Synthesis, in vitro anti-inflammatory activity and molecular docking studies of novel 4,5-diarylthiophene-2-carboxamide derivatives

Article abstract of DOI:10.1007/s12039-016-1209-7

A series of novel 4,5-diarylthiophene-2-carboxamide containing alkyl, cycloalkyl, aryl, aryl alkyl and heterocyclic alkyl moieties were synthesized, characterized and subsequently evaluated for anti-inflammatory property. Among the novel compounds, the inhibition of bovine serum albumin denaturation assay revealed that the aryl and aryl alkyl derivatives of 4,5-diarylthiophene-2-carboxamide showed anti-inflammatory activity comparable to the standard drug diclofenac sodium whereas alkyl and cycloalkyl amide derivatives showed less activity. Docking studies with these compounds against cyclooxygenase-2 receptor (PDB 1D: 1PXX) indicated that they exhibit specific interactions with key residues located in the site of the COX2 structure, which corroborates the hypothesis that these molecules are potential ligands of COX2. The analysis of the docking results, which takes into account the hydrophilic and hydrophobic interactions between the ligands and the target, identified N-(4-bromophenyl)-4,5-bis(4-hydroxyphenyl)thiophene-2-carboxamide (6k) having high binding free energy of ?11.67 kcal /mole (comparable with standard diclofenac sodium) and the best docking score, indicating effective binding of the compound 6k at the active site. [Figure not available: see fulltext.]

Full text of DOI:10.1007/s12039-016-1209-7

c
J. Chem. Sci. ꢀ Indian Academy of Sciences.
DOI 10.1007/s12039-016-1209-7
REGULAR ARTICLE
Synthesis, in vitro anti-inflammatory activity and molecular docking
studies of novel 4,5-diarylthiophene-2-carboxamide derivatives
T SHANMUGANATHANa,b,∗, K PARTHASARATHYc, M VENUGOPALd, Y ARUNe,
N DHATCHANAMOORTHYa and A A M PRINCEb
aOrchid Pharma Ltd, R & D Centre, Chennai 600 119, India
bRamakrishna Mission Vivekananda College, Department of Chemistry, Mylapore, Chennai 600 004, India
cDepartment of Chemistry, Siddha Central Research Institute, Central Council for Research in Siddha,
Chennai 600 106, India
dVen Biotech Private Limited, Chennai, India
eOrganic Chemistry Division, Central Leather Research Institute (CSIR), Adyar, Chennai 600 020, India
Email: t_shanmuganathan09@yahoo.com
MS received 29 September 2016; revised 1 November 2016; accepted 12 November 2016
Abstract. A series of novel 4,5-diarylthiophene-2-carboxamide containing alkyl, cycloalkyl, aryl, aryl
alkyl and heterocyclic alkyl moieties were synthesized, characterized and subsequently evaluated for anti-
inflammatory property. Among the novel compounds, the inhibition of bovine serum albumin denaturation
assay revealed that the aryl and aryl alkyl derivatives of 4,5-diarylthiophene-2-carboxamide showed anti-
inflammatory activity comparable to the standard drug diclofenac sodium whereas alkyl and cycloalkyl amide
derivatives showed less activity. Docking studies with these compounds against cyclooxygenase-2 receptor
(PDB 1D: 1PXX) indicated that they exhibit specific interactions with key residues located in the site of the
COX2 structure, which corroborates the hypothesis that these molecules are potential ligands of COX2. The
analysis of the docking results, which takes into account the hydrophilic and hydrophobic interactions between
the ligands and the target, identified N-(4-bromophenyl)-4,5-bis(4-hydroxyphenyl)thiophene-2-carboxamide
(6k) having high binding free energy of −11.67 kcal/mole (comparable with standard diclofenac sodium) and
the best docking score, indicating effective binding of the compound 6k at the active site.
Keywords. Demethylation; 4,5-diarylthiophene-2-carboxamide derivatives; anti-inflammatory; molecular
docking.
