Synthesis and biological evaluation of 2,4,5-trisubstituted thiazoles as antituberculosis agents effective against drug-resistant tuberculosis

Article abstract of DOI:10.1016/j.ejmech.2019.05.082

The dormant and resistant form of Mycobacterium tuberculosis presents a challenge in developing new anti-tubercular drugs. Herein, we report the synthesis and evaluation of trisubstituted thiazoles as antituberculosis agents. The SAR study has identified a requirement of hydrophobic substituent at C2, ester functionality at C4, and various groups with hydrogen bond acceptor character at C5 of thiazole scaffold. This has led to the identification of 13h and 13p as lead compounds. These compounds inhibited the dormant Mycobacterium tuberculosis H37Ra strain and M. tuberculosis H37Rv selectively. Importantly, 13h and 13p were non-toxic to CHO cells. The 13p showed activity against multidrug-resistant tuberculosis isolates.

Full text of DOI:10.1016/j.ejmech.2019.05.082

Accepted Manuscript
Synthesis and biological evaluation of 2,4,5-trisubstituted thiazoles as antituberculosis
agents effective against drug-resistant tuberculosis
Uttam B. Karale, Vagolu Siva Krishna, E. Vamshi Krishna, Amit S. Choudhari,
Manjulika Shukla, Vikas R. Gaikwad, B. Mahizhaveni, Sidharth Chopra, Sunil Misra,
Dhiman Sarkar, Dharmarajan Sriram, V.N. Azger Dusthackeer, Haridas B. Rode
PII:
S0223-5234(19)30500-8
DOI:
https://doi.org/10.1016/j.ejmech.2019.05.082
EJMECH 11392
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 12 October 2018
Revised Date: 3 May 2019
Accepted Date: 29 May 2019
Please cite this article as: U.B. Karale, V.S. Krishna, E.V. Krishna, A.S. Choudhari, M. Shukla, V.R.
Gaikwad, B. Mahizhaveni, S. Chopra, S. Misra, D. Sarkar, D. Sriram, V.N.A. Dusthackeer, H.B. Rode,
Synthesis and biological evaluation of 2,4,5-trisubstituted thiazoles as antituberculosis agents effective
against drug-resistant tuberculosis, European Journal of Medicinal Chemistry (2019), doi: https://
doi.org/10.1016/j.ejmech.2019.05.082.
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ACCEPTED MANUSCRIPT
The synthesis and evaluation of trisubstituted thiazoles as antituberculosis agents active against drug-
resistant tuberculosis are reported. The detail structure-activity-relationship study has identified a re-
quirement of hydrophobic substituent at C2, ester functionality at C4, and various groups with hydrogen
bond acceptor character at C5 of thiazole scaffold. This has led to the identification of 13h and 13p as
lead compounds. These compounds inhibited the dormant Mycobacterium tuberculosis H37Ra strain
and M. tuberculosis H37Rv selectively. Importantly, 13h and 13p were non-toxic to CHO cells. The
13p showed activity against multidrug-resistant tuberculosis isolates.

