Practical and Efficient Synthesis of 2-Thio-imidazole Derivative - ZY12201: A Potent TGR5 Agonist

Article abstract of DOI:10.1021/acs.oprd.0c00234

Early scalable process development for the synthesis of ZY12201, a novel TGR5 receptor agonist, as a potential clinical candidate is described. A practical, efficient, and scalable synthetic route provided ZY12201 in seven steps and 32% overall yield. The

Full text of DOI:10.1021/acs.oprd.0c00234

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Full Paper
Practical and Efficient Synthesis of 2-Thio-imidazole
derivative - ZY12201: A Potent TGR5 Agonist
Vivek M. Joshi, Chandrakant Sojitra, Santosh Sasane, Mrigendra Shukla, rakesh chauhan, vipin
chaubey, Sarika Jain, Kalpesh Shah, Hemant M. Mande, Shubhangi Sanjay Soman, Padmaja Sudhakar
Pamidimukkala, Shailesh Rajanikant Shah, Bipin Pandey, Kumar K Singh, and Sameer Agarwal
Org. Process Res. Dev., Just Accepted Manuscript • DOI: 10.1021/acs.oprd.0c00234 • Publication Date (Web): 30 Jul 2020
Downloaded from pubs.acs.org on July 31, 2020
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Practical and Efficient Synthesis of 2-Thio-imidazole derivative -
ZY12201: A Potent TGR5 Agonist
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Vivek M. Joshia,b, Chandrakant Sojitraa,b,c, Santosh Sasanea,b, Mrigendra Shuklaa, Rakesh Chauhana, Vipin
Chaubeya, Sarika Jaina, Kalpesh Shaha, Hemant Mandeb, Shubhangi Somanb, Padmaja Sudhakar
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Pamidimukkalab, Shailesh R. Shahb, Bipin Pandeya, Kumar K. Singhc, and Sameer Agarwala*
aZydus Research Centre, Cadila Healthcare Ltd., Sarkhej-Bavla N.H. No. 8 A, Moraiya, Ahmedabad - 382210, India
bDepartment of Chemistry, Faculty of Science, M.S.University of Baroda, Baroda - 390002, India;
cCadila Healthcare Limited, API Division, Sarkhej-Bavla N.H. No. 8 A, Changodar, Ahmedabad - 382210, India
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ABSTRACT: Early scalable process development for the
synthesis of ZY12201, a novel TGR5 receptor agonist as
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potential clinical candidate is described. A practical,
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efficient and scalable synthetic route had provided ZY12201
in 7-steps and 32% overall yield. The key step involves an
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inexpensive acetic acid mediated cyclization of thiourea 6
for the construction of 2-thio-imidazole derivative 7. In addition, an efficient process has been described
for synthesis of advance intermediates 2 and 10a that facilitated the synthesis of ZY12201. The developed
process demonstrated cost effective, high yielding, kilogram scalable and environmentally friendly
synthesis of ZY12201.This high yielding route enabled us to rapidly synthesize large quantities of
ZY12201 in 99% purity to support in vivo and toxicity studies.
KEYWORDS: TGR5, TGR5 agonist, type 2 diabetes, 2-thio imidazole, 1,2-dibromo ethane.
. INTRODUCTION
Diabetes is increasing at an alarming rate with approximately more than 463 million people affected
worldwide and the number of patients is expected to reach 700 million by the year 2045.1 Diabetes caused
at least USD 760 billion dollars in health expenditure in 2019, which is 10% of total spending on adults
treatment. With the rising incidence of obesity, a major risk factor for the onset of type 2 diabetes, this
metabolic disorder represents a major health concern and commonly termed as “Diabesity”.2 Although a
range of anti-diabetic agents are available, still there is high unmet medical need.3-5
Takeda G-protein-coupled receptor 5 (TGR5), also known as GPR 131, or GPBAR1, is a bile acid G
protein-coupled receptor primarily expressed in monocytes, macrophages, lung, spleen, intestinal tract
and is activated by bile acids.6,7 It has been suggested that bile acids induce glucagon-like peptide-1
(GLP-1) secretion from primary intestinal enteroendocrine cells by increasing intracellular cAMP levels
via the TGR5 receptor.8,9 Activation of TGR5 receptors in brown adipose tissue has been proposed to
increase energy expenditure through the induction of type 2 iodothyronine deiodinase (D2).10 Recent
studies suggest that the activation of TGR5 in macrophages may play a key role in the pathogenesis of
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atherosclerosis.11 TGR5 is being investigated as an attractive therapeutic target for the treatment of
obesity and its highly associated type 2 diabetes. Recently we have reported the identification of several
novel TGR5 agonists,12-13 including the discovery of 2-((2-(4-(1H-imidazol-1-yl)phenoxy)ethyl)thio)-5-
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(2-(3,4-dimethoxyphenyl)propan-2-yl)-1-(4-fluorophenyl)-1H-imidazole (ZY12201) as
a
potent,
selective, orally bioavailable and efficacious TGR5 agonist (Fig. 1).14 The 2-thio-imidazole derivative
ZY12201 was found to be highly potent TGR5 agonist (hTGR5 EC50 = 57 pM, mTGR5 = 62 pM) with
favorable pharmacokinetic profile. The compound was found to have excellent glucose lowering effects
in vivo during an oral glucose tolerance test in DIO C57BL/6 mice with ED50 of 7.9 mg/kg and ED90 of
29.2 mg/kg. Thus, an efficient synthetic route was needed to cater large quantities of ZY12201 to support
further preclinical studies including in vivo and toxicity studies.