1. Introduction
Desoxyanisoin (1) is one of the most versatile
synthetic intermediates and widely utilized in the syn-
thesis of complex heterocyclic compounds. Various
bioactive molecules have been prepared by the effi-
Non-steroidal anti-inflammatory drugs (NSAID) such
as indomethacin and diclofenac are broadly used ther-
apeutic drugs, primarily for pain, inflammation and cient utilization of desoxyanisoin.7 15 However, there
arthritis.1 The beneficial anti-inflammatory and anal- are very few reports available in the literature on the
gesic effects of NSAIDs is due to their inhibition of synthesis of thiophene derivatives from desoxyanisoin.
cyclooxygenase (COX) thereby inhibiting prostaglan- Considering the synthetic utility of desoxyanisoin, we
dins synthesis.2 Among the isoforms of COX, the envisaged to synthesize novel thiophene heterocycles,
inducible COX-2 is associated with inflammatory con- since sulphur possesses high therapeutic properties and
ditions whereas the constitutively expressed COX-1 its incorporation will substantially augment the biolog-
is responsible for the cytoprotective effects of pros- ical activity.
taglandins. The 2,3-diarylthiophene (DAT) pharma-
The importance of cis-stilbene moiety in diaryl
cophore is of importance following the report on the heterocyclic compounds is well-documented as respon-
non-ulcerogenic, anti-inflammatory properties of ‘DuP sible for receptor occupancy at the active site of COX
697’ through the selective inhibition of COX-2.3 Fur- enzyme,16,17 whereas the nature of para-substituents on
ther exploitation of DAT template resulted in the the aryl rings determine COX-2 selectivity.18,19 Further,
development of celecoxib,4 rofecoxib5 and valdecoxib6 the presence of methoxy group as an aryl substituent
which are approved for clinical use.
has been reported for the anti-inflammatory drugs such
as Anitrazifen, Flumizole, Pamicogrel and Mofezolac
whereas, free/derivatized amide group attached to the
∗For correspondence

T Shanmuganathan et al.
carbon solvent signal for CDCl3, δH 7.26 ppm, δC 77.0 ppm,
heterocyclic ring has been reported for COX inhibitors,
such as Ethenzamide, Tenidap and Picotamide. This
investigation is prompted mainly by the aforementioned
anti-inflammatory activities of diarylheterocyclic ring
system in addition to the recognized substituents to
diaryl as well as heterocyclic moieties (Figure 1). In
view of these observations, it was thought worthwhile
to synthesise a series of 4,5-diarylthiophene-2-carbox-
amide derivatives via Vilsmeier procedure followed by
the incorporation with 2-mercaptoacetic acid to yield
substituted thiophenes and to evaluate them for their
anti-inflammatory activity.
δ6-DMSO, δH 2.50 ppm, δC 40.0 ppm. Proton and carbon
spectra were typically obtained at room temperature. Mass
spectra were recorded on ESI – Perkin Elmer Sciex, API
3000 mass spectrometer. Pre-coated silica gel GF254 plates
from Merck were used for thin layer chromatography (TLC).
The elemental analyses were recorded in Thermo Finnigan
Flash EA 1112 elemental analyser.
2.2 Synthesis
2.2a Synthesis of 2,3-bis (4-methoxy phenyl)-3-chloro-2-
prop-2-ene aldehyde (2): 0.05 mol (7.66 g) of phosphorous
oxychloride (POCl3) was added drop wise over a period of
15–30 min with stirring at 0–5◦C to 20 mL of dimethylfor-
mamide. The mass was maintained at 0–5◦C over 30 min
and a solution of desoxyanisoin 0.04 mol (10 g) in dimethyl-
formamide (50 mL) at 0–5◦C was added under stirring. The
reaction mass was heated to 70–75◦C and maintained for 4 h.
2. Experimental
2.1 Materials and methods
All the chemicals and reagents used were lab grade material The progress of the reaction was monitored using TLC
procured from Alfa aesar. All the solvents used were pur- (Toluene). After completion, the reaction mixture was cooled
chased from commercial suppliers and were used without and poured slowly into 25% solution of sodium acetate in
further purification. The melting points were determined water (100 mL). The product was filtered and washed with
using Buchi apparatus by the open capillary tube method water, followed by slurry wash with ethanol (100 mL) which
and are uncorrected. The IR spectra were recorded in Perkin- after drying gave 9.1 g (78% yield) of the compound 2.