ACCEPTED MANUSCRIPT
Synthesis and biological evaluation of 2,4,5-trisubstituted thiazoles as
antituberculosis agents effective against drug-resistant tuberculosis
Uttam B. Karalea,b, Vagolu Siva Krishnac, E. Vamshi Krishnab,d, Amit S. Choudharie,
Manjulika Shuklaf, Vikas R. Gaikwada,g, B. Mahizhavenih, Sidharth Choprab,f, Sunil Misrab,d
Dhiman Sarkare, Dharmarajan Sriramc, V.N. Azger Dusthackeerh and Haridas B. Rode*a,b
a Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology,
Tarnaka, Hyderabad-500007, India
haridas.rode@iict.res.in
b Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh- 201 002, India
c Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Jawahar Nagar,
Shameerpet mandal, R.R. District, Hyderabad- 500078, India
d Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007,
India
e Department of Biology, CSIR-National Chemical Laboratory, Pashan road, Pune- 411008, India
f Department of Microbiology, CSIR-Central Drug Research Institute, Lucknow-226021, Uttar Pradesh, India
g Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Balanagar,
Hyderabad - 500 037, India
h Department of Bacteriology, National Institute for Research in Tuberculosis, Chennai- 600031, India
KEYWORDS: antituberculosis agents, thiazoles, tuberculosis, dormant tuberculosis, drug resistant tuberculosis
ABSTRACT: The dormant and resistant form of Mycobacterium tuberculosis presents a challenge in
developing new anti-tubercular drugs. Herein, we report the synthesis and evaluation of trisubstituted
thiazoles as antituberculosis agents. The SAR study has identified a requirement of hydrophobic
substituent at C2, ester functionality at C4, and various groups with hydrogen bond acceptor character
at C5 of thiazole scaffold. This has led to the identification of 13h and 13p as lead compounds. These
compounds inhibited the dormant Mycobacterium tuberculosis H37Ra strain and M. tuberculosis
H37Rv selectively. Importantly, 13h and 13p were non-toxic to CHO cells. The 13p showed activity
against multidrug-resistant tuberculosis isolates.
_________________________________________________________________________________
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1. Introduction
Tuberculosis (TB) is one of the major cause of deaths resulting from infectious diseases. According to
the WHO statistics, it was estimated that around 1.4 million deaths occurred due to TB in 2015 and
around 0.4 million more deaths were associated with HIV co-infected TB patients.1 Given the fact that
emergence of multidrug-resistant TB (MDR-TB) and extremely drug-resistant TB (XDR-TB) is on
rise, there is an urgent requirement for the development of new drugs. To develop drugs for TB is a
complicated task as new drug needs to be efficacious and safe in combination with other known TB
drugs. Taken together, it requires intense efforts to develop a new TB drug.
Bedaquiline (1) has been approved for the treatment of MDR-TB and has shown efficacy in XDR-
TB2; while Delamanid (2, figure 1) has been recommended in South Korea, Europe and Japan for the
patients suffering from MDR-TB.3 This has evoked optimism of the scientific community to develop
drugs active against dormant and drug-resistant tuberculosis. Various heterocyclic and other agents
with antituberculosis potential have been reported (figure 1).4-5 These agents include adamantyl
9
ureas6, 1,4-azaindoles (3, MIC range= 0.78-3.12 µM)7, azetidin-2-ones8, benzimidazoles ,
benzothiazoles (4, MIC= 3.12µg/mL)10, calanolides11, pyridine containing diarylethers12, hydrazides
and hydrazones13, quinoline-isoxazole hybrids (5, MIC= 0.2 µM)14, nitrofurans15, oxadiazoles16,
piperidones (6, MIC= 0.78 µg/mL)17, pyrazoles (7, MIC= 0.35 µg/mL)18, pyridines19, pyrroles (8,
MIC= 0.4 µg/mL)20, pyrrolidines21, spectinamides22, sulfonamides23, thiazoles24, thiosemicarbazones25
and triazoles26. The trisubstituted thiazoles effective against HIV-1 reverse transcriptase27 and
benzo[d]thiazole-2-carbanilides as antitubercular agents28 have been reported. In 2014, Chatterji et al.
reported diaryl thiazole containing pyridine (9, MIC= 0.12 µg/mL) with potent antimycobacterial
activity.29 From the SAR (structure-activity relationship) studies, it was clear that the thiazole
containing substituents other than pyridine (10, MIC> 32 µg/mL ) were inactive against M.
tuberculosis H37Rv.29 This was an important observation since pyridine might cause liver toxicity due
to its potential to form reactive metabolites in vivo.30-32 Hence, there is a need to develop thiazole
inhibitors without pyridine substituents. Herein, we report on the development of thiazole-based
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potential antituberculosis agents devoid of pyridine. In addition, these agents showed activity against
dormant M. tuberculosis H37Ra and limited activity against drug resistant TB isolates.
Figure 1: Structures of antituberculosis agents along with MIC value on M. tuberculosis H37Rv
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2. Results and Discussion
2.1. Chemistry: We began our study by synthesizing thiazole derivatives as shown in figure 2.
Thioamides were synthesized from respective amides (11a-11c). The condensation of ethyl
bromopyruvate with thioamides resulted in 2,4-disubstituted thiazoles, 12a-12c. The coupling of 12a-
12c with aryl bromides catalyzed by PdCl2(PPh3)2 in the presence of potassium acetate furnished
trisubstituted thiazole 13a-13r. The esters 13a-13r were hydrolyzed with sodium hydroxide and the
obtained acids were used without purification to couple with amines affording 4-amido 2,5
disubstituted thiazole 14a-14n, 15a-15f, 16a-16f, and 17a-17f .
Figure 2: Synthesis of substituted thiazoles. a) P2S5, diethyl ether, RT, 2 h; b) ethyl bromopyruvate, EtOH,
reflux, 30 min; c) R2 substituted bromides, PdCl2(PPh3)2, KOAc, DMA, 150 °C, 24 h; d) 2N NaOH,
THF:MeOH (3:1); e) R3 substituted amines, EDC.HCl, HOBt, Et3N, DMF, 0°C to RT, overnight.
2.2. Biological activity
2.2.1. Antituberculosis activity
The compounds were screened for their inhibitory potential against M. tuberculosis H37Rv using
MABA assay. The MIC (minimum inhibitory concentration) of these derivatives along with cLogP is
shown in table 1. Rifampicin was used as positive control and demonstrated MIC of 0.2 µg/mL. In
the trisubstituted thiazole series (13a-13r), the MIC varied from 1.8 to >32 µg/mL. Initially,
compounds 13a-13h (isopropyl as R1 substituent) were prepared and screened against M. tuberculosis
H37Rv. Importantly, compounds 13a-13h (except 13b) showed antitubercular activity. Compound
13h showed MIC of 1.8 µg/mL with cLogP of 3.5. Next, we synthesized compounds with cyclohexyl
as R1 substituent (13i-13p) which led to the identification of 13p as potent antitubercular agent with
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MIC of 2.1 µg/mL. This Compound has cLogP of 4.2 and has comparable MIC to that of 13h. In 13i-
13p subseries, except 13j, all other compounds showed antitubercular activity in single digit. When
13a-13h (isopropyl as R1 substituent) compared with 13i-13p (cyclohexyl as R1 substituent), it
clearly showed the preference for cyclohexyl over isopropyl as R1 substituent. Further, compounds
with methyl as R1 substituent (13q, 13r) were less potent as compared to their isopropyl and
cyclohexyl counterparts (13a, 13h and 13i, 13p). It is clear from the structure-activity relationship
(SAR) study that cyclohexyl or isopropyl as R1 substituent and benzonitrile as R2 substituent are
important for their antitubercular activity. From the subseries, 13h and 13p were identified as potent
compounds. Important to note that the position of nitrile on R2 substituent is crucial as 4-benzonitrile
as R2 is more active (13h, MIC= 1.8 µg/mL; 13p, MIC= 2.1 µg/mL) than 3-benzonitrile or 2-
benzonitrile as R2 (13f, 13g and 13n, 13o). Here, the R2 substituent has hydrogen bond acceptor
character which might be important for their activity.
Table 1: Antitubercular activity of thiazole derivatives along with inhibition of dormant M. tuberculosis H37Ra
and cLogP values
O
OEt
R2
N
N
R3
O
R1
R1
S
S
R2
13
14-17
Comp.
no.
Substituents
MIC
(µg/mL)a
%inhibition cLogP
(10µM)b
R1
R2
R3
-
7.9
90.13
3.6
13a
-
>34
NS
3.0
13b
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-
16.3
NS
4.0
4.0
13c
13d
-
4.0
8.1
80.54
-
19.53
3.4
13e
-
-
15.0
15.0
NS
NS
3.6
3.5
13f
13g
-
-
1.8
8.9
82.74
92.01
3.5
4.3
13h
13i
-
19.3
NS
3.7
13j
4.5
4.5
95.97
86.52
4.6
4.8
13k
13l
-
-
-
4.5
93.26
4.1
13m
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-
4.2
91.73
90.34
4.2
4.2
3n
-
4.2
13o
-
-
2.1
90.55
NS
4.2
2.9
13p
13q
13.6
-
14.5
18.7
9.3
20.22
73.25
86.73
89.37
2.9
4.4
4.4
4.4
13r
14a
14b
14c
5.4
>34
>34
NS
NS
2.9
4.0
14d
14e
>34
>34
NS
NS
3.4
4.2
14f
14g
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>34
NS
5.1
4h
>34
>34
NS
NS
4.5
4.6
14i
14j
>34
>34
NS
NS
5.0
5.4
14k
14l
>34
>34
NS
NS
5.0
4.8
14m
14n
4.9
4.9
5.6
90.76
90.90
84.92
4.3
4.5
4.4
15a
15b
15c
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>34
NS
2.9
3.9
3.4
15d
15e
15f
10.6
9.5
82.21
87.14
20.7
10.3
5.9
NS
5.2
5.1
5.1
16a
16b
16c
57.75
71.58
>34
>34
>34
>34
>34
NS
3.6
4.7
4.1
3.8
3.8
16d
16e
16f
NS
NS
73.45
74.01
17a
17b
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>34
67.34
3.8
17c
>34
>34
>34
0.2
NS
NS
NS
NS
2.2
3.4
2.8
-
17d
17e
17f
Rifam
picine
Table 1: (a) Thiazole analogs with their activity against replicating M. tuberculosis H37Rv. (b) percent
inhibition of dormant M. tuberculosis H37Ra. (c) cLogP is calculated using SwissADME. NS: Not screened.
Upon having deciphered the importance of R1 and R2 substituents, we decided to prepare analogs with
different R3 substituents. Accordingly, 32 analogs were prepared and screened against M. tuberculosis
H37Rv ( Table 1). Compound 14b, 14c, 15a, 15b, 15c, 15f and 16c showed MIC of less than 10
µg/mL while rest other molecules showed weaker inhibition or were inactive. This indicates that the
amide substitution as R3 is not favorable when compared to ester functionality at this position
(compare series 14-17 vs 13a-13r). The SAR along with cLogP analysis (figure 3) identified
compound 13d, 13h, 13n, 13o and 13p potent inhibitors with MIC ≤ 4.2 µg/mL and cLogP lower than
5. LogP is one of the important parameter in Lipinski's rule of five33-34 which determines the drug-
likeness of compounds. Further, the compounds were screened for their ability to inhibit dormant M.
tuberculosis H37Ra (Table 1). Compounds 13a, 13i, 13k, 13m-13p, 15a, and 15b showed more than
90% inhibition of dormant M. tuberculosis H37Ra at 10 µM concentration.
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O
O
O
N
S
N
S
EtO
EtO
N
N
S
EtO
CN
NC
13n
13d
13h
O
O
N
N
S
EtO
EtO
S
NC
13o
13p
CN
Figure 3: Correlation of antitubercular activity of compounds with cLogP. The MIC >34 µg/mL is taken as 50
µg/mL for simplicity in graphical presentation. Structures of compounds with MIC≤4.2 µg/mL against M.
tuberculosis H37Rv with cLogP <5 are shown.
2.2.2. Cytotoxicity
The compounds showing MIC ≤ 4.2 µg/mL against M. tuberculosis H37Rv were further screened for
cytotoxicity against CHO-KI cells. The cytotoxicity data for compounds is shown in table 2. All the
compounds were non-toxic to CHO cells. Importantly, compound 13h and 13P showed selectivity
index of 22 and 35 respectively. Of note, compounds presented in table 2 did not show any inhibition
of B16-F10 and MCF7 cell lines at 10 µM concentration (data not shown).
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Table 2: Effect of thiazole analogous against CHO-K1 (Chinese hamster ovary cells)
Comp. no.
IC50 (µg/mL)
CHO-KI
>50
SI Index
(IC50/MIC)
>12.5
22.4
13d
40.47
13h
>50
>11.9
>11.9
35.8
13n
>50
13o
75.23
13p
13.10
-
Mitomycin C
2.2.3. Effect on ESKAPE pathogen and other bacteria
The compounds showing MIC ≤ 4.2 µg/mL against M. tuberculosis H37Rv were screened against a
panel of bacteria consisting of ESKAPE pathogens namely Escherichia coli, Klebsiella pneumoniae,
Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus. The results are
presented in supporting information. None of the derivatives showed any inhibition except
Staphylococcus aureus. Staphylococcus aureus was weakly sensitive to 13n, 13o and 13p with MIC
of 50 µM . Furthermore, these compounds were tested against nontuberculous mycobacteria namely
Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus (data not shown).
None of the thiazole derivatives showed inhibition indicating their selective inhibition of M.
tuberculosis H37Rv.
2.2.4. Effect against MDR-TB isolates
The compound 13p was profiled against a panel of drug-resistant TB isolates (Table 3). This
compound showed MIC of 8 µg/mL against clinical isolate 1, 2, 5 and 6. Important to note that the
isolate 4 is resistant to four TB drugs, i.e. isoniazid, streptomycin, ethionamide and ethambutol.
Compound 13P showed MIC of 16, 6 and 16 µg/mL against MDR-TB isolate 3,4 and 7 respectively.
Thus , compound 13P showed limited activity against clinical isolate 1 to 7 whereas it was ineffective
against pre-extensively drug resistant (Pre-XDR)35 isolate 8. Compound 13p was non toxic to CHO
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cells at 8 µg/mL and hence has possibility for further development to render it more efficacious
against MDR-TB.
Table 3: Activity of 13p against drug resistant tuberculosis isolates
Clinical
isolate
Description
MIC
(µg/mL)
Isolate 1
Resistant to isoniazid, streptomycin, ethionamide and
ethambutol
8
Isolate 2
Isolate 3
Isolate 4
Isolate 5
Isolate 6
Isolate 7
Resistant to isoniazid and ethionamide
Resistant to isoniazid, streptomycin and rifampicin
Resistant to isoniazid and rifampicin
8
16
4
Resistant to isoniazid and ethionamide
8
Resistant to isoniazd, streptomycin and ethionamide
8
Resistant to isoniazid, streptomycin, ethambutol,
rifampicin, ethionamide
16
Isolate 8
Resistant to isoniazid, streptomycin, ethionamide,
ofloxacin, ethambutol and rifampicin
>32
3. Molecular Docking study
Finally, in order to understand the possible binding mode of these thiazole analogs, we carried out
docking of 13p and 13d in the active site of CTP (cytidine triphosphate) synthase PyrG (Maestro 9.8,
Schrodinger, New York, U.S.A). Recently PyrG has shown to be a relevant target in tuberculosis drug
discovery.36 Further, Chiarelli et al.37 showed that the thiazole-based GSK compounds inhibit PyrG.
Figure 4 shows interaction of 13p and 13d with amino acid residues of the ATP binding site of PyrG.
The thiazole-nitrogen of 13p interacts with magnesium ion whereas ester functionality is involved in
hydrogen bond interactions with protonated Lys24 and Lys46 residues of PyrG. In the case of 13d,
the interaction between protonated Lys46 of PyrG with carbonyl of ester is preserved, while Gly155
interacts with ester side chain. Interesting to note that the quinoline nitrogen of 13d interacts with the
magnesium ion. Further, we docked compounds in the active site of PyrG and determined the docking
score. No correlation was observed between the docking score and MIC of compounds against M.
tuberculosis H37Rv (supporting information).
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A)
B)
C)
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D)
Figure 4: Docking of the thiazole derivatives in the active site of CTP synthase PyrG. A) The three dimensional
representation of interaction of 13p with CTP synthase PyrG , docking (XP G) score is -5.61 kcal/mol; B) The
two dimensional interaction map of 13P with CTP synthase PyrG; C) The three dimensional representation of
interaction of 13d with CTP synthase PyrG , docking (XP G) score is -6.04 kcal/mol; D) The two dimensional
interaction map of 13d with CTP synthase PyrG.
4. Conclusion
In summary, the thiazole derivatives with antitubercular properties on drug sensitive and dormant
mycobacterial strains are reported. The SAR study identified a requirement of hydrophobic
substituent at C2, ester functionality at C4, and various groups with hydrogen bond acceptor character
at C5 of thiazole scaffold. These derivatives selectively inhibited M. tuberculosis H37Rv while
docking study revealed key interactions of thiazole derivative 13p with Lys24 and Lys46 residues of
CTP synthase PyrG. Importantly, 13P was active against multidrug-resistant tuberculosis isolates.
5. Experimental
5.1. General methods for the synthesis of compounds
Synthesis of 2a-2c thiazole
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To a solution of phosphorus pentasulfide (P2S5) (4.58 mmol) in ether (8ml) was added isobutylamide
11a (1gm, 11 mmol) and the reaction mixture was stirred for 2h at room temperature. The reaction
mixture was diluted with brine and extracted with ether. The organic layer was dried over Na2SO4 and
evaporated to give crude thioamide. The mixture of crude thioamide and ethyl α-bromopyruvate
(11.42 mmol) in EtOH (10ml) was stirred at reflux temperature for 30 min. The solvent was
evaporated under vaccum, diluted with EtOAc and washed with 7% aqueous NaHCO3 (3×30 mL), the
organic layer was dried over Na2SO4 and evaporated to get crude product, which was purified by
column chromatography (n-hexane/EtOAc) to afford 12a.
In an analogous way 12b, 12c were synthesized.
Synthesis of 13a-13r
In round bottom flask, added 12a (100 mg, 0.5mmol) followed by 4-bromo-1,2-
(methylenedioxy)benzene (0.45 mmol), PdCl2(PPh3)2 (5mol%) and KOAc (0.5mmol) sequentially in
dry DMA (10ml). The reaction mixture was stirred at 150 ºC for 18h. The reaction mixture was
diluted with saturated NaHCO3 and extracted with EtOAc. The organic layer dried over Na2SO4,
filtered and evaporated to give crude product which was finally purified by column chromatography
to afford 13a.
In an analogous way 13b-13r were synthesized.
Synthesis of 14a-17f
In round bottom flask, 200 mg of 13a was dissolved in 8 ml of THF:MeOH (3:1), the solution of 2
equivalent aq. NaOH (1.5ml) was added slowly at 0 ºC and reaction mixture allowed to stir for 3h at
room temperature. The solvent was evaporated under vaccum and the residue was diluted with water
(2ml) and cooled to 0 ºC. The reaction mixture was acidified with 4M HCl. Resulting Solid was
filtered and dried to afford acid which was used in the next step without purification.
To the solution of acid in DMF (7ml), were added EDC.HCl (1 mmol) and HOBt (1 mmol)
respectively at 0 ºC. The solution was stirred for 30 min followed by addition of (S)-1-phenylethan-1-
amine (0.8 mmol) and NEt3 (1.33 mmol). The reaction mixture was stirred for 1h at 0 ºC and then for
12 h at room temperature. The reaction mixture was quenched by saturated NaHCO3 and then
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extracted with EtOAc. The organic layer was dried with Na2SO4 and concentrated under reduced
pressure. The crude residue was purified by column chromatography to obtain pure 15a.
In an analogous way, 14-17 were synthesized.
5.2 Analytical data of the compounds
Ethyl 2-isopropylthiazole-4-carboxylate (12a)
The compound is synthesized according to the literature procedure.38 Yellow liquid (1.26 gm, 61%).
1H NMR (500 MHz, CDCl3) δ 8.05 (s, 1H), 4.41 (q, J = 7.19, 2H), 3.42 (sept, J = 6.8 Hz, 1H), 1.41
13
(d, J = 6.8 Hz, 6H), 1.39 (t, J =7.1,3H); C NMR (125 MHz, CDCl3) δ 178.5, 161.1, 146.2, 126.1,
60.9, 33.1, 22.9 (X2), 14.0.
Ethyl 2-cyclohexylthiazole-4-carboxylate (12b)
The compound is synthesized according to the reported literature.39 Yellow liquid (1.62 gm, 86%). 1H
NMR (500 MHz, CDCl3) δ 8.01 (s, 1H), 4.37 (q, J = 7.1 Hz, 2H), 3.06 (tt, J = 11.7, 3.6 Hz, 1H), 2.12
(dd, J = 13.1, 1.8 Hz, 2H), 1.83 – 1.78 (m, 2H), 1.72 – 1.68 (m, 1H), 1.46 (m, 2H), 1.40 – 1.31 (m,
2H), 1.35 (t, J = 7.1 Hz, 3H), 1.28 – 1.21 (m, 1H); 13C NMR (75 MHz, CDCl3) δ 178.1, 161.4, 146.2,
126.3, 61.2, 42.6, 33.7 (X2), 25.9 (X2), 25.5, 14.3.
Ethyl 2-cyclohexylthiazole-4-carboxylate (12c)
White solid (1.5 gm, 53%). 1H NMR (500 MHz, CDCl3) δ ppm 8.01 (s, 1H), 4.39 (q, J = 7.1 Hz, 2H),
2.74 (s, 3H), 1.37 (t, J = 7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 166.8, 161.4, 146.9, 127.3, 61.4,
19.4, 14.4; HRMS (ESI-MS):Calc. for C7H10NO2S [(M+H)+]: 172.0432, Found: 172.0426.
Ethyl 5-(benzo[d][1,3]dioxol-5-yl)-2-isopropylthiazole-4-carboxylate (13a)
1
White solid (70 mg, 43%). H NMR (400 MHz, CDCl3) δ ppm 6.97 – 6.91 (m, 2H), 6.82 (d, J = 7.9
Hz, 1H), 6.00 (s, 2H), 4.30 (q, J = 7.1 Hz, 2H), 3.38 (sept, J = 6.9 Hz, 1H), 1.41 (d, J = 6.9 Hz, 6H),
1.27 (t, J = 7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 176.1, 162.4, 148.4, 147.4, 145.1, 139.6,
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ACCEPTED MANUSCRIPT
124.4, 124.0, 110.5, 108.1, 101.5, 61.3, 33.7, 23.4 (X2), 14.2; HRMS (ESI-MS):Calc. for C16H18NO4S
[(M+H)+]: 320.0957, Found: 320.0965.
Ethyl
(13b)
2-isopropyl-5-(3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)thiazole-4-carboxylate
1
Brown solid (60 mg, 37%). H NMR (400 MHz, CDCl3) δ ppm 8.76 (s, 1H), 7.08 (dd, J = 8.3, 2.0
Hz, 1H), 7.09 – 6.96 (m, 2H), 4.65 (s, 2H), 4.30 (q, J = 7.1 Hz, 2H), 3.38 (sept, J = 6.9 Hz, 1H), 1.42
(d, J = 6.9 Hz, 6H), 1.27 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 176.6, 165.7 (X2), 162.4,
144.3, 139.8, 126.2, 125.9, 125.4, 117.7, 116.6, 67.3, 61.5, 33.8, 23.4 (X2), 14.3; HRMS (ESI-
MS):Calc. for C17H19N2O4S [(M+H)+]: 347.1066, Found: 347.1065.
Ethyl 2-isopropyl-5-(isoquinolin-5-yl)thiazole-4-carboxylate (13c)
1
Yellow solid (83 mg, 50%). H NMR (400 MHz, CDCl3) δ ppm 9.30 (s, 1H), 8.50 (d, J = 6.0 Hz,
1H), 8.04 (d, J = 8.1 Hz, 1H), 7.70 (dd, J = 7.1, 1.3 Hz, 1H), 7.67 – 7.61 (m, 1H), 7.43 (d, J = 6.0 Hz,
1H), 4.00 (q, J = 7.1 Hz, 2H), 3.48 (sept, J = 6.9 Hz, 1H), 1.48 (d, J = 6.9 Hz, 6H), 0.76 (t, J = 7.1 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 178.1, 161.5, 152.8, 143.9, 142.8, 140.7, 135.1, 132.3, 128.9,
128.4, 128.3, 126.4, 118.2, 61.1, 33.8, 23.4 (X2), 13.6; HRMS (ESI-MS):Calc. for C18H19N2O2S
[(M+H)+]: 327.1178, Found: 327.1167.
Ethyl 2-isopropyl-5-(quinolin-3-yl)thiazole-4-carboxylate (13d)
1
Yellow semisolid (60 mg, 36%). H NMR (400 MHz, CDCl3) δ ppm 8.94 (d, J = 2.2 Hz, 1H), 8.22
(d, J = 2.0 Hz, 1H), 8.10 (d, J = 8.4 Hz, 1H), 7.80 (d, J = 8.2 Hz, 1H), 7.72 (ddd, J = 8.4, 6.9, 1.4 Hz,
1H), 7.55 (ddd, J = 8.1, 7.0, 1.1 Hz, 1H), 4.24 (q, J = 7.1 Hz, 2H), 3.41 (sept, J = 6.9 Hz, 1H), 1.43 (d,
13
J = 6.9 Hz, 6H), 1.13 (t, J = 7.1 Hz, 3H); C NMR (125 MHz, CDCl3) δ 177.5, 161.9, 150.8, 147.6,
141.3, 140.9, 136.6, 130.3, 129.3, 128.0, 127.3, 127.0, 124.5, 61.4, 33.7, 23.3 (X2), 14.1; HRMS
(ESI-MS):Calc. for C18H19N2O2S [(M+H)+]: 327.1167, Found: 327.0978.
Ethyl 2-isopropyl-5-(quinoxalin-6-yl)thiazole-4-carboxylate (13e)
18