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Figure 1. TGR5 receptor agonist.
Our original medicinal chemistry synthesis of ZY12201 (Scheme 1),14-15 began with commercially
available 2-(3,4-dimethoxyphenyl) acetonitrile. Key intermediate 2 was obtained from 2-(3,4-
dimethoxyphenyl) acetonitrile via a 4-step sequence in 56% overall yield. Other synthetic routes of 2
involved harsh conditions, multi-step synthesis with cumbersome work up, difficult product isolation and
unsatisfactory yields.16 Moreover, the original approach involved high manufacturing costs due to the
application of expensive raw materials and reagents. Loss of significant component of the API during
column chromatographic purification also attributes to the higher costs. In addition, many of these
reactions were not feasible on multi 100 g scale. Thus, further work on technical improvements to
overcome the limitations was still a crucial experimental challenge. This report describes our synthetic
and process chemistry efforts towards the development of a practical, efficient and scalable process for
synthesis of TGR5 agonist ZY12201 to support preclinical studies.
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Scheme 1. Original synthesis of ZY12201. Reagent and Conditions: (a) MeI, NaH, THF, 0 ºC to r.t., 3 h, 93%;
(b) DIBAL, Toluene, -78 ºC, 2 h, 93%; (c) MeMgBr, dry Et2O, 0 ºC to r.t., 80%; (d) oxalyl chloride, DMSO, Et3N,
DCM, -78 ºC, 2 h, 82%; (e) Bu4NBr3, DCM, MeOH, 0 ºC to r.t., 7 h, 100%; (f) HMTA, DCM, r.t., 48 h; (g) EtOH,
HCl, 80 ºC, 3 h; (h) 1-fluoro-4-isothiocyanatobenzene, Et3N, DCM, 0 ºC to r.t., 1 h, 42%; (i) AcOH, 118 ºC, 3 h,
73%; (j) 1,2-dibromoethane, K2CO3, acetone, r.t., 2 h, 73%; (k) 4-(1H-imidazol-1-yl)phenol, K2CO3, DMF, 90 ºC, 5
h, 73%.
. RESULTS AND DISCUSSION
The optimized synthesis of ZY12201 began with an inexpensive commercially available 2-(3,4-
dimethoxyphenyl)acetone (1) as depicted in Scheme 2. An efficient dimethylation of 1 using excess of
methyl iodide afforded desired intermediate 2 in one-step with 93% yield, purified by filtration over short
path of silica gel. Subsequently, alpha-bromination17 of compound 2, using tetrabutyl
ammoniumtribromide afforded bromo compound 3, on multi gram scale in quantitative yield. As shown
in Scheme 1, 3 was directly converted into 5 using HMTA (hexamethylenetetramine) followed by
treatment with hydrochloric acid. However, the reaction was generally low yielding and generated several
unknown impurities which were difficult to remove, thus complicating the subsequent step. To
circumvent difficulties associated with this reaction, 3 was first transformed to azide 4 which upon
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hydrogenation provided amine 5 as its corresponding hydrochloride salt. Importantly here, the solid
product was filtered and washed with diisopropyl ether to provide 5 in high purity (93% by HPLC) and
excellent yield (96%), on 120 g scale. We recommend appropriate safety measures, such as a closed
delivery system, personal protective equipment and protective nitrile gloves should be used while
handling sodium azide on a large scale.18-19
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Scheme 2. Optimized synthesis of ZY12201. Reagent and Conditions: (a) MeI, NaH, dry THF, 0 ºC to r.t., 3 h,
93%; (b) Bu4NBr3, DCM, MeOH, 0 ºC to r.t., 7 h, 100%; (c) NaN3, DMF, 0 ºC to r.t., 2 h, 94%; (d) Pd/C, H2 (gas),
HCl, MeOH, r.t., 45 h, 96%; (e) 1-fluoro-4-isothiocyanatobenzene, Et3N, DCM, 0 ºC to r.t., 18 h, 61%; (f) AcOH,
reflux, 3 h, 77%; (g) 10a, K2CO3, acetone, r.t., 2 h, 80%.
Treatment of amine 5 with 1-fluoro-4-isothiocyanatobenzene provided thiourea derivative 6. The thiourea
formation step suffered from variable yields (<40-60%) and incomplete conversion, often stalling at 40-
55% conversion. During the optimization of this reaction, we varied amount of 1-fluoro-4-
isothiocyanatobenzene and the reaction conditions. Charging additional reagent (1-fluoro-4-
isothiocyanato benzene) or base (triethyl amine) did not improve conversion, and solvent switch from
dichloromethane to acetone resulted in low yield with concomitant formation of black polymeric material.
