min, 524.2 (M+H+). HR-MS
and concentrated. The crude was purified by flash column (ESI): m/z (M+H+) Calcd for C26H24O3N5: 524.1251. Found:
1
chromatography to give 21b (576mg) in 74% yield. H-NMR 524.1251.
(300MHz, CDCl3) δ: 7.20 (2H, d, J=8.7Hz), 7.14 (1H, t,
(1-(4-Methoxybenzyl)-5-(3-methoxyphenoxy)-1H-1,2,3-
J=8.7Hz), 6.78 (2H, d, J=8.7Hz), 6.64 (1H, dd, J=2.1, 8.7Hz), triazol-4-yl)(4-methyl-3,4-dihydro-quinoxalin-1(2H)-yl)-
6.32 (2H, m), 5.33 (2H, s), 4.19 (2H, q, J=4.2Hz), 3.75 (3H, s), methanone (24b) In addition to replaced 1-cyclopropyl-
3.71 (3H, s), 1.12 (3H, t, J=4.2 Hz).
1,2,3,4-tetrahydroquinoxaline with 1-methyl-1,2,3,4-tetrahy-
1-(4-Methoxybenzyl)-5-(3-methoxyphenoxy)-1H-1,2,3- droquinoxaline, the title compound 24b was obtained as a
triazole-4-carboxylic Acid (22b) Compound 22b (502mg) white solid with a similar method that preparation of the
1
was prepared from 21b (570mg, 1.49mmol) according to the title compound 23b from 20. mp 122°C. H-NMR (300MHz,
procedure described that preparation of 17a from 16a in excel- CDCl3) δ: 7.12–7.07 (4H, m), 7.00 (1H, dt, J=1.2, 6.0Hz), 6.76
1
lent yield (95%). H-NMR (300MHz, DMSO) δ: 12.99 (1H, (2H, d, J=6.3Hz), 6.62 (1H, dd, J=1.2, 6.3Hz), 6.57 (1H,
br), 7.19 (1H, t, J=8.4Hz), 7.14 (2H, t, J=8.7Hz), 6.83 (2H, d, J=6.3Hz), 6.33 (1H, m), 6.19 (2H, m), 5.23 (2H, s), 3.88
d, J=8.7Hz), 6.69 (1H, ddd, J=0.6, 2.4, 8.7Hz), 6.42 (1H, t, (2H, m), 3.76 (3H, s), 3.70 (3H, s), 2.77 (5H, m). 13C-NMR
J=2.4Hz), 6.36 (1H, ddd, J=0.6, 2.4, 8.7Hz) 5.35 (2H, s), 3.69 (126MHz, CDCl3) δ: 160.79, 159.69, 158.95, 156.61, 139.22,
(3H, s), 3.68 (3H, s).
130.10, 129.64, 129.13, 126.42, 126.08, 123.60, 115.33, 114.12,
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(1-(4- 110.86, 110.01, 107.17, 101.71, 55.44, 55.31, 50.43, 37.77. HPLC-
methoxybenzyl)-5-(3-methoxyphenoxy)-1H-1,2,3-triazol-4- MS: 5.21min, 486.3 (M+H+). HR-MS (ESI): m/z (M+H+)
yl)methanone (23b) The title compound 23b was obtained Calcd for C27H28O4N5: 486.2136. Found: 486.2123.
as a white solid from 22b following a similar procedure that
(5-(3-Methoxyphenoxy)-1H-1,2,3-triazol-4-yl)(4-meth-
1
preparation of 13c from 12c. mp 111°C. H-NMR (300MHz, yl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (25b) 24b
CDCl3) δ: 7.26–6.97 (6H, m), 6.76 (2H, d, J=7.8Hz), 6.61 (1H, (70mg, 144µmol) was dissolved in trifluoroacetic acid (TFA)
d, J=7.8Hz), 6.40 (1H, m), 6.19 (2H, m), 5.23 (2H, s), 3.88 (5mL), then heated to 65°C and stirred for 2h. Upon comple-

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tion of reaction, the reaction mixture was cooled to r.t. and quenched with 2N aqueous HCl and diluted with water. The
concentrated. The residue was then re-dissolved in DCM and mixture was extracted with DCM (3×) and the organic phases
washed with water. Then the solvent was removed under re- were combined. The combined organic layer was washed
duced pressure, and the crude reaction mixture was purified twice with brine, dried over MgSO4 and concentrated. The
by preparative TLC to yield the title compound 25b (35mg, residue was purified by flash column chromatography to give
1
1
66%) as a light yellow solid. mp 157°C. H-NMR (300MHz, the product 29a (249mg, 75%). H-NMR (300MHz, CDCl3) δ:
CDCl3) δ: 7.18 (1H, d, J=8.4Hz), 7.02 (1H, d, J=7.8Hz), 6.61 7.36 (1H, d, J=6.9Hz), 7.11 (1H, dd, J=1.8, 6.9Hz), 7.10 (1H,
(3H, m), 6.36 (3H, m), 3.99 (2H, m), 3.73 (3H, s), 3.21 (2H, d, J=1.8Hz), 4.31 (2H, q, J=5.4Hz), 2.61 (3H, s), 1.32 (3H, t,
m), 2.87 (3H, s). HPLC-MS: 3.98min, 366.2 (M+H+). HR-MS J=5.4 Hz).
(ESI): m/z (M+H+) Calcd for C19H20O3N5: 366.1561. Found:
366.1556.
Ethyl-4-(2-bromo-5-chlorophenoxy)-2-methylthiazole-
5-carboxylate (29c) In addition to use CuBr2 instead of
(5-(2,5-Dichlorophenoxy)-1H-1,2,3-triazol-4-yl)(4-meth- CuCl2, 29c was synthesized from 28a as following a similar
1
yl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (25a) The procedure that preparation 29a from 28a. H-NMR (300MHz,
title compound 25a was prepared as a light yellow solid from CDCl3) δ: 7.52 (1H, d, J=6.0Hz), 7.04 (2H, m), 4.31 (2H, q,
24a according to the similar procedure that preparation of the J=5.4Hz), 2.62 (3H, s), 1.31 (3H, t, J=5.4 Hz).
1
title compound 25b from 24b. mp 149°C. H-NMR (300MHz,
Ethyl-4-(3-chlorophenoxy)-2-methylthiazole-5-carbox-
CDCl3) δ: 7.23 (1H, m), 6.97 (1H, m), 6.88 (1H, m), 6.55–6.39 ylate (29e) A solution of 28a (312mg, 1.0mmol) in ACN,
t
(4H, m), 4.07 (2H, d, J=5.4Hz), 3.48 (2H, d, J=5.4Hz), was treated with BuONO and held at reflux for 8h. After the
2.87 (3H, s). 13C-NMR (126MHz, CDCl3) δ: 150.77, 139.67, reaction was completed, the reaction mixture was cooled to r.t.
132.79, 130.65, 127.13, 124.97, 123.73, 123.02, 122.27, 118.83, and quenched with 2N aqueous HCl, then diluted with water.
115.33, 111.24, 50.73, 40.13, 37.90. IR (KBr) cm−1: 1629.60, The crude mixture was extracted with EtOAc, and the com-
1512.67, 1474.02, 1401.87, 1329.41, 1229.21, 733.17. HPLC-MS: bined organic layer was washed twice with brine, dried over
4.99min, 404.1 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd MgSO4, filtered and concentrated under reduced pressure.
for C18H16O2N5Cl2: 404.0676. Found: 404.0664.