ACCEPTED MANUSCRIPT
1
Yellow solid (70 mg, 42%). H NMR (400 MHz, CDCl3) δ ppm 8.88 (s, 2H), 8.21 (d, J = 1.9 Hz,
1H), 8.14 (d, J = 8.7 Hz, 1H), 7.89 (dd, J = 8.7, 2.0 Hz, 1H), 4.30 (q, J = 7.1 Hz, 2H), 3.45 (sept, J =
6.9 Hz, 1H), 1.47 (d, J = 6.9 Hz, 6H), 1.20 (t, J = 7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 177.6,
162.1, 145.8, 145.7, 143.4, 143.0, 142.5, 140.7, 133.2, 132.2, 130.7, 129.2, 61.6, 33.9, 23.4 (X2),
14.2; HRMS (ESI-MS):Calc. for C17H18N3O2S [(M+H)+]: 328.1120, Found: 328.1121.
Ethyl 5-(2-cyanophenyl)-2-isopropylthiazole-4-carboxylate (13f)
Yellow solid (50 mg, 33%). 1H NMR (400 MHz, CDCl3) δ ppm 7.74 (dd, J = 7.7, 0.9 Hz, 1H), 7.62
(td, J = 7.7, 1.4 Hz, 1H), 7.51 (td, J = 7.7, 1.3 Hz, 1H), 7.46 (dd, J = 7.7, 0.8 Hz, 1H), 4.25 (q, J = 7.1
Hz, 2H), 3.43 (sept, J = 6.9 Hz, 1H), 1.44 (d, J = 6.9 Hz, 6H), 1.16 (t, J = 7.1 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 178.2, 161.5, 142.4, 139.8, 135.2, 132.9, 132.3, 131.2, 129.2, 117.4, 113.9, 61.5, 33.8,
23.3 (X2), 14.0; HRMS (ESI-MS):Calc. for C16H17N2O2S [(M+H)+]: 301.1011, Found: 301.1034.
Ethyl 5-(3-cyanophenyl)-2-isopropylthiazole-4-carboxylate (13g)
White solid (45 mg, 30%). 1H NMR (400 MHz, CDCl3) δ ppm 7.77 (t, J = 1.4 Hz, 1H), 7.73 – 7.66
(m, 2H), 7.52 (t, J = 8.0 Hz, 1H), 4.29 (q, J = 7.1 Hz, 2H), 3.42 (sept, J = 6.9 Hz, 1H), 1.44 (d, J = 6.9
13
Hz, 6H), 1.23 (t, J = 7.1 Hz, 3H); C NMR (100 MHz, CDCl3) δ 177.6, 161.9, 142.2, 140.8, 134.4,
133.5, 132.6, 132.4 129.0, 118.3, 112.6, 61.6, 33.8, 23.4 (X2), 14.2; HRMS (ESI-MS):Calc. for
C16H17N2O2S [(M+H)+]: 301.1011, Found: 301.1019.
Ethyl 5-(4-cyanophenyl)-2-isopropylthiazole-4-carboxylate (13h)
White solid (60 mg, 40%). 1H NMR (500 MHz, CDCl3) δ ppm 7.69 (d, J = 8.5 Hz, 2H), 7.58 (d, J =
8.6 Hz, 2H), 4.29 (q, J = 7.1 Hz, 2H), 3.42 (sept, J = 6.9 Hz, 1H), 1.44 (d, J = 6.9 Hz, 6H), 1.23 (t, J =
7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3) δ 177.8, 161.9, 142.6, 140.8, 135.9, 131.8 (X2), 130.8 (X2),
118.4, 112.6, 61.6, 33.7, 23.3 (X2), 14.1; HRMS (ESI-MS):Calc. for C16H17N2O2S [(M+H)+]:
301.1011, Found: 301.1014.
Ethyl 5-(benzo[d][1,3]dioxol-5-yl)-2-cyclohexylthiazole-4-carboxylate (13i)
19