Interestingly, lower equimolar concentration of regent still gave high product yield with extended reaction
time (1.0 equivalent of 1-fluoro-4-isothiocyanatobenzene, 18 h, 61% of 6). The key step in our synthetic
route was the cyclization of thiourea (6) using inexpensive acetic acid for the construction of imidazole
skeleton.20 Treatment of thiourea (6) in boiling acetic acid led to the facile cyclization which afforded 2-
thio imidazole derivative 7. The workup protocol and purification process were optimized; the reaction
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mixture was cooled to room temperature and slowly poured onto ice-water with gentle stirring, instead of
directly using ice with vigorous stirring. The slow addition of the reaction mixture onto ice minimizes the
exotherm of the quench, thus minimizing product decomposition. The mixture was extracted with ethyl
acetate and washed with saturated sodium bicarbonate solution and brine to afford crude compound as
brown solid. Reprecipitation of the crude product with solvents like ethyl acetate and n-hexane resulted
compound 7 with an improved yield of 77% and in high chemical purity (98% by HPLC).
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N
b
N
X
N
a
N
OH
N
O
NH
10a (X = Br)
10b (X = Cl)
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Scheme 3. Synthesis of Compound 10. Reagent and Conditions: (a) 4-bromo phenol, CuI, Cs2CO3, DMF, 110°C,
48 h, 67%; (b) 1,2-dihalogenethane, K2CO3, MeCN, 65°C, 24 h, (84% for 10a; 60% for 10b).
Table 1: Optimization of the alkylation reaction: Effects of increasing amount of 1,2-dibromoethane on the
preparation of compound 10a.
Entry
1,2-dibromoethane
10a, %Yield
(equivalents)
1
2
3
4
4
40
64
84
78
20
40
80
The initial14 synthesis of ZY12201, used the alkylation of 7 with 1,2-dibromo ethane. This route was
particularly designed to explore SAR, as this compound serves as an excellent intermediate for
synthesizing a wide variety of analogues. However, this reaction was found to be low yielding on large
scale with formation of many uncharacterized impurities. Due to the poor results obtained, we next
decided to examine the alkylation of 4-(1H-imidazol-1-yl)phenol (9) with 1,2-dibromo ethane to give
intermediate 10a. A highly effectual synthesis of novel intermediate 10a was needed to accomplish the
synthesis of ZY12201. Towards this end, various experimental conditions were explored. Commercially
available imidazole (8) was converted to 4-(1H-imidazol-1-yl)phenol (9) on large scale using Buchwald-
Hartwig21 conditions. Phenol (9) was transformed to bromo intermediate 10a using 1,2-dibromo ethane in
the presence of potassium carbonate (Scheme 3). Gratifyingly, when the amount of 1,2-dibromo ethane
was increased to 40 equivalents, the yield was improved from 40% to 84% (Table 1, entries 1-3), but
further increase of 1,2-dibromo ethane did not improve the yield (entry 4). Having key intermediates 7
and 10a in hand, finally alkylation of 7 with 10a provided ZY12201 in excellent yield and high chemical
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purity. Alternatively, alkylation of 7 with chloro derivative 10b was also investigated, which afforded the
final compound in best yield of 55% (using 20 equivalents of 10b), on gram scale. However, this reaction
for synthesis of ZY12201 was not feasible on large scale due to formation of many uncharacterized
impurities. The structure of ZY12201 has been unequivocally confirmed by the X-ray crystal structure
determination (Fig. 2). Additionally, the procedure opens up the way to an efficient and scalable synthesis
of wide range 2-thio-imidazole analogues for structure–activity studies.
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Figure 2. Single crystal X-ray analysis of 2-((2-(4-(1H-imidazol-1-yl)phenoxy)ethyl)thio)-5-(2-(3,4-
dimethoxyphenyl)propan-2-yl)-1-(4-fluorophenyl)-1H-imidazole (ZY12201).
Compared with the reported synthesis, our optimized sequence was shortened from 11 steps to 7 steps,
and the overall yield was significantly improved from 9% to 32%, on multi gram scale. Key to success of
this approach was the identification of an efficient and practical synthesis of intermediates 2 and 10a as
well as the removal of column chromatography purification of several advanced intermediates.
. CONCLUSION
In conclusion, an efficient and scalable synthesis of a potent, selective and orally bioavailable TGR5
agonist ZY12201 has been described. The process involves an inexpensive acetic acid mediated
cyclization of thiourea (6) to the corresponding 2-thio imidazole derivative (7), as a key step. A highly
practical and convenient process was found for synthesis of advance intermediates 2 and 10a that
facilitated the synthesis of ZY12201. The original 11-step synthesis of ZY12201 was replaced by a robust
7-step route affording the target in 32% yield. Major highlights of our practical and scalable process
includes higher overall yield, simplified reaction workup; and no usage of chromatography which resulted
in huge reduction in the total solvent consumption, considering as an important parameter for green
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chemistry Taken together, we have developed a process that is cost effective, environment friendly and
commercially viable synthesis of TGR5 agonist ZY12201, leading to extensive prospects in industrial
applications.