Ethyl-4-hydroxy-2-methylthiazole-5-carboxylate
The residue was purified by flash column chromatography to
(26) yield 29e (194mg) in 65%. H-NMR (300MHz, CDCl3) δ: 7.27
1
Compound 26 was synthesized with the method described in (1H, t, J=6.0Hz), 7.12 (1H, dd, J=1.5, 6.0Hz), 7.09 (1H, d,
the patent.28) 1H-NMR (300MHz, CDCl3) δ: 9.88 (1H, br), 4.34 J=1.5Hz), 7.00 (1H, dd, J=1.5, 6.0Hz), 4.29 (2H, q, J=5.4Hz),
(2H, q, J=7.2Hz), 2.65 (1H, s), 1.35 (3H, t, J=7.2 Hz).
Ethyl-4-(5-chloro-2-nitrophenoxy)-2-methylthiazole-
2.63 (3H, s), 1.30 (3H, t, J=5.1 Hz).
4-(2,5-Dichlorophenoxy)-2-methylthiazole-5-carboxylic
5-carboxylate (27a) To a solution of 26 in ethanol was Acid The intermediate was prepared with the same meth-
added dropwise with fresh sodium ethoxide and then allowed od described that preparation of 17a from 16a. 1H-NMR
to stir at 45°C for 0.5h. The reaction mixture was cooled to (300MHz, DMSO) δ: 13.21 (1H, br), 7.60 (1H, d, J=6.6Hz),
r.t. and filtered to give sodium salt of 26 (2g, 9.57mmol). 7.38 (1H, d, J=1.5Hz), 7.31 (1H, d, J=1.5, 6.6Hz), 2.55 (3H, s).
The residue was treated with 4-chloro-2-fluoro-1-nitrobenzene
4-(2-Bromo-5-chlorophenoxy)-2-methylthiazole-5-car-
(1.7g, 9.71mmol) in NMP and heated by microwave at 125°C boxylic Acid The intermediate was prepared with the same
1
for 2h. Then the reaction mixture was cooled to r.t., poured method described that preparation of 17a from 16a. H-NMR
into water, extracted with EtOAc three times and combined (300MHz, DMSO) δ: 13.19 (1H, br), 7.60 (1H, d, J=6.6Hz),
the organic phases. The organic layer was washed with brine 7.38 (1H, d, J=1.5Hz), 7.31 (1H, d, J=1.5, 6.6Hz), 2.55 (3H, s).
twice, dried over MgSO4, filtered and concentrated. The
4-(3-Chlorophenoxy)-2-methylthiazole-5-carboxylic Acid
crude was purified by flash column chromatography to give The intermediate was prepared with the same method de-
1
1
compound 27a (2.21g) in yield of 65%. H-NMR (300MHz, scribed that preparation of 17a from 16a. H-NMR (300MHz,
CDCl3) δ: 8.02 (1H, d, J=8.7Hz), 7.29 (1H, dd, J=2.1, 8.7Hz), DMSO) δ: 13.18 (1H, br), 7.39 (1H, t, J=6.0Hz), 7.22 (1H, dd,
7.27 (2H, d, J=2.1Hz), 4.31 (2H, q, J=7.2Hz), 2.57 (3H, s), J=1.5, 6.0Hz), 7.17 (1H, d, J=1.5Hz), 7.03 (1H, dd, J=1.5,
1.32 (3H, t, J=7.2 Hz).
Ethyl-4-(2-amino-5-chlorophenoxy)-2-methylthiazole-
6.0Hz), 2.58 (3H, s).
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-
5-carboxylate (28a) To a solution of 27a (1.37g, 4.0mmol) (2,5-dichlorophenoxy)-2-methylthiazol-5-yl)methanone
in THF–H2O (2:1) was added iron powder (2.24g, 40mmol) (30c) The title compound 30c was prepared as a light yel-
and NH4Cl (2.14g, 40mmol), and then stirred at 65°C over- low solid according to the general procedure that preparation
night. After completion of the reaction as monitored by TLC, of 13c from 12c. mp 160°C. 1H-NMR (400MHz, CDCl3)
the mixture was cooled to r.t., filtered by siliceousearth and δ: 7.21 (1H, d, J=8.6Hz), 6.95–6.89 (2H, m), 6.85 (1H, dd,
the filter cake was washed with DCM. The filtrate was ex- J=8.3, 1.5Hz), 6.79 (1H, d, J=7.9Hz), 6.52 (1H, ddd, J=8.4,
tracted with DCM and the organic layer was combined. The 7.2, 1.5Hz), 6.13 (1H, s), 3.94 (2H, t, J=5.5Hz), 3.49 (2H, t,
residue was evaporated under reduced pressure to give crude J=5.5Hz), 2.61 (3H, s), 2.30 (1H, tt, J=6.8, 3.7Hz), 0.74–0.68
product 28a and was used directly in the next step without (2H, m), 0.45–0.39 (2H, m). 13C-NMR (101MHz, CDCl3) δ:
further purification. HPLC-MS: 313.13 (M+H+).
166.75, 159.52, 154.26, 151.09, 139.83, 132.58, 130.40, 126.51,
Ethyl-4-(2,5-dichlorophenoxy)-2-methylthiazole-5- 125.52, 124.65, 122.95, 122.47, 119.93, 116.00, 113.22, 112.84,
carboxylate (29a) To a solution of 28a (312mg, 1.0mmol) 48.98, 41.30, 31.22, 20.24, 8.04. IR (KBr) cm−1: 1646.23,
in ACN was added CuCl2 (202mg, 1.5mmol), and slowly 1536.75, 1506.15, 1472.16, 1405.36, 1331.26, 748.47. HPLC-
t
added BuONO (238µL, 2.0mmol). The reaction mixture was MS: 6.49min, 460.1 (M+H+). HR-MS (ESI): m/z (M+H+)
allowed to stir at r.t. for 24h, then heated to 60°C and stir- Calcd for C22H19Cl2N3O2S: 460.0648. Found: 460.0661.
ring was continued for 2h. Upon completing, the reaction was
(4-(2,5-Dichlorophenoxy)-2-methylthiazol-5-yl)(4-

Vol. 64, No. 4 (2016)
Chem. Pharm. Bull.
335
methyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone
(30d) 504.0143. Found: 504.0130.