ACCEPTED MANUSCRIPT
1
White solid (40 mg, 26%). H NMR (400 MHz, CDCl3) δ ppm 6.97 – 6.91 (m, 2H), 6.82 (d, J = 7.9
Hz, 1H), 6.00 (s, 2H), 4.30 (q, J = 7.1 Hz, 2H), 3.11 – 3.00 (m, 1H), 2.17 (d, J = 12.1 Hz, 2H), 1.89 –
1.81 (m, 2H), 1.80 – 1.70 (m, 1H), 1.55 – 1.32 (m, 5H), 1.26 (t, J = 7.1 Hz, 3H); 13C NMR (75 MHz,
CDCl3) δ 175.0, 162.3, 148.2, 147.3, 145.0, 139.3, 124.3, 123.9, 110.4, 107.9, 101.4, 61.1, 42.8, 33.9
(X2), 26.0 (X2), 25.6, 14.2; HRMS (ESI-MS):Calc. for C19H22NO4S [(M+H)+]: 360.1270, Found:
360.1288.
Ethyl
(13j)
2-cyclohexyl-5-(3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)thiazole-4-carboxylate
1
Yellow solid (60 mg, 37%). H NMR (500 MHz, CDCl3) δ ppm 8.97 (bs, 1H), 7.07 (dd, J = 8.4, 1.9
Hz, 1H), 7.00 – 6.96 (m, 2H), 4.65 (s, 2H), 4.30 (q, J = 7.1 Hz, 2H), 3.07 (tt, J = 11.6, 7.02, 3.5 Hz,
1H), 2.17 (d, J = 12.1 Hz, 2H), 1.87 – 1.83 (m, 2H), 1.77 – 1.73 (m, 1H), 1.54 – 1.35 (m, 5H), 1.27 (t,
J = 7.1 Hz, 3H); 13C NMR (125MHz, CDCl3) δ 175.6, 165.8, 162.4, 144.3, 144.2, 139.7, 126.2,
125.9, 125.5, 117.7, 116.6, 67.3, 61.4, 43.0, 34.0 (X2), 26.1 (X2), 25.8, 14.3; HRMS (ESI-MS):Calc.
for C20H23N2O4S [(M+H)+]: 387.1379, Found: 387.1385.
Ethyl 2-cyclohexyl-5-(isoquinolin-5-yl)thiazole-4-carboxylate (13k)
White solid (65 mg, 42%). 1H NMR (400 MHz, CDCl3) δ ppm 9.30 (s, 1H), 8.49 (d, J = 5.6 Hz, 1H),
8.04 (dt, J = 8.06, 1.0 Hz, 1H), 7.69 (dd, J = 7.1, 1.4 Hz, 1H), 7.67 – 7.61 (m, 1H), 7.43 (d, J = 5.9
Hz, 1H), 4.01 (q, J = 7.1 Hz, 2H), 3.15 (tt, J = 11.7, 3.6 Hz, 1H), 2.25 (dd, J = 13.0, 2.1 Hz, 2H), 1.92
– 1.85 (m, 2H), 1.81 – 1.73 (m, 1H), 1.56 (qd, J = 12.3, 3.1 Hz, 2H), 1.43 (qt, J = 12.3, 3.1 Hz, 2H),
1.36 – 1.23 (m, 1H), 0.78 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 177.0, 161.5, 152.8,
143.8, 142.7, 140.5, 135.0, 132.2, 128.9, 128.3, 126.4, 118.1, 61.0, 43.0, 33.9 (X2), 26.1 (X2), 25.7,
13.6; HRMS (ESI-MS):Calc. for C21H23N2O2S [(M+H)+]: 367.1480, Found: 367.1507.
Ethyl 2-cyclohexyl-5-(quinolin-3-yl)thiazole-4-carboxylate (13l)
White solid (58 mg, 38%). 1H NMR (500 MHz, CDCl3) δ ppm 8.97 (d, J = 2.2 Hz, 1H), 8.26 (d, J =
2.0 Hz, 1H), 8.14 (d, J = 8.4 Hz, 1H), 7.85 (d, J = 7.8 Hz, 1H), 7.80 – 7.73 (m, 1H), 7.63 – 7.56 (m,
20