Elmer series 2000 FTIR spectrophotometer using KBr pel-
White powder, M.p. 145–147◦C. [Lit.20; 158◦C]. IR (KBr)
let. 1H NMR and 13C NMR spectra were obtained in CDCl3, cm−1: 2932, 1680, 1513, 1442, 1080, 813, 772. H NMR
DMSO-d6 on a Bruker spectrometer at 400 and 100 MHz, (400 MHz, CDCl3): δ 9.66 (s, 1H), 7.52 (d, J = 7.8 Hz, 2H),
respectively. The chemical shifts are reported in ppm (δ) rel- 7.25-7.22 (m, 2H), 6.99–6.91 (m, 4H), 3.89 (s, 3H), 3.85 (s,
ative to tetramethylsilane as internal standard, coupling con- 3H). 13C NMR (100 MHz, CDCl3): δ 190.5, 162.1, 159.7,
stants (J) are in hertz (Hz). Spin multiplicities are given as 155.1, 139.8, 132.4, 132.1, 131.1, 130.6, 128.4, 126.7, 114.2,
s (singlet), d (doublet), t (triplet), dd (doublet of doublet), 113.9, 55.8, 55.5. ESI-MS m/z Calculated 302.1. Found:
bs (broad signal) and m (multiplet). Residual proton and 303.1 [M + H]+.
1
O
O
O
O
O
O
O
OH
N
N
H
N
N
N
O
CF3
N
S
N
N
O
O
O
O
Anitrazifen
Flumizole
Mofezolac
Pamicogrel
O
S
O
O
NH2
NH
O
NH
Cl
O
O
OH
N
N
N
NH2
O
Ethenzamide
Tenidap
Picotamide
Figure 1. Anti-inflammatory agents based on diaryl heterocyclic and amide based compounds.

4,5-diarylthiophene-2-carboxamide derivatives
2.2b Synthesis of 4,5-bis(4-methoxyphenyl)thiophene-2- mixture of aluminium chloride (9.38 g, 0.0704 mole) in
carboxylic acid (3): 2,3-bis (4-methoxy phenyl)-3-chloro- chlorobenzene (60 mL) at 25–30◦C. The reaction mixture
2-prop-2-ene aldehyde 2 (5 g, 0.0165 mole) was added to was heated to 95–105◦C and maintained for 3 h. The pro-
a solution of potassium hydroxide (4 g, 0.714 mole) and 2- gress of the reaction was monitored using TLC (hexane: ethyl
mercapto acetic acid (3.1 g, 0.034 mole) in methanol:water acetate 3:7). After completion of the reaction, aqueous HCl
(40 mL:10 mL) mixture at room temperature. The mixture (1:1, 50 mL) was added to the mass at 25–30◦C. The product
was refluxed for 4 h, and reaction was monitored using TLC was extracted with ethyl acetate (50 mL × 2) and the organic
(hexane: ethyl acetate 3:7). After completion, the reaction layer was washed with water. Ethyl acetate was evaporated
mixture was cooled to room temperature and slowly acidi- under vacuum and the residue was triturated with dichlo-
fied with concentrated HCl over 30–45 min at 25–30◦C. The romethane (100 mL), filtered to get compound 4. 4.85 g.
product 3 was filtered, washed with water and dried to get (88% yield).
compound 3. 4 g (71% yield).
Light green powder, M.p. 240–243◦C. IR (KBr) cm−1
:
Yellow powder, M.p. 211–213◦C. [Lit.20; 215 ◦C]. IR 3428, 3318, 1639, 1545, 1442, 1255, 1069, 829. H NMR
(KBr) cm−1: 2933, 2542, 1668, 1546, 1449, 1247, 1033, 827. (400 MHz, CDCl3+ DMSO-d6): δ 8.48 (bs, 1H), 8.19 (bs,
1H NMR (400 MHz, CDCl3): δ 10.7 (bs, 1H), 7.87 (s, 1H), 1H), 7.75 (s, 1H), 7.17 (d, J = 8.5 Hz, 2H), 7.11 (d, J = 8.4
7.27 (d, J = 8.6 Hz, 2H), 7.20 (d, J = 8.6 Hz, 2H), 6.85–6.81 Hz, 2H), 6.77–6.75 (m, 4H). 13C NMR (100 MHz, CDCl3+
(m, 4H), 3.83 (s, 3H), 3.81 (s, 3H). 13C NMR (100 MHz, DMSO-d6): δ 164.3, 157.5, 156.4, 144.9, 137.8, 136.2,
CDCl3): δ 168.0, 159.9, 159.1, 147.0, 138.4, 137.9, 130.6, 130.9, 130.4, 130.0, 127.1, 124.9, 115.6, 115.5. ESI-MS m/z
130.3, 129.5 128.1, 125.9, 114.3, 114.1, 55.5, 55.4. ESI-MS Calculated 312.0. Found: 313.0 [M + H]+.
m/z Calculated 340.1. Found: 339.1 [M − H]−.