In addition to replaced 1-cyclopropyl-1,2,3,4-tetrahydro-
(4-(2-Bromo-5-chlorophenoxy)-2-methylthiazol-5-yl)(4-
quinoxaline with 1-methyl-1,2,3,4-tetrahydro-quinoxaline, 30d methyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone
(30f)
was prepared as a light yellow solid according to the gen- In addition to replaced 1-cyclopropyl-1,2,3,4-tetrahydro-
eral procedure that preparation of 13c from 12c. mp 126°C. quinoxaline with 1-methyl-1,2,3,4-tetrahydro-quinoxaline, the
1H-NMR (300MHz, CDCl3) δ: 7.19 (1H, d, J=8.7Hz), title compound 30e was obtained as a light yellow solid ac-
6.90 (1H, dd, J=2.4, 8.4Hz), 6.84 (1H, dt, J=1.2, 7.8Hz), cording to the general procedure that preparation of 13c from
1
6.74 (1H, d, J=7.2Hz), 6.44 (1H, dt, J=1.2, 7.2, 7.8Hz), 12c. mp 134°C. H-NMR (300MHz, CDCl3) δ: 7.35 (1H, d,
6.24 (1H, d, J=7.8Hz), 6.17 (1H, s), 3.99 (2H, t, J=5.4Hz), J=8.4Hz), 6.86–6.82 (2H, m), 6.73 (1H, d, J=8.1Hz), 6.44
3.49 (2H, t, J=5.4Hz), 2.78 (3H, s), 2.63 (3H, s). 13C-NMR (1H, d, J=7.8Hz), 6.21 (1H, d, J=8.4Hz), 6.10 (1H, s), 3.99
(126MHz, CDCl3) δ: 166.64, 159.32, 153.62, 150.84, 139.48, (2H, t, J=5.4Hz), 3.51 (2H, t, J=5.4Hz), 2.78 (3H, s), 2.63
132.43, 130.15, 126.81, 124.77, 124.07, 122.92, 121.72, 119.05, (3H, s). 13C-NMR (126MHz, CDCl3) δ: 166.66, 159.30, 153.57,
115.08, 113.50, 111.03, 50.78, 41.03, 37.73, 20.13. IR (KBr) 151.95, 146.03, 139.46, 133.25, 133.09, 126.86, 124.74, 124.46,
cm−1: 1640.10, 1625.80, 1512.29, 1473.01, 1407.68, 1333.55, 122.93, 118.91, 115.02, 113.71, 111.00, 50.80, 40.98, 37.79,
742.15. HPLC-MS: 6.01min, 434.1 (M+H+). HR-MS (ESI): 20.14. HPLC-MS: 6.09min, 478.1 (M+H+). HR-MS (ESI):
m/z (M+H+) Calcd for C20H18O2N3Cl2S: 434.0491. Found: m/z (M+H+) Calcd for C20H18O2N3BrClS: 477.9986. Found:
434.0487.
(4-(2-Chloro-5-methylphenoxy)-2-methylthiazol-5-yl)(4-
477.9980.
(4-(2-Bromo-5-methylphenoxy)-2-methylthiazol-5-yl)(4-
cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone
(30a) The title compound 30a was obtained as a light yellow (30g) The title compound 30g was obtained as a light yellow
solid according to the general procedure that preparation of solid according to the general procedure that preparation of
1
1
13c from 12c. mp 136°C. H-NMR (300MHz, CDCl3) δ: 7.31 13c from 12c. mp 133°C. H-NMR (300MHz, CDCl3) δ: 7.32
(1H, dd, J=1.2, 7.2Hz), 7.03–6.97 (2H, m), 6.92–6.88 (3H, m), (1H, d, J=6.0Hz), 6.88 (3H, m), 6.71 (1H, dd, J=0.9, 6.0Hz),
6.51 (1H, m), 6.33 (1H, m), 3.96 (2H, t, J=5.4Hz), 3.46 (2H, t, 6.53 (1H, m), 5.95 (1H, d, J=0.9Hz), 3.95 (2H, t, J=4.2Hz),
J=5.4Hz), 2.59 (3H, s), 2.32 (1H, m), 0.71 (2H, m), 0.42 (2H, 3.50 (2H, t, J=4.2Hz), 2.59 (3H, s), 2.31 (1H, m), 2.15 (3H,
m). 13C-NMR (126MHz, CDCl3) δ: 166.36, 159.89, 155.34, s), 0.69 (2H, m), 0.41 (2H, m). 13C-NMR (126MHz, CDCl3)
150.44, 139.76, 137.49, 129.41, 125.87, 125.69, 125.46, 122.96, δ: 166.37, 159.86, 155.25, 151.56, 139.74, 138.26, 132.38,
120.98, 120.37, 115.79, 113.15, 111.52, 48.85, 41.70, 31.06, 125.89, 125.66, 122.97, 120.24, 118.57, 115.68, 113.14, 111.76,
20.86, 20.11, 7.87. IR (KBr) cm−1: 1628.74, 1506.62, 1415.80, 109.53, 48.89, 41.56, 31.08, 20.88, 20.13, 7.90. IR (KBr) cm−1:
1332.32, 1067.33, 757.53. HPLC-MS: 6.27min, 440.2 (M+H+). 1628.27, 1526.51, 1505.97, 1480.77, 1413.50, 1331.67, 1308.91,
HR-MS (ESI): m/z (M+H+) Calcd for C23H23O2N3ClS: 756.78. HPLC-MS: 6.33min, 484.2 (M+H+). HR-MS (ESI):
440.1194. Found: 440.1189.
(4-(2-Chloro-5-methylphenoxy)-2-methylthiazol-5-yl)(4- 484.0683.
methyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (30b) (4-(2-Bromo-5-methylphenoxy)-2-methylthiazol-5-yl)(4-
In addition to replaced 1-cyclopropyl-1,2,3,4-tetrahydro-qui- methyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (30h)
m/z (M+H+) Calcd for C23H23O2N3BrS: 484.0689. Found:
noxaline with 1-methyl-1,2,3,4-tetrahydro-quinoxaline, the title In addition to replaced 1-cyclopropyl-1,2,3,4-tetrahydro-
compound 30b was obtained as a light yellow solid according quinoxaline with 1-methyl-1,2,3,4-tetrahydro-quinoxaline, the
to the general procedure that preparation of 13c from 12c. mp title compound 30h was obtained as a light yellow solid
1
137°C. H-NMR (300MHz, CDCl3) δ: 7.15 (1H, d, J=8.1Hz), according to the general procedure that preparation of 13c
6.87–6.82 (2H, m), 6.75 (1H, dd, J=1.2, 8.1Hz), 6.45 (1H, m), from 12c. mp 129°C. 1H-NMR (300MHz, CDCl3) δ: 7.32
6.32 (1H, d, J=7.8Hz), 6.10 (1H, s), 4.00 (2H, t, J=5.4Hz), (1H, d, J=6.0Hz), 6.88 (3H, m), 6.71 (1H, dd, J=0.9, 6.0Hz),
3.46 (2H, t, J=5.4Hz), 2.79 (3H, s), 2.60 (3H, s), 2.17 (3H, s). 6.53 (1H, m), 6.10 (1H, s), 3.99 (2H, t, J=5.4Hz), 3.49 (2H, t,
13C-NMR (126MHz, CDCl3) δ: 166.38, 159.83, 154.93, 150.41, J=5.4Hz), 2.79 (3H, s), 2.60 (3H, s), 2.13 (3H, s). 13C-NMR
139.61, 137.46, 129.36, 126.30, 125.10, 123.09, 120.50, 119.75, (126MHz, CDCl3) δ: 166.52, 159.81, 154.82, 151.51, 139.61,
118.32, 115.11, 112.21, 111.30, 50.84, 41.58, 37.87, 20.93, 138.21, 132.33, 128.75, 126.32, 125.53, 124.93, 122.99, 119.62,
20.12. HPLC-MS: 5.76min, 414.2 (M+H+). HR-MS (ESI): m/z 117.76, 115.02, 111.28, 50.85, 41.16, 37.90, 20.96, 20.13. HPLC-
(M+H+) Calcd for C21H21O2N3ClS: 414.1038. Found: 414.1031.