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. EXPERIMENTAL SECTION
General Methods. Melting points were recorded on a scientific melting point apparatus and are
uncorrected. IR spectra were recorded as neat (for oils) or on KBr pellet (for solid) on FT-IR 8300
Shimadzu and are reported in wavenumbers ν (cm-1). NMR spectra were measured on a Varian Unity 400
(1H at 400 MHz, 13C at 100 MHz), magnetic resonance spectrometer. Spectra were taken in the indicated
solvent at ambient temperature. Chemical shifts (δ) are given in parts per million (ppm) with
tetramethylsilane as an internal standard. Multiplicities are recorded as follows: s = singlet, d = doublet, t
= triplet, q = quartet, br = broad. Coupling constants (J values) are given in Hz. Mass spectra were
recorded on Perkin-Elmer Sciex API 3000. ESI-Q-TOF-MS measurements were performed with a
micrOTOF-Q II (Bruker Daltonics) mass spectrometer. HPLC analysis were carried out at λmax 220 nm
using column ODS C-18, 150 mm x 4.6 mm x 4 μm on AGILENT 1100 series. Reactions were monitored
using thin layer silica gel chromatography (TLC) using 0.25 mm silica gel 60F plates from Merck. Plates
were visualized by treatment with UV, acidic p-anisaldehyde stain or KMnO4 stain with gentle heating.
Products were purified by column chromatography using silica gel 100-200 mesh and the solvent systems
indicated. All reactions involving air or moisture sensitive compounds were performed under nitrogen
atmosphere in flame dried glassware. Solvents used for reactions were purified according to standard
procedures. Starting reagents were purchased from commercial suppliers and used without further
purification unless otherwise specified. All yields are reported before correction for compound purity.
3-(3,4-dimethoxyphenyl)-3-methylbutan-2-one (2): A 500 mL, four-neck, round-bottom flask equipped
with a mechanical stirrer and thermometer pocket was charged with THF (160 mL) and cooled externally
o
to -5-0 C under nitrogen atmosphere. Sodium hydride (9.88 g, 0.247 mol, 50-55% in mineral oil) was
added portion wise followed by addition of 1-(3,4-dimethoxyphenyl)propan-2-one (20 g, 0.103 mol) at 0
oC and stirred at 0-5 oC for 30 minutes. Methyl iodide (43.85 g, 19.3 mL, 0.309 mol) was added drop wise
o
at 0 C over a period of 1 h. The reaction mixture was warmed to room temperature and stirred for 2 h
then dumped onto ice water (200 mL) at 0-5 oC. The reaction mixture was extracted with ethyl acetate (2
x 100 mL). The combined organic layer was washed with 5% Na2SO3 solution (3 x 50 mL), water (2 x
100 mL) and brine (1 x 200 mL), treated with activated charcoal (2 g) and filtered through HyFlo
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SuperCel. The filtrate was concentrated in vacuo to afford crude product (~ 28 g). The crude product was
purified by filtration over short path of silica gel using 6% ethyl acetate/n-hexane as eluent to furnish
compound 2 (21.3 g, 93%) as an oil.
1
% purity: 97.73% (HPLC); H NMR (CDCl3, 400 MHz) δ: 1.47 (s, 6H), 1.93 (s, 3H), 3.86 (s, 3H), 3.87
(s, 3H), 6.70 (s, 1H), 6.84 (s, 2H); 13C NMR (CDCl3, 100 MHz) δ: 25.26, 25.41, 52.11, 55.99, 56.05,
109.63, 111.34, 119.05, 136.72, 148.12, 149.19, 211.48; IR (KBr): ν = 770, 810, 1028, 1258, 1466, 1516,
1589, 1705, 2835, 2936, 2972 cm-1; ESI-MS (m/z): 223.0 [M + H]+.
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1-bromo-3-(3,4-dimethoxyphenyl)-3-methylbutan-2-one (3): To a solution of compound 2 (117 g,
0.526 mol) in dichloromethane (1.17 L) and methanol (0.585 L) was added tetra butyl ammonium
tribromide (269 g, 0.557 mol) in one portion at 0 oC. The mixture was stirred for 2 h at 0 oC, then warmed
to room temperature and stirred for 16 h. The reaction mixture was concentrated in vacuo. The residue
was dissolved in ethyl acetate (1.17 L), and washed with water (2 x 1.17 L), 1M HCl (0.585 L), and brine
(1.17 L). The organic layer was dried over sodium sulphate, filtered and concentrated in vacuo to afford a
light brown color oil which was triturated with n-hexane to afford 3 (158.4 g, 100%).
1
% purity: 85.97% (HPLC); H NMR (CDCl3, 400 MHz) δ: 1.54 (s, 6H), 3.87 (s, 2H), 3.89 (s, 3H), 3.90
(s, 3H), 6.68 (d, J = 2.0 Hz, 1H), 6.82 – 6.88 (m, 2H); 13C NMR (CDCl3, 100 MHz) δ: 25.47, 32.01,
51.91, 55.98, 56.05, 109.49, 111.52, 119.08, 135.09, 148.51, 149.39, 204.13; IR (CHCl3): ν = 762, 1026,
1216, 1258, 1518, 1591, 1724, 2839, 2976, 3021 cm-1.