ACCEPTED MANUSCRIPT
1H), 4.28 (q, J = 7.1 Hz, 2H), 3.13 (tt, J = 11.7, 3.5 Hz, 1H), 2.22 (dd, J = 13.1, 1.8 Hz, 2H), 1.93 –
1.83 (m, 2H), 1.80 – 1.74 (m, 1H), 1.54 (qd, J = 12.3, 3.1 Hz, 2H), 1.43 (qt, J = 12.3, 3.1 Hz, 2H),
1.35 – 1.27 (m, 1H), 1.17 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 176.7, 162.1, 151.0,
147.7, 141.3, 141.0, 136.7, 130.5, 129.5, 128.2, 127.4, 127.1, 124.7, 61.6, 43.1, 34.0 (X2), 26.1 (X2),
25.8, 14.2; HRMS (ESI-MS):Calc. for C21H23N2O2S [(M+H)+]: 367.1480, Found: 367.1267.
Ethyl 2-cyclohexyl-5-(quinoxalin-6-yl)thiazole-4-carboxylate (13m)
Yellow solid (50mg, 32%). 1H NMR (500 MHz, CDCl3) δ ppm 8.88 (s, 2H), 8.20 (d, J = 1.8 Hz, 1H),
8.13 (d, J = 8.7 Hz, 1H), 7.89 (dd, J = 8.7, 1.9 Hz, 1H), 4.30 (q, J = 7.1 Hz, 2H), 3.13 (tt, J = 11.7, 3.5
Hz, 1H), 2.23 (d, J = 11.5 Hz, 2H), 1.93 – 1.87 (m, 2H), 1.80 – 1.75 (m, 1H), 1.54 (qd, J = 12.4, 3.0
Hz, 2H), 1.45 (qt, J = 12.5, 3.0 Hz, 2H), 1.35 – 1.30 (m, 1H), 1.20 (t, J = 7.1 Hz, 3H); 13C NMR (100
MHz, CDCl3) δ 176.7, 162.2, 145.8, 145.7, 143.3, 143.0, 142.6, 140.6, 133.2, 132.2, 130.6, 129.1,
61.6, 43.1, 34.0 (X2), 26.1 (X2), 25.8, 14.2; HRMS (ESI-MS):Calc. for C20H22N3O2S
[(M+H)+]:368.1433, Found: 368.1440.
Ethyl 5-(2-cyanophenyl)-2-cyclohexylthiazole-4-carboxylate (13n)
Yellow solid (70 mg, 50%). 1H NMR (500 MHz, CDCl3) δ ppm 7.75 (dd, J = 7.7, 1.0 Hz, 1H), 7.63
(td, J = 7.7, 1.3 Hz, 1H), 7.51 (td, J = 7.7, 1.3 Hz, 1H), 7.47 (d, J = 7.8 Hz, 1H), 4.26 (q, J = 7.1 Hz,
2H), 3.12 (tt, J = 11.7, 3.5 Hz, 1H), 2.22 (dd, J = 13.1, 2.0 Hz, 2H), 1.87 (dt, J = 13.2, 3.3 Hz, 2H),
1.80 – 1.72 (m, 1H), 1.52 (qd, J = 12.3, 3.2 Hz, 2H), 1.42 (qt, J = 12.5, 3.1 Hz, 2H), 1.34 – 1.26 (m,
1H), 1.18 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 177.3, 161.6, 142.3, 139.7, 135.3, 133.0,
132.3, 131.2, 129.2, 117.4, 114.0, 61.5, 43.0, 33.9 (X2), 26.0 (X2), 25.7, 14.1; HRMS (ESI-MS):Calc.
for C19H21N2O2S [(M+H)+]: 341.1324, Found: 341.1343.
Ethyl 5-(3-cyanophenyl)-2-cyclohexylthiazole-4-carboxylate (13o)
1
White solid (60 mg, 42%). H NMR (400 MHz, CDCl3) δ ppm 7.76 (t, J = 1.4 Hz, 1H), 7.69 (tt, J =
7.6, 1.2 Hz, 2H), 7.52 (t, J = 7.9 Hz, 1H), 4.29 (q, J = 7.1 Hz, 2H), 3.10 (tt, J = 11.6, 3.5 Hz, 1H), 2.30
– 2.13 (m, 2H), 1.86 (dt, J = 13.2, 3.3 Hz, 2H), 1.80 – 1.71 (m, 1H), 1.56 – 1.35 (m, 4H), 1.34 – 1.26
21

ACCEPTED MANUSCRIPT
13
(m, 1H), 1.23 (t, J = 7.1 Hz, 3H); C NMR (100 MHz, CDCl3) δ 176.6, 161.9, 142.1, 140.7, 134.4,
133.5, 132.6, 132.3, 129.0, 118.3, 112.6, 61.5, 43.0, 34.0 (X2), 26.1 (X2), 25.7, 14.2; HRMS (ESI-
MS):Calc. for C19H21N2O2S [(M+H)+]: 341.1324, Found: 341.1329.
Ethyl 5-(4-cyanophenyl)-2-cyclohexylthiazole-4-carboxylate (13p)
White solid (70 mg, 50%). 1H NMR (500 MHz, CDCl3) δ ppm 7.69 (d, J = 8.5 Hz, 2H), 7.58 (d, J =
8.6 Hz, 2H), 4.29 (q, J = 7.1 Hz, 2H), 3.10 (tt, J = 11.7, 3.5 Hz, 1H), 2.18 (dd, J = 10.5, 8.6 Hz, 2H),
1.87 (dt, J = 13.1, 3.3 Hz, 2H), 1.80 – 1.72 (m, 1H), 1.51 (qd, J = 12.3, 3.2 Hz, 2H), 1.41 (qt, J = 12.5,
3.1 Hz, 2H), 1.34 – 1.26 (m, 1H), 1.24 (t, J = 7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 176.7,
161.9, 142.5, 140.6, 135.9, 131.8 (X2), 130.8 (X2), 118.4, 112.6, 61.5, 43.0, 33.9 (X2), 26.0 (X2),
25.7, 14.2; HRMS (ESI-MS):Calc. for C19H21N2O2S [(M+H)+]: 341.1324, Found: 341.1351.
Ethyl 5-(benzo[d][1,3]dioxol-5-yl)-2-methylthiazole-4-carboxylate (13q)
White solid (70 mg, 41%). 1H NMR (500 MHz, CDCl3) δ ppm 6.96 – 6.91 (m, 2H), 6.82 (d, J = 8.0
Hz, 1H), 6.00 (s, 2H), 4.31 (q, J = 7.1 Hz, 2H), 2.71 (s, 3H), 1.28 (t, J = 7.1 Hz, 3H); 13C NMR (125
MHz, CDCl3) δ 164.0, 162.0, 148.4, 147.4, 146.3, 139.7, 124.0, 123.9, 110.5, 108.1, 101.5, 61.3, 19.3,
14.2; HRMS (ESI-MS):Calc. for C14H14NO4S [(M+H)+]: 292.0644, Found: 292.0649.
Ethyl 5-(4-cyanophenyl)-2-methylthiazole-4-carboxylate (13r)
White solid (100 mg, 43%). 1H NMR (500 MHz, CDCl3) δ ppm 7.70 (d, J = 8.3 Hz, 2H), 7.58 (d, J =
13
8.4 Hz, 2H), 4.31 (q, J = 7.1 Hz, 2H), 2.78 (s, 3H), 1.26 (t, J = 7.1 Hz, 3H); C NMR (125 MHz,
CDCl3) δ 165.7, 161.6, 143.7, 140.9, 135.5, 131.8 (X2), 130.8 (X2), 118.4, 112.7, 61.6, 19.4, 14.1;
HRMS (ESI-MS):Calc. for C14H13N2O2S [(M+H)+]: 273.0698, Found: 273.0700.
(S)-5-(4-cyanophenyl)-2-isopropyl-N-(1-phenylethyl)thiazole-4-carboxamide (14a)
White solid (140 mg, 56%). 1H NMR (500 MHz, CDCl3) δ ppm 7.79 (d, J = 8.5 Hz, 1H), 7.70 (d, J =
8.6 Hz, 2H), 7.65 (d, J = 8.6 Hz, 2H), 7.39 – 7.32 (m, 4H), 7.29 – 7.26 (m, 1H), 5.22 (qn, J =7.0 Hz,
1H), 3.29 (sept, J = 6.9 Hz, 1H), 1.58 (d, J = 6.9 Hz, 3H), 1.44 (d, J = 1.6 Hz, 3H), 1.42 (d, J = 1.6
22