(4-(2-Bromo-5-chlorophenoxy)-2-methylthiazol-5-yl)(4- Calcd for C21H21O2N3BrS: 458.0532. Found: 458.0531.
cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(2-
(30e) The title compound 30e was obtained as a light yel- methyl-4-(m-tolyloxy)thiazol-5-yl)methanone (30i) The
MS: 6.16min, 458.1 (M+H+). HR-MS (ESI): m/z (M+H+)
low solid according to the general procedure that preparation title compound 30i was obtained ass a light yellow solid ac-
of 13c from 12c. mp 144°C. 1H-NMR (300MHz, CDCl3) cording to the general procedure that preparation of 13c
δ: 7.37 (1H, d, J=7.2Hz), 6.94–6.76 (4H, m), 6.52 (1H, dt, from 12c. mp 116°C. 1H-NMR (300MHz, CDCl3) δ: 7.10
J=1.5, 7.5Hz), 6.04 (1H, s), 3.93 (2H, t, J=5.4Hz), 3.51 (2H, t, (1H, t, J=7.8Hz), 7.01–6.91 (3H, m), 6.81 (1H, d, J=7.8Hz),
J=5.4Hz), 2.61 (3H, s), 2.31 (1H, m), 0.71 (2H, m), 0.42 (2H, 6.55–6.50 (2H, m), 6.47 (1H, s), 3.92 (2H, t, J=5.4Hz), 3.38
m). 13C-NMR (126MHz, CDCl3) δ: 166.64, 159.37, 154.06, (2H, t, J=5.4Hz), 2.60 (3H, s), 2.30 (1H, m), 0.74 (2H, m),
152.08, 139.66, 133.28, 133.19, 126.42, 125.32, 124.90, 122.83, 0.42 (2H, m). 13C-NMR (126MHz, CDCl3) δ: 166.49, 159.61,
119.61, 115.78, 113.06, 112.90, 110.79, 48.89, 41.08, 31.14, 155.78, 154.88, 139.93, 134.37, 129.81, 126.23, 125.85, 123.81,
20.13, 7.94. IR (KBr) cm−1: 1645.76, 1534.69, 1505.39, 1466.46, 122.70, 118.58, 116.32, 116.21, 113.21, 112.50, 48.95, 41.51,
1403.98, 1331.27, 747.58. HPLC-MS: 6.55min, 504.1 (M+H+). 31.15, 20.09, 7.92. IR (KBr) cm−1: 1622.93, 1591.20, 1506.27,
HR-MS (ESI): m/z (M+H+) Calcd for C22H20O2N3BrClS: 1406.76, 1332.96, 1214.85, 1086.47, 746.28. HPLC-MS:

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Chem. Pharm. Bull.
Vol. 64, No. 4 (2016)
6.18min, 426.2 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for light yellow solid in a manner similar to the title compound
1
C22H21O2N3ClS: 426.1038. Found: 426.1033.
30e. mp 128°C. H-NMR (300MHz, CDCl3) δ: 7.31 (1H, dd,
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(2- J=1.2, 7.2Hz), 7.03–6.97 (2H, m), 6.92–6.88 (3H, m), 6.51
methyl-4-(m-tolyloxy)thiazol-5-yl)methanone (30j) The title (1H, m), 6.33 (1H, m), 3.96 (2H, t, J=5.4Hz), 3.46 (2H, t,
compound 30j was obtained as a light yellow solid according J=5.4Hz), 2.59 (3H, s), 2.32 (1H, m), 0.71 (2H, m), 0.42 (2H,
to the general procedure that preparation of 13c from 12c. m). 13C-NMR (126MHz, CDCl3) δ: 166.74, 159.21, 153.82,
mp 110°C. 1H-NMR (300MHz, CDCl3) δ: 7.09–6.94 (3H, 150.10, 139.74, 133.34, 132.81, 126.43, 125.40, 123.27, 122.79,
m), 6.88 (1H, d, J=7.8Hz), 6.83 (1H, d, J=7.5Hz), 6.57-6.51 120.98, 116.54, 115.86, 113.13, 112.73, 48.85, 41.15, 31.12,
(1H, m), 6.42 (1H, m), 6.34 (1H, s), 3.92 (2H, t, J=5.7Hz), 20.10, 7.97. HPLC-MS: 7.14min, 538.1 (M+H+). HR-MS
3.36 (2H, t, J=5.7Hz), 2.58 (3H, s), 2.30 (1H, m), 2.24 (3H, (ESI): m/z (M+H+) Calcd for C22H19O2N3BrCl2S: 537.9753.
s), 0.71 (2H, m), 0.41 (2H, m). 13C-NMR (126MHz, CDCl3) δ: Found: 537.9753.
166.28, 160.07, 155.99, 155.41, 139.87, 139.19, 128.82, 125.98,
(4-(5-Chloro-2-methylphenoxy)-2-methylthiazol-5-yl)(4-
125.91, 124.49, 122.83, 118.68, 116.25, 115.13, 113.19, 111.65, cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone
48.86, 41.83, 31.08, 21.28, 20.10, 7.89. IR (KBr) cm−1: 1623.00, (31a) To a solution of 30e (102mg, 0.2mmol) in dry
1506.34, 1405.22, 1334.80, 1306.90, 1248.01, 1146.39, 746.32. 1,4-dioxane, was added Zn(CH3)2 (333 µL, 0.4mmol) and
HPLC-MS: 5.98min, 406.2 (M+H+). HR-MS (ESI): m/z PdCl2(dppf)·CH2Cl2 (16.3mg, 0.02mmol). The reaction mix-
(M+H+) Calcd for C23H24O2N3S: 406.1584. Found: 406.1578.
ture was stirred at reflux under an atmosphere of nitrogen
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-(2,4- for 2h. After completion, the reaction was quenched with
dichlorophenoxy)-2-methylthiazol-5-yl)methanone (30k) CH3OH and stirring was continued for 10min. The precipitate
The title compound 30k was synthesized as a light yellow was removed by filtration and the filtrate was concentrated
solid in a manner similar to the title compound 30c. mp under reduced pressure. The residue was purified to give the
1
87°C. H-NMR (400MHz, CDCl3) δ: 7.31 (1H, d, J=2.5Hz), title compound 31a (71mg) as a light yellow solid in yield of
1
6.98 (1H, dd, J=8.8, 2.6Hz), 6.95–6.88 (2H, m), 6.85 (1H, 81%. mp 98°C. H-NMR (300MHz, CDCl3) δ: 7.01–6.89 (4H,
d, J=8.0Hz), 6.50 (1H, ddd, J=8.2, 6.5, 2.2Hz), 6.22 (1H, m), 6.83 (1H, d, J=5.7Hz), 6.56 (1H, dt, J=1.2, 5.7Hz), 6.05
d, J=8.8Hz), 3.95 (2H, t, J=5.5Hz), 3.47 (2H, t, J=5.5Hz), (1H, s), 3.93 (2H, t, J=4.2Hz), 3.42 (2H, t, J=4.2Hz), 2.59
2.57 (3H, s), 2.33 (1H, tt, J=6.8, 3.7Hz), 0.77–0.70 (2H, m), (3H, s), 2.27 (1H, m), 2.04 (3H, s), 0.70 (2H, m), 0.35 (2H, m).
0.46–0.39 (2H, m). 13C-NMR (126MHz, CDCl3) δ: 166.48, 13C-NMR (126MHz, CDCl3) δ: 166.49, 159.81, 155.52, 153.78,
159.60, 154.91, 149.57, 139.83, 129.58, 129.30, 127.36, 126.12, 139.81, 131.31, 131.17, 126.43, 126.37, 125.83, 123.80, 122.81,
125.72, 125.23, 122.77, 121.00, 115.99, 113.18, 111.48, 48.86, 118.27, 116.26, 113.26, 111.54, 49.06, 41.37, 31.08, 20.11, 15.76,
41.56, 31.10, 20.05, 7.97. HPLC-MS: 6.62min, 460.1 (M+H+). 7.83. HPLC-MS: 6.43min, 440.2 (M+H+). HR-MS (ESI): m/z
HR-MS (ESI): m/z (M+H+) Calcd for C22H20O2N3Cl2S: (M+H+) Calcd for C23H23O2N3ClS: 440.1194. Found: 440.1190.