1
2.2c Synthesis of 4,5-bis(4-hydroxyphenyl)thiophene-2- 2.2d General synthetic procedure for the title compounds
carboxylic acid (4): 4,5-bis(4-methoxyphenyl)thiophene- 4,5-bis(4-methoxyyphenyl)-substituedthiophene-2-carboxamide
2-carboxylic acid 3 (6 g, 0.0176 mole) was added to the (5a–5o): Dimethylaminopyridine (1.2 mmol) was added to
Table 1. Reaction time and yield of the product.
Entry
R
R1
Time (h)
Producta
Yieldb (%)
1
2
3
4
5
6
7
8
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
H
H
H
H
H
H
H
H
Propyl
isopropyl
butyl
cyclopropyl
cyclopentyl
cyclohexyl
cycloheptyl
Phenyl
4-fluorophenyl
4-chlorophenyl
4-bromophenyl
benzyl
3
7
4
3
3
3
3
5
4
4
6
4
4
4
4.5
5
5
5
5
5
5
5
3
3
6
6
5
5
5
4
5a
5b
5c
5d
5e
5f
5g
5h
5i
76
78
80
75
76
75
72
85
90
88
87
80
85
86
90
79
80
75
85
89
86
82
80
82
78
76
95
93
90
80
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
5j
5k
5l
4-fluorobenzyl
4-(trifluoromethyl)benzyl
2-(thiophene-2-yl)ethyl
Propyl
5m
5n
5o
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
isopropyl
butyl
cyclopropyl
cyclopentyl
cyclohexyl
cycloheptyl
Phenyl
4-fluorophenyl
4-chlorophenyl
4-bromophenyl
Benzyl
H
H
H
H
H
H
4-fluorobenzyl
4-(trifluoromethyl)benzyl
2-(thiophene-2-yl)ethyl
6m
6n
6o
a All the products were characterized by NMR, IR and Mass spectroscopy; bIsolated yield.

T Shanmuganathan et al.
a mixture of 4,5-bis(4-methoxyphenyl)thiophene-2-carbox- for C23H25NO3S: C, 69.84; H, 6.36; N, 3.54%. Found: C,
ylic acid (3) (1.0 mmol), 2-(1H-Benzotriazole-1-yl)-1,1,3,3- 69.48; H, 6.24; N, 3.56%.
tetramethyluronium tetrafluoroborate (TBTU) (1.2 mmol)
in acetonitrile (3 mL) at 25–30◦C and stirred for 30 min.
2.2d4 N-cyclopropyl-4,5-bis(4-methoxyphenyl)thiophene-
An appropriate amine (1.2 mmol) was added to the reac-
tion mixture at 25–30◦C and progress of the reaction was
monitored by TLC. (hexane: ethyl acetate: acetic acid 4 mL:
4 mL: 2 drops). After completion of the reaction, the mixture
was poured into water and the product was extracted with
ethyl acetate. The organic layer was washed with 5% aque-
ous HCl solution, followed by a saturated solution of sodium
bicarbonate and finally with water. The organic layer was
separated and dried over anhydrous sodium sulphate. The
solvent was evaporated under vacuum to get the product. The
reaction times and yields of the product are shown in Table 1.
2-carboxamide (5d): Prepared from 3 and cyclopropyl
amine. Pale brown powder, M.p. 160–162◦C. IR (KBr)
cm−1: 3349, 2931, 2836, 1626, 1550, 1249, 1036, 832, 798.
1H NMR (400 MHz, DMSO-d6): δ 8.49 (d, J = 4 Hz, 1H),
7.79 (s, 1H), 7.21–7.1 (m, 4H), 6.92–6.89 (m, 4H), 3.76
(s, 3H), 3.75 (s, 3H), 2.84–2.79 (m, 1H), 0.73–0.69 (m,
2H), 0.58–0.54 (m, 2H). 13C NMR (100 MHz, DMSO-d6):
δ 162.1, 159.2, 158.4, 141.1, 137.1, 130.8, 130.1, 129.8,
127.9, 125.6, 114.3, 114.0, 55.2, 55.1, 22.9, 5.8. ESI-MS
m/z Calculated 379.1. Found: 380.1 [M + H]+. Anal.