1-azido-3-(3,4-dimethoxyphenyl)-3-methylbutan-2-one (4): To a solution of compound 3 (139 g, 0.462
mol) in DMF (417 mL) was added sodium azide (39 g, 0.6 mol) in one portion at 0 oC and stirred for 30
minutes. The mixture was then warmed to room temperature and stirred for 2 h. The reaction mixture was
dumped onto water (2.5 L) and stirred for 15 minutes. The mixture was extracted with ethyl acetate (3 x
1.4 L). The combined organic layer was washed with water (1.4 L) and brine (1.4 L), treated with
activated charcoal and filtered through HyFlo SuperCel. The filtrate was concentrated in vacuo to afford 4
(138 g, 94%) as an oil which was used in next reaction without further purification. (We recommend
appropriate safety measures, such as a closed delivery system, personal protective equipment and
protective nitrile gloves should be used while handling sodium azide on a large scale.)
1H NMR (DMSO-d6, 400 MHz) δ: 1.45 (s, 6H), 3.70 (s, 3H), 3.74 (s, 3H), 4.05 (s, 2H), 6.75 – 6.82 (m,
2H), 6.96 (d, J = 7.2 Hz, 1H); 13C NMR (DMSO-d6, 100 MHz) δ: 24.67, 50.10, 53.19, 55.43,
55.47,110.03, 111.84, 118.22, 134.95, 147.92, 148.76, 207.63.
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1-amino-3-(3,4-dimethoxyphenyl)-3-methylbutan-2-one hydrochloride (5): To
a solution of
compound 4 (121.5 g, 0.461 mol) in methanol (2.43 L) was added concentrated hydrochloric acid (69.2
mL, 0.85 mol) and 10% palladium on activated charcoal (50% moisture) (1.6 mol%) at room temperature.
The reaction mixture was flushed with hydrogen gas and was stirred at room temperature under hydrogen
gas atmosphere for 45 h. After completion of reaction, filtered through HyFlo SuperCel, and concentrated
in vacuo to afford crude product. Diisopropyl ether (2.43 L) was added to the crude product and the solid
mixture was stirred for 1 h at room temperature. The solid product was filtered in vacuo and washed with
diisopropyl ether (3 x 500 mL). The product was dried for 1 h to yield 5 (121 g, 96%) as a pale yellow
solid.
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% purity: 92.82% (HPLC); H NMR (DMSO-d6, 400 MHz) δ: 1.47 (s, 6H), 3.75 (s, 3H), 3.76 (s, 3H),
3.77 (s, 2H), 6.78 (d, J = 2.4 Hz, 1H), 6.84 – 6.96 (m, 2H), 8.2 (br s, 2H); 13C NMR (DMSO-d6, 100
MHz) δ: 24.92, 43.39, 49.78, 55.55, 55.58, 110.36, 111.85, 118.33, 134.88, 148.01, 148.77, 206.28; ESI-
MS (m/z): 238.1 [M + H]+.
1-(3-(3,4-dimethoxyphenyl)-3-methyl-2-oxobutyl)-3-(4-fluorophenyl)thiouea (6):To a solution of 5
(49 g, 0.179 mol) in dichloromethane (490 mL) was added triethylamine (54.3 g, 74.8 mL, 0.537 mol) at
o
0 C under nitrogen atmosphere. A solution of 1-fluoro-4-isothiocyanato benzene (27.4 g, 0.179 mol) in
dichloromethane (190 mL) was added using dropping funnel to the reaction mixture at 0 oC under stirring.
The cooling bath was removed and the mixture was stirred at room temperature for 18 h. Reaction
mixture was diluted with dichloromethane (490 mL) and quenched with water (350 mL). Organic layer
was separated and washed with water (3 x 350 mL) and dried over sodium sulfate, filtered and
concentrated in vacuo to afford crude compound as light brown solid. The crude solid was stirred with
diisopropyl ether (490 mL) at room temperature for 16 h. The solid product was filtered and dried in
vacuo to afford compound 6 (42.6 g, 61%) as pale yellow solid.
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% purity: 95.90% (HPLC); H NMR (CDCl3, 400 MHz) δ: 1.53 (s, 6H), 3.85 (s, 3H), 3.86 (s, 3H), 4.38
(d, J = 4.4 Hz, 2H), 6.70 (s, 2H), 6.83 (s, 2H), 7.12 – 7.17 (m, 2H), 7.21 – 7.26 (m, 2H), 7.84 (br s, 1H);
13C NMR (CDCl3, 100 MHz) δ: 25.41, 50.25, 50.88, 56.03, 56.16, 109.64, 111.54, 117.20, 117.83,
118.45, 127.57, 127.66, 134.91, 148.59, 149.36, 180.53, 208.43; IR (KBr): ν = 800, 1040, 1215, 1258,
1510, 1545, 1726, 2926, 2965, 3167, 3333, 3433 cm-1; ESI-MS (m/z) (%): 391.1 (100%) [M + H]+.