460.0648. Found: 460.0641.
(4-(4-Chlorophenoxy)-2-methylthiazol-5-yl)(4-cyclo- dimethylphenoxy)-2-methylthiazol-5-yl)methanone
propyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (30l) The title compound 31b was prepared as a light yellow solid
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-(2,5-
(31b)
The title compound 30l was synthesized as a light yellow from 30g according to the similar procedure that prepara-
1
solid in a manner similar to the title compound 30i. mp 88°C. tion of 31a from 30e. mp 90°C. H-NMR (300MHz, CDCl3)
1H-NMR (400MHz, CDCl3) δ: 7.16–7.11 (2H, m), 7.03–6.94 δ: 6.98–6.96 (3H, m), 6.92 (1H, d, J=6.0Hz), 6.75 (1H, d,
(2H, m), 6.83 (1H, d, J=7.9Hz), 6.52 (3H, ddd, J=12.6, J=6.0Hz), 6.56 (1H, m), 5.99 (1H, s), 3.94 (2H, t, J=4.2Hz),
7.8, 1.8Hz), 3.93 (2H, t, J=5.6Hz), 3.38 (2H, t, J=5.6Hz), 3.39 (2H, t, J=4.2Hz), 2.57 (3H, s), 2.29 (1H, m), 2.17 (3H, s),
2.58 (3H, s), 2.31 (1H, tt, J=6.7, 3.7Hz), 0.77–0.71 (2H, m), 2.01 (3H, s), 0.69 (2H, m), 0.37 (2H, m). 13C-NMR (126MHz,
0.44–0.38 (2H, m). 13C-NMR (126MHz, CDCl3) δ: 166.43, CDCl3) δ: 166.28, 160.28, 156.60, 153.52, 139.80, 136.27,
159.76, 155.50, 153.83, 140.00, 129.09, 128.85, 126.09, 122.71, 130.36, 126.03, 125.87, 124.88, 124.65, 122.86, 118.70, 116.18,
119.71, 116.35, 113.26, 111.62, 48.94, 41.62, 31.14, 20.07, 7.96. 113.27, 110.54, 48.94, 41.77, 31.08, 20.87, 20.13, 15.76, 7.83.
HPLC-MS: 6.18min, 426.2 (M+H+). HR-MS (ESI): m/z HPLC-MS: 6.29min, 420.3 (M+H+). HR-MS (ESI): m/z
(M+H+) Calcd for C22H21O2N3ClS: 426.1038. Found: 426.1035. (M+H+) Calcd for C24H26O2N3S: 420.1740. Found: 420.1732.
(4-(2-Chlorophenoxy)-2-methylthiazol-5-yl)(4-cyclo-
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-(2,5-
propyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (30m) dichloro-4-methylphenoxy)-2-methylthiazol-5-yl)metha-
The title compound 30m was synthesized as a yellow solid none (31c) The title compound 31c was prepared from 30n
in a manner similar to the title compound 30c. mp 93°C. according to the similar procedure that preparation of 31a
1H-NMR (300MHz, CDCl3) δ: 7.31 (1H, dd, J=1.2, 7.2Hz), from 30e. mp 167°C. 1H-NMR (400MHz, CDCl3) δ: 7.16
7.03–6.97 (2H, m), 6.92–6.88 (3H, m), 6.51 (1H, m), 6.33 (1H, (1H, s), 6.97–6.87 (2H, m), 6.84 (1H, d, J=7.9Hz), 6.58–6.49
m), 3.96 (2H, t, J=5.4Hz), 3.46 (2H, t, J=5.4Hz), 2.59 (3H, s), (1H, m), 6.18 (1H, s), 3.95 (2H, t, J=5.5Hz), 3.48 (2H, t,
2.32 (1H, m), 0.71 (2H, m), 0.42 (2H, m). 13C-NMR (126MHz, J=5.5Hz), 2.58 (3H, s), 2.32 (1H, tt, J=7.1, 3.7Hz), 2.26 (3H,
CDCl3) δ: 166.37, 159.85, 155.32, 150.87, 139.77, 129.98, s), 0.75–0.67 (2H, m), 0.45–0.37 (2H, m). 13C-NMR (126MHz,
127.28, 126.01, 125.68, 124.73, 124.34, 122.86, 120.07, 116.00, CDCl3) δ: 166.52, 159.63, 154.87, 148.87, 139.77, 132.62,
113.15, 111.39, 48.83, 41.79, 31.08, 20.07, 7.90. HPLC-MS: 132.29, 131.04, 126.27, 125.62, 122.84, 122.30, 120.58, 115.94,
5.94min, 426.2 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for 113.13, 111.57, 48.86, 41.48, 31.07, 20.10, 19.28, 7.92. IR (KBr)
C22H21O2N3ClS: 426.1038. Found: 426.1029.
cm−1: 1630.98, 1414.40, 1328.77, 1085.80, 741.82. HPLC-MS:
(4-(4-Bromo-2,5-dichlorophenoxy)-2-methylthiazol-5- 6.89min, 474.2 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for
yl)(4-cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)metha- C23H22O2N3Cl2S: 474.0804. Found: 474.0800.
none (30n) The title compound 30n was synthesized as a
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-(2,5-

Vol. 64, No. 4 (2016)
Chem. Pharm. Bull.
337
dichloro-4-hydroxyphenoxy)-2-methylthiazol-5-yl)metha- 139.78, 138.10, 127.08, 125.92, 125.21, 124.82, 123.10, 121.75,
none (31d) A flask was charged with 30n (85mg, 0.16mmol), 115.86, 113.07, 48.84, 41.70, 31.13, 21.45, 20.03, 7.91. HPLC-
PdCl2(dppf)·CH2Cl2 (26mg, 0.032mmol), bis(pinacolato)- MS: 5.72min, 451.2 (M+H+). HR-MS (ESI): m/z (M+H+)
diboron (60mg, 0.24mmol) and KAc (31mg, 0.31mmol) in Calcd for C23H23O4N4S: 451.1435. Found: 451.1430.
1,4-dioxane under an atmosphere of nitrogen, and then heat
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-
at 130°C for 3h. After completion, the resulting mixture was (2,5-dichlorophenoxy)-2-ethylthiazol-5-yl)methanone (37a)
cooled to r.t. and filtered to remove the suspended solids. The The title compound 37a was obtained as a light yellow solid
filtrate was concentrated to dryness to give a crude intermedi- according to the procedure that preparation of the title com-
1
ate and that was carried forward crude into the next step. The pound 30c. mp 102°C. H-NMR (400MHz, CDCl3) δ: 7.20
crude intermediate was redissolved in THF, then cooled to (1H, d, J=8.5Hz), 6.95–6.87 (2H, m), 6.87–6.82 (1H, m),
0°C and H2O2 (357 µL, 3.15mmol) was added dropwise. After 6.79 (1H, d, J=7.8Hz), 6.52 (1H, td, J=8.1, 7.6, 1.5Hz), 6.14
the addition was completed, the reaction mixture was warmed (1H, s), 3.94 (2H, t, J=5.5Hz), 3.49 (2H, t, J=5.4Hz), 2.91
to r.t. and stirring was continued for 3h. Upon completion, (2H, q, J=7.5Hz), 2.34–2.27 (1H, m), 1.33 (3H, t, J=7.6Hz),
the reaction was quenched with saturated aqueous Na2SO3 0.75–0.69 (2H, m), 0.46–0.40 (2H, m). 13C-NMR (126MHz,
and extracted with EtOAc three times. The combined organic CDCl3) δ: 173.34, 159.55, 153.98, 150.97, 139.63, 132.40,
phases were washed with brine, dried over MgSO4, filtered 130.24, 126.32, 125.33, 124.37, 122.78, 122.23, 119.64, 115.85,
and evaporated under reduced pressure. The residue was puri- 113.06, 112.40, 48.82, 41.26, 31.12, 27.58, 13.45, 7.91. IR (KBr)
fied by flash column chromatography to obtain the title com- cm−1: 1632.63, 1475.48, 1414.25, 1329.43, 734.26. HPLC-MS:
pound 31b (45mg) as a light yellow solid in 60% yield. mp 7.33min, 474.1 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for
1
187°C. H-NMR (400MHz, CDCl3) δ: 7.00–6.89 (3H, m), 6.84 C23H22O2N3Cl2S: 474.0804. Found: 474.0797.