Calculated for C22H21NO3S: C, 69.63; H, 5.58; N, 3.69%.
Found: C, 69.52; H, 5.48; N, 3.58%.
2.2d1 4,5-bis(4-methoxyphenyl)-N-propylthiophene-
2-carboxamide (5a): Prepared from 3 and propyl amine.
Off-white powder, M.p. 56–59◦C. IR (KBr) cm−1: 3306,
2.2d5 N-cyclopentyl-4,5-bis(4-methoxyphenyl)thiophene-
2-carboxamide (5e): Prepared from 3 and cyclopentyl
1
amine. Off-white powder, M.p. 193–195◦C. IR (KBr) cm−1
:
2931, 2835, 1622, 1556, 1247, 1032, 829, 794. H NMR
1
(400 MHz, DMSO-d6): δ 8.50 (t, J = 5.6 Hz, 1H), 7.83 (s,
1H), 7.23–7.16 (m, 4H), 6.93–6.89 (m, 4H), 3.76 (s, 3H),
3.75 (s, 3H), 3.24 (quartet, J = 6.6 Hz, 2H), 1.58 (sextet,
J = 7.4 Hz, 2H), 0.92 (t, J = 7.4 Hz, 3H). 13C NMR (100
MHz, DMSO-d6): δ 160.9, 159.2, 158.4, 140.9, 137.4,
137.1, 130.6, 130.1, 129.8, 127.9, 125.6, 114.3, 114.0,
55.2, 55.1, 40.9, 22.5, 11.5. ESI-MS m/z Calculated 381.1.
Found: 382.1 [M + H]+. Anal. Calculated for C22H23NO3S:
C, 69.26; H, 6.08; N, 3.67%. Found: C, 69.12; H, 6.00; N,
3.52%.
3244, 2952, 2834, 1613, 1557, 1249, 1031, 829, 795. H
NMR (400 MHz, DMSO-d6): δ 8.32 (d, J = 7.3 Hz, 1H),
7.89 (s, 1H), 7.22-7.17 (m, 4H), 6.92–6.89 (m, 4H), 4.22–
4.17 (m, 1H), 3.76 (s, 3H), 3.75 (s, 3H), 1.90–1.86 (m,
2H), 1.69(m, 2H), 1.56–1.49 (m, 4H). 13C NMR (100 MHz,
DMSO-d6): δ 160.5, 159.2, 158.4, 140.9, 137.5, 137.1,
130.8, 130.1, 129.8, 127.9, 125.6, 114.3, 114.0, 55.2, 55.1,
50.9, 32.2, 23.7. ESI-MS m/z Calculated 407.1. Found:
408.1 [M + H]+. Anal. Calculated for C24H25NO3S: C,
70.73; H, 6.18; N, 3.44%. Found: C, 70.69; H, 6.28; N,
3.48%.
2.2d2 N-isopropyl-4,5-bis(4-methoxyphenyl)thiophene-
2-carboxamide (5b): Prepared from 3 and isopropyl
2.2d6 N-cyclohexyl-4,5-bis(4-methoxyphenyl)
amine. White powder, M.p. 222–225◦C. IR (KBr) cm−1
:
thiophene-2-carboxamide (5f): Prepared from 3 and
cyclohexyl amine. White powder, M.p. 206–207◦C. IR
(KBr) cm−1: 3236, 2928, 2852, 1627, 1563, 1244, 1034,
1
3292, 2931, 2837, 1620, 1558, 1248, 1032, 836, 791. H
NMR (400 MHz, DMSO-d6): δ 8.28 (d, J = 7.8 Hz, 1H),
7.88 (s, 1H), 7.22–7.17 (m, 4H), 6.93–6.89 (m, 4H), 4.08
(septet, J = 6.8 Hz, 1H), 3.76 (s, 3H), 3.75 (s, 3H), 1.19 (d,
J = 6.4 Hz, 6H). 13C NMR (100 MHz, DMSO-d6): δ 160.0,
159.2, 158.4, 140.9, 137.6, 137.1, 130.7, 130.1, 129.8,
127.9, 125.7, 114.3, 114.0, 55.2, 55.1, 41.1, 22.4. ESI-MS
m/z Calculated 381.1. Found: 382.1 [M+H]+. Anal. Calcu-
lated for C22H23NO3S: C, 69.26; H, 6.08; N, 3.67%. Found:
C, 69.32; H, 6.14; N, 3.56%.