5-(2-(3,4-dimethoxyphenyl)propan-2-yl)-1-(4-fluorophenyl)-1H-imidazole-2-thiol (7). A mixture of 6
(80 g, 0.204 mol) and acetic acid (800 mL) was heated at reflux temperature for 3 h. The reaction mixture
was cooled to room temperature and poured onto ice-water (4000 mL) with gentle stirring. The mixture
was extracted with ethyl acetate (2 x 1.12 L). The combined organic layer was washed with saturated
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sodium bicarbonate solution (3 x 1.12 L) and brine (1.12 L). The organic layer was dried over sodium
sulphate, filtered and concentrated in vacuo to afford crude compound as brown solid. The crude solid
was stirred with 20% ethyl acetate/n-hexane (560 mL) at room temperature for 16 h. The solid product
was filtered and dried in vacuo to afford compound (7) (59 g, 77%) as off-white solid.
% purity: 97.91% (HPLC); 1H NMR (CDCl3, 400 MHz) δ: 1.44 (s, 6H), 3.75 (s, 3H), 3.87 (s, 3H), 6.45 –
6.48 (m, 2H), 6.58 – 6.62 (m, 2H), 6.67 (d, J = 8.0 Hz, 1H), 6.79 (s, 1H), 6.87 (t, J = 8.8 Hz, 2H), 12.01
(br s, 1H); 13C NMR (CDCl3, 100 MHz) δ: 29.29, 38.07, 56.02, 56.10, 109.61, 110.93, 111.27, 111.85,
115.67, 118.48, 131.61, 132.69, 138.21, 140.34, 147.91, 148.85, 162.38 (d, JC,F = 248 Hz); IR (KBr): ν =
797, 1026, 1215, 1265, 1512, 1599, 2720, 2835, 2932, 3051, 3464 cm-1; ESI-MS (m/z) (%): 373.1 (100%)
[M + H]+.
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4-(1H-imidazol-1-yl)phenol (9). In a 5 L glass assembly (equipped with a condenser and a thermometer
pocket) was charged DMF (1.4 L), 1H-imidazol (82 g, 1.20 mol), 4-bromophenol (250 g, 1.445 mol),
copper iodide (45.86 g, 0.241 mol) and cesium carbonate (784.9 g, 2.409 mol) at a room temperature. The
mixture was heated at 100-110 oC and stirred for 48 h. The mixture was cooled to room temperature. The
reaction mixture was diluted with mixture of ethyl acetate and methanol (1:1) (3 L) and filtered through
HyFlo SuperCel. The filtrate was concentrated in vacuo to afford brown colour oily mass. The oily mass
was stirred with 1N HCl solution (2.5 L) for 15 minutes, then mixture was extracted by ethyl acetate (3 x
1 L). The aqueous layer was basified with saturated sodium bicarbonate solution. The precipitated product
was filtered, washed with water and dried in vacuo to afford crude compound (~ 200 g). The crude solid
was stirred with acetonitrile (200 mL) for 30 minutes at room temperature. The solid product was filtered
and dried in vacuo to afford titled compound 9 (130 g, 67%) as white solid.
% purity: 99.23% (GC); 1H NMR (DMSO-d6, 400 MHz) δ: 6.86 - 6.90 (m, 2H), 7.08 (s, 1H), 7.39 - 7.43
(m, 2H), 7.58 (s, 1H), 8.08 (s, 1H), 9.80 (s, 1H); 13C NMR (DMSO-d6, 100 MHz) δ: 116.0, 118.0, 122.0,
129.0, 129.4, 137.0, 156.4; ESI-MS (m/z): 161.0 [M + H]+.
General procedure for synthesis of compound (10a-b)
To a stirred solution of 4-(1H-imidazol-1-yl)phenol (9) (25 g, 0.156 mol) in acetonitrile (300 mL) was
added potassium carbonate (108 g, 0.780 mol) in one portion at room temperature. The mixture was
stirred for 15 minutes at room temperature. A solution of 1,2-dihalo ethane (0.624 mol, 4 eq.) in
o
acetonitrile (30 mL) was added dropwise and stirred the reaction mixture at 60-65 C for 24 h. The
mixture was cooled to 25-30 oC, filtered and concentrated in vacuo to afford oily mass. The oily mass was
stirred with 1N HCl (350 mL) for 15 minutes and then mixture was extracted by ethyl acetate (3 x 100
mL). The aqueous layer was basified with 2N NaOH solution. The aqueous layer was extracted by diethyl
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ether (3 x 200 mL) and washed by brine solution (100 mL). The organic layer was concentrated in vacuo
to afford compound (10a-b) as oil.
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1-(4-(2-bromoethoxy)phenyl)-1H-imidazole (10a). The compound 10a was synthesized following the
general procedure described for compound (10a-b), using 40 equivalents of 1,2-dibromo ethane. The
compound 10a was obtained as a dark brown oil (35 g, 84% yield) which was used for next reaction
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without any further purification. H NMR (DMSO-d6, 400 MHz) δ: 3.81 (t, J = 5.6 Hz, 2H), 4.36 (t, J =
5.6 Hz, 2H), 7.06 – 7.08 (m, 1H), 7.09-7.11 (m, 2H), 7.53 - 7.57 (m, 2H), 7.64 – 7.65 (t, J = 1.2 Hz, 1H),
8.13 (d, J = 0.8 Hz, 1H); 13C NMR (DMSO-d6, 100 MHz) δ: 31.39, 68.11, 115.90, 118.84, 121.99,
129.57, 131.31, 135.51, 156.64; ESI-MS (m/z): 268.9 [M + H]+.