(1H, d, J=7.9Hz), 6.54 (1H, d dd, J=8.4, 6.8, 1.9Hz), 6.11 (1H,
(4-(3-Chlorophenoxy)-2-ethylthiazol-5-yl)(4-cyclopro-
s), 5.93 (1H, s), 3.95 (2H, t, J=5.5Hz), 3.48 (2H, t, J=5.5Hz), pyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (37b) The
2.59 (3H, s), 2.32 (1H, tt, J=6.8, 3.7Hz), 0.76–0.67 (2H, m), title compound 37b was obtained as a light yellow solid
0.44–0.37 (2H, m). 13C-NMR (126MHz, CDCl3) δ: 167.01, according to the procedure that preparation of the title com-
159.65, 155.37, 148.68, 143.87, 139.98, 126.35, 125.80, 123.94, pound 30i. mp 84°C. 1H-NMR (400MHz, CDCl3) δ: 7.10
122.81, 120.94, 118.61, 117.07, 115.93, 113.25, 110.64, 48.89, (1H, t, J=8.1Hz), 7.02–6.93 (3H, m), 6.81 (1H, d, J=8.0Hz),
41.57, 31.01, 19.90, 7.95. HPLC-MS: 5.28min, 476.1 (M+H+). 6.55–6.47 (3H, m), 3.92 (2H, t, J=5.6Hz), 3.37 (2H, t,
HR-MS (ESI): m/z (M+H+) Calcd for C22H20O3N3Cl2S: J=5.6Hz), 2.91 (2H, q, J=7.5Hz), 2.35–2.28 (1H, m), 1.33 (3H,
476.0597. Found: 476.0601.
t, J=7.6Hz), 0.78–0.72 (2H, m), 0.47–0.41 (2H, m). 13C-NMR
4-(5-Chloro-2-nitrophenoxy)-2-methylthiazole-5-car- (126MHz, CDCl3) δ: 173.23, 159.77, 155.85, 154.73, 139.87,
boxylic Acid The carboxylic acid intermediate shown 134.35, 129.78, 126.18, 125.81, 123.69, 122.67, 118.47, 116.33,
above was synthesized from 27a with the method described 116.06, 113.20, 112.24, 48.94, 41.55, 31.19, 29.70, 27.58, 13.47,
1
that preparation of 17a from 16a in yield of 93%. H-NMR 7.94. HPLC-MS: 7.02min, 440.2 (M+H+). HR-MS (ESI): m/z
(300MHz, DMSO) δ: 10.28 (1H, br), 7.91 (1H, d, J=7.2Hz), (M+H+) Calcd for C23H23O2N3ClS: 440.1194. Found: 440.1188.
7.15 (1H, d, J=1.2Hz), 7.02 (1H, dd, J=1.2, 7.2Hz), 2.54 (3H,
s).
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-(2,5-
dichlorophenoxy)-2-isopropylthiazol-5-yl)methanone (37c)
(4-(5-Chloro-2-nitrophenoxy)-2-methylthiazol-5-yl)(4- The title compound 37c was obtained as a light yellow solid
cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone according to the procedure that preparation of the title com-
1
(32a) The title compound 32a was obtained as a yellow solid pound 30c. mp 89°C. H-NMR (400MHz, CDCl3) δ: 7.20 (1H,
from the intermediates shown above according to the gen- d, J=8.5Hz), 6.92 (1H, dd, J=8.5, 2.3Hz), 6.90–6.82 (2H, m),
eral procedure that preparation of 13c from 12c. mp 159°C. 6.79 (1H, d, J=7.8Hz), 6.51 (1H, ddd, J=8.1, 7.0, 1.8Hz), 6.17
1H-NMR (300MHz, CDCl3) δ: 7.83 (1H, d, J=8.7Hz), 7.10 (1H, s), 3.95 (2H, t, J=5.4Hz), 3.49 (2H, t, J=5.5Hz), 3.17
(1H, dd, J=2.1, 8.7Hz), 6.93–6.81 (3H, m), 6.55–6.50 (1H, m), (1H, p, J=6.9Hz), 2.34–2.27 (1H, m), 1.33 (6H, d, J=6.9Hz),
6.29 (1H, s), 3.93 (2H, t, J=5.4Hz), 3.48 (2H, t, J=5.4Hz), 0.76–0.68 (2H, m), 0.48–0.43 (2H, m). 13C-NMR (126MHz,
2.59 (3H, s), 2.28 (1H, m), 0.71 (2H, m), 0.38 (2H, m). CDCl3) δ: 178.20, 159.69, 153.79, 151.00, 139.58, 132.34,
13C-NMR (126MHz, CDCl3) δ: 166.92, 158.86, 153.11, 148.47, 130.22, 126.26, 125.26, 124.21, 122.76, 122.14, 119.51, 115.84,
139.76, 139.71, 138.51, 126.38, 126.06, 125.27, 124.06, 122.91, 113.05, 112.15, 48.79, 41.32, 33.82, 31.16, 29.70, 22.49, 14.13,
121.36, 115.91, 113.47, 113.00, 48.81, 41.13, 31.16, 20.05, 7.95. 7.93. HPLC-MS: 7.74min, 488.2 (M+H+). HR-MS (ESI):
IR (KBr) cm−1: 1629.14, 1600.68, 1528.36, 1503.64, 1410.83, m/z (M+H+) Calcd for C24H24O2N3Cl2S: 488.0961. Found:
1331.04, 1229.17, 756.33. HPLC-MS: 6.02min, 471.2 (M+H+). 488.0951.