ACCEPTED MANUSCRIPT
13
Hz, 3H); C NMR (100 MHz, CDCl3) δ 176.4, 160.5, 143.3, 142.0, 139.8, 135.8, 131.7 (X2), 131.1
(X2), 128.8 (X2), 127.4, 126.3 (X2), 118.7, 112.3, 48.6, 33.4, 23.1 (X2), 22.2; HRMS (ESI-MS):Calc.
for C22H22N3OS [(M+H)+]: 376.1484, Found: 376.1490.
(R)-5-(4-cyanophenyl)-2-isopropyl-N-(1-phenylethyl)thiazole-4-carboxamide (14b)
White solid (125 mg, 50%). 1H NMR (500 MHz, CDCl3) δ ppm 7.80 (d, J = 8.3 Hz, 1H), 7.71 – 7.68
(m, 2H), 7.67 – 7.63 (m, 2H), 7.40 – 7.32 (m, 4H), 7.29 – 7.25 (m, 1H), 5.22 (qn, J =7.0 Hz, 1H), 3.29
(sept, J = 6.9 Hz, 1H), 1.58 (d, J = 6.9 Hz, 3H), 1.44 (d, J = 1.6 Hz, 3H), 1.42 (d, J = 1.6 Hz, 3H); 13C
NMR (125 MHz, CDCl3) δ 176.4, 160.5, 143.3, 142.0, 139.7, 135.8, 131.6 (X2), 131.1 (X2), 128.8
(X2), 127.4, 126.3 (X2), 118.7, 112.3, 48.6, 33.4, 23.1 (X2), 22.2; HRMS (ESI-MS):Calc. for
C22H22N3OS [(M+H)+]: 376.1494, Found: 376.1492.
5-(4-cyanophenyl)-N-(3,4-dimethoxyphenethyl)-2-isopropylthiazole-4-carboxamide (14c)
Yellow solid (80 mg, 55%). 1H NMR (500 MHz, CDCl3) δ ppm 7.71 – 7.65 (m, 4H), 7.64 – 7.61 (m,
1H), 6.81 (d, J = 8.1 Hz, 1H), 6.79 – 6.74 (m, 2H), 3.86 (s, 3H), 3.84 (s, 3H), 3.59 (q, J = 7.0 Hz, 2H),
13
3.24 (sept, J = 6.9 Hz, 1H), 2.83 (t, J = 7.2 Hz, 2H), 1.41 (d, J = 6.9 Hz, 6H); C NMR (75 MHz,
CDCl3) δ 176.2, 161.4, 149.1, 147.8, 142.1, 139.6, 135.8, 131.7 (X2), 131.6, 131.1 (X2), 120.8, 118.7,
112.3, 112.1, 111.5, 56.0, 55.9, 40.8, 35.6, 33.4, 23.0 (X2); HRMS (ESI-MS):Calc. for C24H26N3O3S
[(M+H)+]: 436.1695, Found: 436.1700.
4-(2-isopropyl-4-(morpholine-4-carbonyl)thiazol-5-yl)benzonitrile (14d)
White solid (55 mg, 24%). 1H NMR (500 MHz, CDCl3) δ ppm 7.68 (d, J = 8.6 Hz, 2H), 7.62 (d, J =
8.6 Hz, 2H), 3.78 – 3.66 (m, 4H), 3.44 (t, J = 4.6 Hz, 2H), 3.32 (sept, J = 6.9 Hz, 1H), 3.24 (t, J = 4.9
13
Hz, 2H), 1.43 (d, J = 6.9 Hz, 6H); C NMR (75 MHz, CDCl3) δ 178.6, 164.21, 144.8, 135.2, 133.5,
132.8 (X2), 129.0 (X2), 118.3, 112.3, 66.8, 66.7, 47.3, 42.5, 33.6, 23.1 (X2); HRMS (ESI-MS):Calc.
for C18H20N3O2S [(M+H)+]: 342.1276, Found: 342.1283.
N-(benzo[d][1,3]dioxol-5-ylmethyl)-5-(4-cyanophenyl)-2-isopropylthiazole-4-carboxamide (14e)
23

ACCEPTED MANUSCRIPT
White solid (100 mg, 37%). 1H NMR (400 MHz, CDCl3) δ ppm 7.80 (t, J = 5.8 Hz, 1H), 7.72 (d, J =
8.6 Hz, 2H), 7.67 (d, J = 8.6 Hz, 2H), 6.83 (d, J = 1.5 Hz, 1H), 6.82 – 6.74 (m, 2H), 5.94 (s, 2H),
13
4.47 (d, J = 6.1 Hz, 2H), 3.26 (sept, J = 6.9 Hz, 1H), 1.41 (d, J = 6.9 Hz, 6H); C NMR (100 MHz,
CDCl3) δ 176.4, 161.2, 147.9, 147.0, 141.9, 139.9, 135.7, 132.1, 131.6 (X2), 131.1 (X2), 121.1, 118.7,
112.8, 108.5, 108.3, 101.1, 43.0, 33.4, 23.0 (X2); HRMS (ESI-MS):Calc. for C22H20N3O3S [(M+H)+]:
406.1225, Found: 406.1229.
5-(4-cyanophenyl)-2-isopropyl-N-(pyridin-3-ylmethyl)thiazole-4-carboxamide (14f)
1
White solid (110 mg, 41%). H NMR (500 MHz, CDCl3) δ ppm 8.60 (s, 1H), 8.53 (d, J = 4.3 Hz,
1H), 7.93 (t, J = 5.8 Hz, 1H), 7.71 (d, J = 8.5 Hz, 2H), 7. 69 – 7.65 (m, 3H), 7.27 – 7.40 (m, 1H),
13
4.58 (d, J = 6.3 Hz, 2H), 3.27 (sept, J = 6.9 Hz, 1H), 1.41 (d, J = 6.9 Hz, 6H); C NMR (100 MHz,
CDCl3) δ 176.4, 161.4, 149.1, 148.8, 141.5, 140.1, 135.5, 134.0, 131.6 (X2), 131.0 (X2), 123.5, 118.5,
112.2, 40.6, 33.3, 22.9 (X2); HRMS (ESI-MS):Calc. for C20H19N4OS [(M+H)+]: 363.1280, Found:
363.1308.
N-benzyl-5-(4-cyanophenyl)-2-isopropylthiazole-4-carboxamide (14g)
1
White solid (160 mg, 66%). H NMR (300 MHz, CDCl3) δ ppm 7.80 (s, 1H), 7.67 (d, J = 8.4 Hz,
2H), 7.61 (d, J = 8.4 Hz, 2H), 7.32 – 7.16 (m, 5H), 4.52 (d, J = 6.1 Hz, 2H), 3.20 (sept, J = 6.9 Hz,
1H), 1.35 (d, J = 6.9 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 176.4, 161.3, 141.9, 139.9, 138.3,
135.8, 131.7 (X2), 131.2 (X2), 128.8 (X2), 127.9 (X2), 127.6, 118.7, 112.3, 43.3, 33.4, 23.0 (X2);
HRMS (ESI-MS):Calc. for C21H20N3OS [(M+H)+]:362.1327, Found:362.1328.
(4-cyanophenyl)-N-(3,5-dichlorobenzyl)-2-isopropylthiazole-4-carboxamide (14h)
White solid (125 mg, 55%). 1H NMR (400 MHz, CDCl3) δ ppm 8.01 (t, J = 6.1 Hz, 1H), 7.70 (d, J =
8.6 Hz, 2H), 7.66 (d, J = 8.6 Hz, 2H), 7.39 (d, J = 2.1 Hz, 1H), 7.35 (d, J = 8.3 Hz, 1H), 7.20 (dd, J =
13
8.2, 2.1 Hz, 1H), 4.61 (d, J = 6.4 Hz, 2H), 3.28 (sept, J = 6.9 Hz, 1H), 1.43 (d, J = 6.9 Hz, 6H); C
NMR (75 MHz, CDCl3) δ 176.5, 161.4, 141.6, 140.2, 135.6, 134.4, 134.3, 134.0, 131.7 (X2), 131.1
24