1-(4-(2-chloroethoxy)phenyl)-1H-imidazole (10b). The compound 10b was synthesized following the
above general procedure described for compound (10a-b). The compound 10b was obtained as a dark
1
brown oil (21 g, 60% yield). % purity: 87.44% (HPLC); H NMR (CDCl3, 400 MHz) δ: 3.83 (t, J = 5.6
Hz, 2H), 4.26 (t, J = 5.6 Hz, 2H), 6.98 - 7.02 (m, 2H), 7.18 (s, 1H), 7.20 (s, 1H), 7.28 – 7.32 (m, 2H), 7.76
(d, J = 0.8 Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ: 41.82, 68.43, 115.78, 118.70, 123.23, 130.14, 131.31,
135.80, 157.53; ESI-MS (m/z): 223.0 [M + H]+.
2-((2-(4-(1H-imidazol-1-yl)phenoxy)ethyl)thio)-5-(2-(3,4-dimethoxyphenyl)propan-2-yl)-1-(4-fluoro
phenyl)-1H-imidazole (ZY12201). A mixture of compound 7 (9 g, 0.024 mol), 1-(4-(2-
bromoethoxy)phenyl)-1H-imidazole (10a) (12.9 g, 0.048 mol), potassium carbonate (10.0 g, 0.072 mol)
in acetone (100 mL) was stirred at room temperature for 2 h. Reaction mixture was diluted with acetone
(90 mL), filtered and concentrated in vacuo to afford crude product (~19.5 g). The crude product was
purified by a short column chromatography over silica gel with 1-3% methanol/chloroform as eluent to
furnish compound ZY12201 (11.95 g, 80%) as white solid.
White powder; mp: 108 ºC; % purity: 99.57%; 1H NMR (400 MHz, DMSO-d6): δ = 1.49 (s, 6H), 3.42 (t,
J = 6.4 Hz, 2H), 3.72 (s, 3H), 3.84 (s, 3H), 4.27 (t, J = 6.4 Hz, 2H), 6.49 – 6.55 (m, 4H), 6.64 (d, J = 8.8
Hz, 1H), 6.80 - 6.85 (m, 2H), 6.98 – 7.00 (m, 2H), 7.15 (s, 1H), 7.18 – 7.20 (m, 2H), 7.27 – 7.29 (m, 2H),
7.77 (br s, 1H); 13C NMR and DEPT (100 MHz, DMSO-d6): δ = 29.61 (CH3), 31.54 (CH2), 38.12 (C),
55.99 (CH3), 56.05 (CH3), 67.17 (CH2), 109.96 (CH), 110.83 (CH), 115.38 (CH), 115.61 (CH), 115.75
(CH), 118.45 (CH), 118.84 (CH), 123.22 (CH), 125.99 (CH), 130.01 (C), 130.97 (CH), 131.06 (C),
132.07 (C), 139.89 (C), 143.37 (C), 144.18 (C), 147.58 (C), 148.70 (C), 157.89 (C), 162.49 (C) (d, JC,F
=
248 Hz); MS (EI): m/z (%) = 559.1 (100%) (M)+, 560.5 (M+H)+; ESI-Q-TOF-MS: m/z [M+H]+ calcd for
[C31H31FN4O3S + H]+: 559.2134; found: 559.2244; IR (KBr): ν = 3495, 3367, 3063, 2931, 2829, 1602,
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1462 cm-1; Anal. Calcd for C31H31FN4O3S: C, 66.68; H, 5.59; N, 10.02; S, 5.73. Found: C, 66.48; H, 5.95;
N, 9.73; S, 5.66.
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. ASSOCIATED CONTENT
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Supporting Information
The supporting information is available free of charge via the Internet at http://pubs.acs.org
Spectral data and X-Ray data file
. AUTHOR INFORMATION
Corresponding Author
* E-mail: sameeragarwal@zyduscadila.com; or Sameer_ag@yahoo.com (SA).
ORCID:
Sameer Agarwal: 0000-0002-7039-3028
Notes
The authors declare no competing financial interest.
ZRC Communication No. 654.
. ACKNOWLEDGEMENT
Authors thank Jiger Gajjar, Jignesh Chauhan, Timir Patel, Bansari Patel, Prashant Kapse, Dipak Patel,
and Naynish Trivedi from analytical department.
. REFERENCES
(1) IDF Diabetes Atlas, 9th ed.; International Diabetes Federation: Brussells, Belgium, 2019;
http://www.diabetesatlas.org.
(2) Farag, Y. M.; Gaballa, M. R. Diabesity: An overview of a rising epidemic. Nephrol Dial
Transplant. 2011, 26, 28-35.
(3) Doyle, M. E.; Egan, J. M. Pharmacological agents that directly modulate insulin secretion.
Pharmacol. Rev. 2003, 55, 105-131.
(4) Ashiya, M.; Smith, R. E. T. Non-insulin therapies for type 2 diabetes. Nat. Rev. Drug Discovery
2007, 6, 777-778.