HR-MS (ESI): m/z (M+H+) Calcd for C22H20O4N4ClS:
471.0888. Found: 471.0875.
(4-(3-Chlorophenoxy)-2-isopropylthiazol-5-yl)(4-cy-
clopropyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone (37d)
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(2-meth- The title compound 37d was obtained as a light yellow solid
yl-4-(5-methyl-2-nitrophenoxy)thiazol-5-yl)methanone according to the procedure that preparation of the title com-
1
(32b) The title compound 32b was obtained as a light yellow pound 30i. mp 81°C. H-NMR (400MHz, CDCl3) δ: 7.12–7.06
solid according to the procedure that preparation of the title (1H, m), 7.02–6.92 (3H, m), 6.81 (1H, d, J=7.8Hz), 6.55–6.49
1
compound 32a. mp 94°C. H-NMR (300MHz, CDCl3) δ: 7.81 (3H, m), 3.92 (2H, t, J=5.6Hz), 3.36 (2H, t, J=5.5Hz), 3.17
(1H, d, J=6.3Hz), 6.97–6.88 (4H, m), 6.54 (1H, m), 6.16 (1H, (1H, p, J=6.9Hz), 2.35–2.28 (1H, m), 1.34 (6H, d, J=6.9Hz),
s), 3.95 (2H, t, J=4.2Hz), 3.47 (2H, t, J=4.2Hz), 2.56 (3H, s), 0.79–0.72 (2H, m), 0.49–0.44 (2H, m). 13C-NMR (126MHz,
2.28 (4H, m), 0.70 (2H, m), 0.38 (2H, m). 13C-NMR (126MHz, CDCl3) δ: 178.12, 159.89, 155.93, 154.48, 139.81, 134.30,
CDCl3) δ: 166.63, 163.28, 159.39, 154.38, 147.97, 145.65, 129.73, 126.14, 125.73, 123.52, 122.63, 118.33, 116.34, 115.86,

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Chem. Pharm. Bull.
Vol. 64, No. 4 (2016)
113.19, 112.14, 48.90, 41.64, 33.82, 31.24, 29.70, 22.50, 7.95. 126.33, 125.70, 125.25, 123.78, 122.75, 119.75, 118.67, 116.37,
HPLC-MS: 7.42min, 454.2 (M+H+). HR-MS (ESI): m/z 116.23, 115.68, 113.23, 48.92, 41.45, 31.21, 7.95. HPLC-MS:
(M+H+) Calcd for C24H25O2N3ClS: 454.1351. Found: 454.1349. 7.26min, 489.2 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-(2,5- C26H22O2N4ClS: 489.1147. Found: 489.1137.
dichlorophenoxy)-2-phenylthiazol-5-yl)methanone
(37e)
The title compound 37e was obtained as a yellow solid accord-
Acknowledgments This work was financially supported
ing to the procedure that preparation of the title compound by Grant from “National Science and Technology Major
1
30c. mp 136°C. H-NMR (400MHz, CDCl3) δ: 7.84–7.78 (2H, Project-Key New Drug Creation and Manufacturing program,
m), 7.47–7.37 (3H, m), 7.24 (1H, d, J=8.6Hz), 6.99–6.81 (4H, China” (2012ZX09103101-049) and National Nature Science
m), 6.55–6.47 (1H, m), 6.27 (1H, s), 3.98 (2H, t, J=5.5Hz), Foundation of China (Grant 81202571).
3.52 (2H, t, J=5.5Hz), 2.36–2.29 (1H, m), 0.77–0.69 (2H, m),
0.49–0.42 (2H, m). 13C-NMR (126MHz, CDCl3) δ: 166.87,
Conflict of Interest The authors declare no conflict of
159.42, 155.20, 150.94, 139.69, 132.54, 132.37, 131.11, 130.22, interest.
129.01, 126.41, 126.17, 125.38, 124.55, 122.73, 122.53, 120.07,
115.97, 113.10, 112.96, 48.82, 41.25, 31.14, 7.95. IR (KBr)
cm−1: 1639.69, 1472.36, 1407.45, 1336.07, 731.61. HPLC-MS:
8.15min, 522.2 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for
C27H22O2N3Cl2S: 522.0804. Found: 522.0800.
References
1) Vassileva G., Golovko A., Markowitz L., Abbondanzo S. J., Zeng
M., Yang S., Hoos L., Tetzloff G., Levitan D., Murgolo N. J., Keane
K., Davis H. R. Jr., Hedrick J., Gustafson E. L., Biochem. J., 398,
423–430 (2006).
(4-(3-Chlorophenoxy)-2-phenylthiazol-5-yl)(4-cyclo-
2) Tiwari A., Maiti P., Drug Discov. Today, 14, 523–530 (2009).
3) Keitel V., Gorg B., Bidmon H. J., Zemtsova I., Spomer L., Zilles K.,
Haussinger D., Glia, 58, 1794–1805 (2010).
4) Duboc H., Tache Y., Hofmann A. F., Dig. Liver Dis., 46, 302–312
(2014).
propyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone
(37f)
The title compound 37f was obtained as a yellow solid accord-
ing to the procedure that preparation of the title compound
1
30i. mp 123°C. H-NMR (400MHz, CDCl3) δ: 7.87–7.80 (2H,
m), 7.47–7.36 (3H, m), 7.12 (1H, t, J=7.9Hz), 7.06–6.93 (3H,
m), 6.86 (1H, d, J=7.9Hz), 6.59 (2H, d, J=8.4Hz), 6.56–6.48
(1H, m), 3.97–3.94 (2H, m), 3.40 (2H, t, J=5.6Hz), 2.38–2.30
(1H, m), 0.81–0.71 (2H, m), 0.51–0.43 (2H, m). 13C-NMR
(126MHz, CDCl3) δ: 166.81, 159.60, 155.85, 155.77, 139.92,
134.29, 132.61, 131.04, 129.72, 128.98, 126.28, 126.13, 125.85,
123.80, 122.58, 118.75, 116.44, 116.33, 113.24, 112.95, 48.94,
41.57, 31.22, 7.97. HPLC-MS: 7.05min, 488.2 (M+H+).
HR-MS (ESI): m/z (M+H+) Calcd for C27H23O2N3ClS:
488.1194. Found: 488.1186.
5) Watanabe M., Houten S. M., Mataki C., Christoffolete M. A., Kim
B. W., Sato H., Messaddeq N., Harney J. W., Ezaki O., Kodama
T., Schoonjans K., Bianco A. C., Auwerx J., Nature (London), 439,
484–489 (2006).
6) Katsuma S., Hirasawa A., Tsujimoto G., Biochem. Biophys. Res.
Commun., 329, 386–390 (2005).
7) Holst J. J., Physiol. Rev., 87, 1409–1439 (2007).
8) Fineman M. S., Cirincione B. B., Maggs D., Diamant M., Diabetes
Obes. Metab., 14, 675–688 (2012).
9) Knop F. K., Am. J. Physiol. Endocrinol. Metab., 299, E10–E13
(2010).
(4-Cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)(4-(2,5-
dichlorophenoxy)-2-(pyridin-2-yl)thiazol-5-yl)methanone
(37g) The title compound 37g was obtained as a yellow
solid according to the procedure that preparation of the title
compound 30c. mp 169°C. 1H-NMR (400MHz, CDCl3) δ:
8.60 (1H, d, J=5.0Hz), 7.90 (1H, d, J=7.9Hz), 7.72 (1H, t,
J=7.9Hz), 7.40–7.18 (2H, m), 7.03–6.77 (4H, m), 6.49 (1H, t,
J=7.5Hz), 6.21 (1H, s), 3.98 (2H, d, J=5.7Hz), 3.52 (2H, t,
J=5.4Hz), 2.32 (1H, s), 0.73 (2H, d, J=6.5Hz), 0.44 (2H, s).
13C-NMR (126MHz, CDCl3) δ: 167.27, 159.52, 155.16, 150.98,
150.06, 149.55, 139.70, 137.05, 132.38, 130.24, 126.46, 125.31,
125.24, 124.48, 122.88, 122.46, 119.88, 119.79, 115.91, 115.72,
113.09, 48.81, 41.13, 31.12, 7.93. IR (KBr) cm−1: 1627.25,
1471.82, 1398.62, 1230.21, 1075.35, 738.43. HPLC-MS:
7.44min, 523.2 (M+H+). HR-MS (ESI): m/z (M+H+) Calcd for
C26H21O2N4Cl2S: 523.0757. Found: 523.0747.