ACCEPTED MANUSCRIPT
(X2), 130.8, 129.5, 127.4, 118.7, 112.5, 40.7, 33.4, 23.0 (X2); HRMS (ESI-MS):Calc. for
C21H18N3OSCl2 [(M+H)+]: 430.0548, Found: 430.551.
5-(4-cyanophenyl)-N-(4-fluorobenzyl)-2-isopropylthiazole-4-carboxamide (14i)
White solid (180 mg, 71%). 1H NMR (300 MHz, CDCl3) δ ppm 7.86 (t, J = 5.6 Hz, 1H), 7.72 (d, J =
8.6 Hz, 2H), 7.67 (d, J = 8.4 Hz, 2H), 7.35 – 7.27 (m, 2H), 7.02 (t, J = 8.6 Hz, 2H), 4.53 (d, J = 6.2
Hz, 2H), 3.27 (sept, J = 6.9 Hz, 1H), 1.41 (d, J = 6.9 Hz, 6H); 13C NMR (125 MHz, CDCl3) δ 176.5,
162.3 (d, 1JC,F = 245.5Hz), 161.3, 141.8, 140.0, 135.7, 134.2, 134.1, 131.7 (X2), 131.1 (X2), 129.5 (d,
3JC,F = 8.0 Hz), 118.7, 115.6 (d, 2JC,F = 21.4 Hz), 112.4, 42.5, 33.4, 23.0 (X2); HRMS (ESI-MS):Calc.
for C21H19N3OSF [(M+H)+]: 380.1233, Found: 380.1234.
N-(4-chlorobenzyl)-5-(4-cyanophenyl)-2-isopropylthiazole-4-carboxamide (14j)
White solid (180 mg, 68%). 1H NMR (300 MHz, CDCl3) δ ppm 7.87 (t, J = 5.5 Hz, 1H), 7.72 (d, J =
8.5 Hz, 2H), 7.67 (d, J = 8.5 Hz, 2H), 7.32 – 7.24 (m, 4H), 4.53 (d, J = 6.2 Hz, 2H), 3.27 (sept, J = 6.9
13
Hz, 1H), 1.42 (d, J = 6.9 Hz, 6H); C NMR (125 MHz, CDCl3) δ 176.5, 161.4, 141.7, 140.1, 136.9,
135.7, 133.4, 131.7 (X2), 131.2 (X2), 129.2 (X2), 128.9 (X2), 118.7, 112.4, 42.6, 33.4, 23.0 (X2);
HRMS (ESI-MS):Calc. for C21H19N3OSCl [(M+H)+]: 396.0937, Found: 396.0943.
N-(4-chloro-3-fluorophenyl)-5-(4-cyanophenyl)-2-isopropylthiazole-4-carboxamide (14k)
1
White solid (160 mg, 54%). H NMR (500 MHz, CDCl3) δ ppm 9.44 (s, 1H), 7.85 (dd, J = 6.5, 2.6
Hz, 1H), 7.76 – 7.66 (m, 4H), 7.45 (ddd, J = 8.9, 4.1, 2.7 Hz, 1H), 7.09 (t, J = 8.8 Hz, 1H), 3.34 (sept,
J = 6.9 Hz 1H), 1.48 (d, J = 6.9 Hz, 6H); 13C NMR (75 MHz, CDCl3) δ 176.7, 159.1, 154.9 (d, 1JC,F
246.3Hz), 141.4, 141.2, 135.3, 134.4, 134.4, 131.8 (X2), 131.1 (X2), 122.0, 121.3 (d, 2JC,F = 18.5Hz),
=
3
2
119.5 (d, JC,F = 6.7 Hz), 118.6, 116.6 (d, JC,F = 21.4Hz), 112.7, 33.5, 23.0 (X2); HRMS (ESI-
MS):Calc. for C20H16N3OFClS [(M+H)+]: 400.0697, Found: 400.0693.
(R)-5-(4-cyanophenyl)-2-isopropyl-N-(1-(naphthalen-1-yl)ethyl)thiazole-4-carboxamide (14l)
25

ACCEPTED MANUSCRIPT
White solid (145 mg, 51%). 1H NMR (400 MHz, CDCl3) δ ppm 7.88 (d, J = 8.5 Hz, 1H), 7.86 – 7.80
(m, 4H), 7.70 (d, J = 8.6 Hz, 2H), 7.65 (d, J = 8.6 Hz, 2H), 7.52 – 7.43 (m, 3H), 5.38 (qn, J =7.0 Hz,
1H), 3.30 (sept, J = 6.9 Hz, 1H), 1.68 (d, J = 6.9 Hz, 3H), 1.44 (d, J = 1.9 Hz, 3H), 1.42 (d, J = 1.9
Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 176.4, 160.6, 142.0, 140.7, 139.8, 135.8, 133.5, 132.8, 131.7
(X2), 131.1 (X2), 128.6, 128.0, 127.7, 126.3, 126.0, 124.9, 124.7, 118.7, 112.3, 48.8, 33.5, 23.1 (X2),
22.1; HRMS (ESI-MS):Calc. for C26H24N3OS [(M+H)+]: 426.1640, Found: 426.1646.
N-(1-(4-bromophenyl)ethyl)-5-(4-cyanophenyl)-2-isopropylthiazole-4-carboxamide (14m)
White solid (165 mg, 54%). 1H NMR (400 MHz, CDCl3) δ ppm 7.77 (d, J = 8.2 Hz, 1H), 7.68 (d, J =
8.6 Hz, 2H), 7.65 (d, J = 8.6 Hz, 2H), 7.45 (d, J = 8.5 Hz, 2H), 7.24 (d, J = 8.5 Hz, 2H), 5.15(qn, J
=7.0 Hz, 1H), 3.29 (sept, J = 6.9 Hz, 1H), 1.55 (d, J = 7.0 Hz, 3H), 1.43 (d, J = 6.9 Hz, 6H); 13C
NMR (100 MHz, CDCl3) δ 176.5, 160.5, 142.5, 141.8, 140.0, 135.7, 131.8 (X2), 131.7 (X2), 131.1
(X2), 128.0 (X2), 121.2, 118.7, 112.3, 48.2, 33.4, 23.1 (X2), 22.1; HRMS (ESI-MS):Calc. for
C22H21N3OSBr [(M+H)+]: 454.0589, Found: 454.0586.
5-(4-cyanophenyl)-2-isopropyl-N-(1-(p-tolyl)ethyl)thiazole-4-carboxamide (14n)
White solid (180 mg, 69%). 1H NMR (400 MHz, CDCl3) δ ppm 7.76 (d, J = 8.3 Hz, 1H), 7.70 (d, J =
8.6 Hz, 2H), 7.65 (d, J = 8.6 Hz, 2H), 7.27 (d, J = 7.9 Hz, 2H), 7.16 (d, J = 7.9 Hz, 2H), 5.18 (qn, J
=7.5 Hz, 1H), 3.28 (Sept, J = 6.9 Hz, 1H), 2.33 (s, 3H), 1.56 (d, J = 6.9 Hz, 3H), 1.43 (d, J = 1.5 Hz,
3H), 1.41 (d, J = 1.5 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 176.3, 160.5, 142.1, 140.3, 139.7,
137.1, 135.8, 131.7 (X2), 131.2 (X2), 129.4 (X2), 126.2 (X2), 118.7, 112.2, 48.4, 33.4, 23.1 (X2),
22.2, 21.2; HRMS (ESI-MS):Calc. for C23H24N3OS [(M+H)+]: 390.1640, Found: 390.1645.
(S)-5-(benzo[d][1,3]dioxol-5-yl)-2-isopropyl-N-(1-phenylethyl)thiazole-4-carboxamide (15a)
1
Yellow semisolid (120 mg, 48%). H NMR (500 MHz, CDCl3) δ ppm 7.74 (d, J = 8.2 Hz, 1H), 7.38
(d, J = 7.2 Hz, 2H), 7.33 (t, J = 7.6 Hz, 2H), 7.28 – 7.22 (m, 1H), 7.10 (d, J = 1.6 Hz, 1H), 7.04 (dd, J
= 8.0, 1.7 Hz, 1H), 6.80 (d, J = 8.0 Hz, 1H), 5.97 (s, 1H), 5.25 (qn, J =7.0 Hz, 1H), 3.24 (sept, J = 6.9
13
Hz, 1H), 1.57 (d, J = 6.9 Hz, 3H), 1.41 (d, J = 1.5 Hz, 3H), 1.39 (d, J = 1.5 Hz, 3H); C NMR (100
26