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(5) Agarwal S.; Sasane, S.; Deshmukh, P.; Rami, B.; Bandyopadhyay, D.; Giri, P.; Giri, S.; Jain, M.;
Desai. R. C. Identification of an orally efficacious GPR40/FFAR1 receptor agonist. ACS Med.
Chem. Lett. 2016, 7 (12), 1134–1138.
7
8
9
(6) Maruyama, T.; Miyamoto, Y.; Nakamura, T.; Tamai, Y.; Okada, H.; Sugiyama, E.; Itadani, H.;
Tanaka, K. Identification of membrane-type receptor for bile acids (M-BAR), Biochem. Biophys.
Res. Commun. 2002, 298, 714-719.
10
11
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(7) Tiwari, A.; Maiti, P. TGR5: an emerging bile acid G-protein-coupled receptor target for the
potential treatment of metabolic disorders. Drug Discovery Today 2009, 14, 523-530.
(8) Katsuma, S.; Hirasawa, A.; Tsujimoto, G. Bile acids promote glucagon-like peptide-1 secretion
through TGR5 in a murine enteroendocrine cell line STC-1. Biochem. Biophys. Res. Commun.
2005, 329, 386-390.
(9) Thomas, C.; Gioiello, A.; Noriega, L.; Strehle, A.; Oury, J.; Rizzo, G.;Macchiarulo, A.;
Yamamoto, H.; Mataki, C.; Pruzanski, M.; Pellicciari, R.; Auwerx, J.; Schoonjans, K. TGR5-
mediated bile acid sensing controls glucose homeostasis. Cell Metab. 2009, 10, 167-177.
(10) 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.
Bile acids induce energy expenditure by promoting intracellular thyroid hormone activation.
Nature 2006, 439, 484-489.
(11) Pols, T. W. H.; Nomura, M.; Harach, T.; Lo Sasso, G.; Oosterveer, M. H.; Thomas, C.; Rizzo,
G.; Gioiello, A.; Adorini, L.; Pellicciari, R.; Auwerx, J.; Schoonjans, K. TGR5 activation inhibits
atherosclerosis by reducing macrophage inflammation and lipid loading. Cell Metab. 2011, 14,
747-757.
(12) Agarwal, S.; Sasane, S.; Kumar, J.; Darji, B.; Bhayani, H.; Soman, S.; Kulkarni, N.; Jain, M.
Novel 2-Mercapto imidazole and triazole derivatives as potent TGR5 receptor agonists. Medicine
in Drug Discovery 2019, 1, 100002.
(13) Agarwal, S.; Sasane, S.; Kumar, J.; Deshmukh, P.; Bhayani, H.; Giri, P.; Giri, S.; Soman, S.;
Kulkarni, N.; Jain, M. Evaluation of novel TGR5 agonist in combination with Sitagliptin for
possible treatment of type 2 diabetes. Bioorg. Med. Chem. Lett. 2018, 28, 1849-1852.
(14) Agarwal, S.; Patil, A.; Aware, U.; Deshmukh, P.; Darji, B.; Sasane, S.; Sairam, K. V. V. M.;
Priyadarsiny, P.; Giri, P.; Patel, H.; Giri, S.; Jain, M.; Desai. R. C. Discovery of a potent and
orally efficacious TGR5 receptor agonist. ACS Med. Chem. Lett. 2016, 7 (1), 51–55.
(15) Agarwal, S.; Jain, M. R.; Patel, P. R. 2-Thio-imidazole derivatives as TGR5 modulators. PCT
Int. Appl. WO 2013/054338, 18 April 2013 (Appl. PCT/IN2012/000471, 4.07.2012).
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(16) Finkelstein, J.; Chiang, E.; Brossi, A. Synthesis of 1,2,3,4-tetrahydro-1,1,2,3,3,4,4-heptamethyl-
6,7-dimethoxyisoquinoline and related compounds as potential hypotensive agents. J. Med.
Chem. 1971, 14(7), 584-8.
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8
9
(17) Jagatheesan, R.; Ramesh, P.; Sambathkumar, S. Selective α-bromination of aryl carbonyl
compounds: prospects and challenges, Synthetic Communications 2019, 25, 3265-3289.
(18) Gonzalez-Bobes, F.; Kopp, N.; Li, L.; Deerberg, J.; Sharma, P.; Leung, S.; Davies, M.; Bush, J.;
Hamm, J.; Hrytsak, M. Scale-up of azide chemistry: A case study. Org. Process Res. Dev. 2012,
16, 2051−2057.
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60
(19) Conrow, R. E.; Dean, W. D. Diazomethane Explosion. Org. Process Res Dev. 2008, 12, 1285–
1286.
(20) Maeda, S.; Suzuki, M.; Iwasaki, T.; Matsumoto, K; Iwasawa, Y. Syntheses of 2-mercapto-4-
substituted imidazole derivatives with antiinflammatory properties. Chem. Pharm. Bull. 1984, 32
(7), 2536-2543.
(21) Forero-Cortés, P. A.; Haydl, A., M. The 25th anniversary of the Buchwald–Hartwig amination:
Development, applications, and outlook. Org. Process Res. Dev. 2019, 23, 8, 1478-1483.
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