10) Kawamata Y., Fujii R., Hosoya M., Harada M., Yoshida H., Miwa
M., Fukusumi S., Habata Y., Itoh F., Shintani Y., Hinuma S., Fuji-
sawa Y., Fujino M., J. Biol. Chem., 278, 9435–9440 (2003).
11) Pellicciari R., Gioiello A., Macchiarulo A., Thomas C., Rosatelli
E., Natalini B., Sardella R., Pruzanski M., Roda A., Pastorini E.,
Schoonjans K., Auwerx J., J. Med. Chem., 52, 7958–7961 (2009).
12) Iguchi Y., Nishimaki-Mogami T., Yamaguchi M., Teraoka F.,
Kaneko T., Une M., Biol. Pharm. Bull., 34, 1–7 (2011).
13) Sato H., Genet C., Strehle A., Thomas C., Lobstein A., Wagner
A., Mioskowski C., Auwerx J., Saladin R., Biochem. Biophys. Res.
Commun., 362, 793–798 (2007).
14) Genet C., Strehle A., Schmidt C., Boudjelal G., Lobstein A.,
Schoonjans K., Souchet M., Auwerx J., Saladin R., Wagner A., J.
Med. Chem., 53, 178–190 (2010).
15) Ito F., Tawaraishi T., Hirohashi M., Matsumoto H., JP2006056881-A
(2006).
16) Dehmlow H., Alvarez Sanchez R., Bachmann S., Bissantz C., Bliss
F., Conde-Knape K., Graf M., Martin R. E., Obst Sander U., Raab
S., Richter H. G., Sewing S., Sprecher U., Ullmer C., Mattei P.,
Bioorg. Med. Chem. Lett., 23, 4627–4632 (2013).
17) Evans K. A., Budzik B. W., Ross S. A., Wisnoski D. D., Jin J.,
Rivero R. A., Vimal M., Szewczyk G. R., Jayawickreme C., Mon-
col D. L., Rimele T. J., Armour S. L., Weaver S. P., Griffin R. J.,
Tadepalli S. M., Jeune M. R., Shearer T. W., Chen Z. B., Chen L.,
Anderson D. L., Becherer J. D., De Los Frailes M., Colilla F. J., J.
Med. Chem., 52, 7962–7965 (2009).
(4-(3-Chlorophenoxy)-2-(pyridin-2-yl)thiazol-5-yl)(4-
cyclopropyl-3,4-dihydroquinoxalin-1(2H)-yl)methanone
(37h) The title compound 37h was obtained as a yellow
solid according to the procedure that preparation of the title
1
compound 30i. mp 142°C. H-NMR (400MHz, CDCl3) δ: 8.60
(1H, dt, J=4.8, 1.3Hz), 7.95–7.91 (1H, m), 7.72 (1H, td, J=7.8,
1.8Hz), 7.36–7.30 (1H, m), 7.13 (1H, t, J=8.0Hz), 7.05–6.93
(3H, m), 6.83 (1H, d, J=7.9Hz), 6.58 (2H, d, J=10.2Hz), 6.50
(1H, td, J=8.0, 7.3, 1.9Hz), 3.96 (2H, t, J=5.6Hz), 3.40 (2H,
t, J=5.6Hz), 2.38–2.30 (1H, m), 0.79–0.72 (2H, m), 0.49–0.42
(2H, m). 13C-NMR (126MHz, CDCl3) δ: 167.18, 159.72,
155.86, 150.16, 149.55, 139.93, 137.04, 134.34, 130.01, 129.77,
18) Piotrowski D. W., Futatsugi K., Warmus J. S., Orr S. T., Freeman-
Cook K. D., Londregan A. T., Wei L., Jennings S. M., Herr M.,
Coffey S. B., Jiao W., Storer G., Hepworth D., Wang J., Lavergne
S. Y., Chin J. E., Hadcock J. R., Brenner M. B., Wolford A. C.,

Vol. 64, No. 4 (2016)
Chem. Pharm. Bull.
339
Janssen A. M., Roush N. S., Buxton J., Hinchey T., Kalgutkar A. S.,
Sharma R., Flynn D. A., ACS Med. Chem. Lett., 4, 63–68 (2013).
19) Budzik B. W., Evans K. A., Wisnoski D. D., Jin J., Rivero R. A.,
S. A., Mangelsdorf D. J., Mol. Endocrinol., 25, 1066–1071 (2011).
24) Zou Q., Duan H., Ning M., Liu J., Feng Y., Zhang L., Zhu J., Leng
Y., Shen J., Eur. J. Med. Chem., 82, 1–15 (2014).
Szewczyk G. R., Jayawickreme C., Moncol D. L., Yu H., Bioorg. 25) Martin R. E., Bissantz C., Gavelle O., Kuratli C., Dehmlow H.,
Med. Chem. Lett., 20, 1363–1367 (2010).
Richter H. G., Obst Sander U., Erickson S. D., Kim K., Pietranico-
Cole S. L., Alvarez-Sanchez R., Ullmer C., ChemMedChem, 8,
569–576 (2013).
20) Futatsugi K., Bahnck K. B., Brenner M. B., Buxton J., Chin J. E.,
Coffey S. B., Dubins J., Flynn D., Gautreau D., Guzman-Perez A.,
Hadcock J. R., Hepworth D., Herr M., Hinchey T., Janssen A. M.,
Jennings S. M., Jiao W., Lavergne S. Y., Li B., Li M., Munchhof
M. J., Orr S. T. M., Piotrowski D. W., Roush N. S., Sammons M.,
Stevens B. D., Storer G., Wang J., Warmus J. S., Wei L., Wolford A.
C., MedChemComm, 4, 205–210 (2013).
26) Cottrell I. F., Hands D., Houghton P. G., Humphrey G. R., Wright S.
H. B., J. Heterocycl. Chem., 28, 301–304 (1991).
27) Buckle D. R., Rockell C. J. M., J. Chem. Soc., 627–630 (1982).
28) Baasner B., Schwamborn M., Santel H. J., Lurssen K., Schmidt R.,
US5057142-A (1991).
21) Londregan A. T., Piotrowski D. W., Futatsugi K., Warmus J. S.,
Boehm M., Carpino P. A., Chin J. E., Janssen A. M., Roush N. S.,
Buxton J., Hinchey T., Bioorg. Med. Chem. Lett., 23, 1407–1411
(2013).
22) Duan H., Ning M., Chen X., Zou Q., Zhang L., Feng Y., Zhang L.,
Leng Y., Shen J., J. Med. Chem., 55, 10475–10489 (2012).
23) Li T., Holmstrom S. R., Kir S., Umetani M., Schmidt D. R., Kliewer
29) Herbert J. M., Tetrahedron Lett., 45, 817–819 (2004).
30) Zhu J., Ning M., Guo C., Zhang L., Pan G., Leng Y., Shen J., Eur. J.
Med. Chem., 69, 55–68 (2013).
31) Zhu J., Ye Y., Ning M., Mandi A., Feng Y., Zou Q., Kurtan T., Leng
Y., Shen J., ChemMedChem, 8, 1210–1223 (2013).
32) Duan H., Ning M., Zou Q., Ye Y., Feng Y., Zhang L., Leng Y., Shen
J., J. Med. Chem., 58, 3315–3328 (2015).