ACCEPTED MANUSCRIPT
MHz, CDCl3) δ 174.5, 160.9, 148.2, 147.3, 143.6, 142.2, 140.7, 128.7 (X2), 127.2, 126.3 (X2), 124.3,
124.2, 111.0, 107.9, 101.4, 48.4, 33.3, 23.1 (X2), 22.2; HRMS (ESI-MS):Calc. for C22H23N2O3S
[(M+H)+]: 395.1429, Found: 395.1459.
(R)-5-(benzo[d][1,3]dioxol-5-yl)-2-isopropyl-N-(1-phenylethyl)thiazole-4-carboxamide (15b)
White solid (125 mg, 50%). 1H NMR (400 MHz, CDCl3) δ ppm 7.74 (d, J = 8.4 Hz, 1H), 7.38 (d, J =
7.0 Hz, 2H), 7.34 (t, J = 7.5 Hz, 2H), 7.29 – 7.23 (m, 1H), 7.11 (d, J = 1.7 Hz, 1H), 7.04 (dd, J = 8.0,
1.8 Hz, 1H), 6.80 (d, J = 8.0 Hz, 1H), 5.97 (s, 2H), 5.25 (qn, J =7.0 Hz, 1H), 3.24 (sept, J = 6.9 Hz,
1H), 1.57 (d, J = 6.9 Hz, 3H)1.41 (d, J = 1.3 Hz, 3H), 1.39 (d, J = 1.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 174.5, 160.9, 148.2, 147.3, 143.6, 142.2, 140.7, 128.7 (X2), 127.2, 126.3 (X2), 124.3, 124.2,
111.0, 107.9, 101.4, 48.4, 33.3, 23.1 (X2), 22.2; HRMS (ESI-MS):Calc. for C22H23N2O3S [(M+H)+]:
395.1429, Found: 395.1438.
5-(benzo[d][1,3]dioxol-5-yl)-N-(3,4-dimethoxyphenethyl)-2-isopropylthiazole-4-carboxamide
(15c)
Yellow solid (165 mg, 58%). 1H NMR (500 MHz, CDCl3) δ ppm 7.58 (t, J = 5.8 Hz, 1H), 7.11 (d, J =
1.7 Hz, 1H), 7.04 (dd, J = 8.0, 1.8 Hz, 1H), 6.81 (d, J = 8.0 Hz, 2H), 6.78 (d, J = 1.8 Hz, 1H), 6.76 (s,
1H), 5.99 (s, 2H), 3.86 (s, 3H)), 3.85 (s, 3H), 3.60 (q, J = 6.7 Hz, 2H), 3.21 (sept, J = 6.9 Hz, 1H),
2.84 (t, J = 7.2 Hz, 2H), 1.38 (d, J = 6.9 Hz, 6H); 13C NMR (100 MHz, CDCl3) δ 174.3, 161.8, 149.0,
148.2, 147.6, 147.3, 142.0, 140.8, 131.8, 124.3, 124. 2, 120.8, 112.1, 111.4, 111.0, 107.9, 101.4, 56.0,
55.9, 40.8, 35.6, 33.2, 22.9 (X2); HRMS (ESI-MS):Calc. for C24H27N2O5S [(M+H)+]: 455.1641,
Found: 455.1650.
(5-(benzo[d][1,3]dioxol-5-yl)-2-isopropylthiazol-4-yl)(morpholino)methanone (15d)
1
White solid (133 mg, 59%). H NMR (500 MHz, CDCl3) δ ppm 6.99 – 6.94 (m, 2H), 6.82 (dd, J =
7.7, 0.7 Hz, 1H), 6.00 (s, 2H), 3.73 (t, J = 4.8 Hz, 2H), 3.65 (t, J = 5.0 Hz, 2H), 3.32 (t, J = 4.8 Hz,
13
2H), 3.32 – 3.23 (m, 1H), 3.19 ((t, J = 5.0 Hz, 2H), 1.41 (d, J = 6.9 Hz, 6H); C NMR (100 MHz,
CDCl3) δ 176.8, 164.9, 148.3, 148.28, 142.6, 135.8, 124.2, 122.7, 108.9 (X2), 101.6, 66.6, 66.5, 47.2,
27

ACCEPTED MANUSCRIPT
42.4, 33.5, 23.2 (X2); HRMS (ESI-MS):Calc. for C18H21N2O4S [(M+H)+]: 361.1222, Found:
361.1221.
5-(benzo[d][1,3]dioxol-5-yl)-N-(benzo[d][1,3]dioxol-5-ylmethyl)-2-isopropylthiazole-4-
carboxamide (15e)
1
Brown semisolid (120 mg, 45%). H NMR (500 MHz, CDCl3) δ ppm 7.78 (bs, 1H), 7.12 (d, J = 1.6
Hz, 1H), 7.05 (dd, J = 8.0, 1.6 Hz, 1H), 6.84 (s, 1H), 6.82 – 6.78 (m, 2H), 6.75 (d, J = 7.9 Hz, 1H),
5.97 (s, 2H), 5.92 (s, 2H), 4.47 (d, J = 6.1 Hz, 2H), 3.21 (sept, J = 6.9 Hz, 1H), 1.38 (d, J = 6.9 Hz,
6H); 13C NMR (100 MHz, CDCl3) δ 174.4, 161.5, 148.6, 147.8, 147.2, 146.8, 142.3, 140.5, 132.4,
124.2, 124.1, 121.0, 110.9, 108.4, 108.2, 107.8, 101.3, 100.9, 42.9, 33.1, 22.9 (X2); HRMS (ESI-
MS):Calc. for C22H21N2O5S [(M+H)+]: 425.1171, Found: 425.1175.
5-(benzo[d][1,3]dioxol-5-yl)-2-isopropyl-N-(pyridin-3-ylmethyl)thiazole-4-carboxamide (15f)
Brown solid (110 mg, 46%). 1H NMR (500 MHz, CDCl3) δ ppm 8.59 (d, J = 1.6 Hz, 1H), 8.51 (dd, J
= 4.7, 1.3 Hz, 1H), 7.88 (t, J = 5.8 Hz, 1H), 7.69 (dt, J = 7.8, 1.8 Hz, 1H), 7.26 – 7.23 (m, 1H), 7.11
(d, J = 1.7 Hz, 1H), 7.05 (dd, J = 8.0, 1.8 Hz, 1H), 6.82 (d, J = 8.0 Hz, 1H), 5.98 (s, 2H), 4.59 (d, J =
6.3 Hz, 2H), 3.22 (sept, J = 6.9 Hz, 1H), 1.39 (d, J = 6.9 Hz, 6H); 13C NMR (100 MHz, CDCl3) δ
174.6, 161.8, 149.1, 148.6, 148.2, 147.2, 142.6, 140.2, 135.7, 134.4, 124.2, 124.0, 123.6, 110.9, 107.9,
101.3, 40.5, 33.2, 22.9 (X2); HRMS (ESI-MS):Calc. for C20H20N3O3S [(M+H)+]: 382.1225, Found:
382.1232.
(S)-5-(4-cyanophenyl)-2-cyclohexyl-N-(1-phenylethyl)thiazole-4-carboxamide (16a)
White solid (175 mg, 70%). 1H NMR (500 MHz, CDCl3) δ ppm 7.80 (d, J = 8.4 Hz, 1H), 7.69 (d, J =
8.5 Hz, 2H), 7.64 (d, J = 8.5 Hz, 2H), 7.39 – 7.36 (m, 2H), 7.36 – 7.32 (m, 2H), 7.28 – 7.24 (m, 1H),
5.21 (qn, J = 7.0 Hz, 1H), 2.96 (tt, J = 11.5, 3.6 Hz, 1H), 2.16 (d, J = 12.5 Hz, 2H), 1.90 – 1.86 (m,
13
2H), 1.79 – 1.75 (m, 1H), 1.56 (d, J = 10.8 Hz, 3H), 1.55 – 1.38 (m, 4H), 1.35 – 1.27 (m, 1H); C
NMR (100 MHz, CDCl3) δ 175.4, 160.5, 143.3, 141.9, 139.5, 135.8, 131.6 (X2), 131.1 (X2), 128.7
28