1
833, 796. H NMR (400 MHz, DMSO-d6): δ 8.25 (d, J =
7.9 Hz, 1H), 7.88 (s, 1H), 7.22–7.17 (m, 4H), 6.92-6.89 (m,
4H), 3.76 (m, 7H), 1.84 (m, 2H), 1.73(m, 2H), 1.62–1.59
(m, 1H), 1.29–1.27 (m, 4H), 1.14–1.12 (m, 1H). 13C NMR
(100 MHz, DMSO-d6): δ 160.0, 159.2, 158.4, 140.9, 137.6,
137.1, 130.7, 130.1, 129.8, 127.9, 125.7, 114.3, 114.0, 55.2,
55.1, 48.4, 32.5, 25.3, 24.9. ESI-MS m/z Calculated 421.2.
Found: 422.2 [M + H]+. Anal. Calculated for C25H27NO3S:
C, 71.23; H, 6.46; N, 3.32%. Found: C, 71.46; H, 6.38; N,
3.28%.
2.2d3 N-butyl-4,5-bis(4-methoxyphenyl)thiophene-2-
carboxamide (5c): Prepared from 3 and n-butyl amine.
Off-white powder. M.p. 53–55◦C. IR (KBr) cm−1: 3303, 2.2d7 N-cycloheptyl-4,5-bis(4-methoxyphenyl)
2931, 2835, 1609, 1556, 1248, 1032, 829, 795. 1H NMR (400 thiophene-2-carboxamide (5g): Prepared from 3 and
MHz, DMSO-d6): δ 8.48 (t, J = 5.6 Hz, 1H), 7.82 (s, 1H), cycloheptyl amine. White powder, M.p. 212–214◦C. IR
7.22–7.17 (m, 4H), 6.93–6.89 (m, 4H), 3.76 (s, 3H), 3.75 (s, (KBr) cm−1: 3243, 2925, 2854, 1609, 1562, 1244, 1037,
1
3H), 3.27 (quartet, J = 6.8 Hz, 2H), 1.54 (quintet, J = 6.9 Hz, 830, 795. H NMR (400 MHz, DMSO-d6): δ 8.29 (d, J =
2H), 1.38 (sextet, J = 7.4 Hz, 2H ), 0.92 (t, J = 7.3 Hz, 3H). 7.9 Hz, 1H), 7.89 (s, 1H), 7.21–7.17 (m, 4H), 6.92–6.89 (m,
13C NMR (100MHz, DMSO-d6): δ 160.8, 159.2, 158.4, 4H), 3.95–3.91 (m, 1H), 3.76 (s, 3H), 3.75 (s, 3H), 1.89–1.85
140.9, 137.4, 137.1, 130.6, 130.1, 129.8, 127.9, 125.6, (m, 2H), 1.67–1.63 (m, 2H), 1.58–1.51 (m, 5H), 1.49–1.39
114.3, 114.0, 55.2, 55.1, 40.2, 31.3, 19.6, 13.7. ESI-MS m/z (m, 3H). 13C NMR (100 MHz, DMSO-d6): δ 159.8, 159.2,
Calculated 395.1. Found: 396.1 [M + H]+. Anal. Calculated 158.4, 140.9, 137.7, 137.1, 130.7, 130.1, 129.8, 128.0, 125.7,

4,5-diarylthiophene-2-carboxamide derivatives
114.3, 114.0, 55.2, 55.1, 50.5, 34.4, 27.9, 23.9. ESI-MS m/z 129.9, 127.7, 125.4, 122.1, 115.5, 114.4, 114.1, 55.3, 55.2.
Calculated 435.2. Found: 436.2 [M + H]+. Anal. Calculated ESI-MS m/z Calculated 493.0. Found: 492.0 [79MBr− H]−;
for C26H29NO3S: C, 71.69; H, 6.71; N, 3.22%. Found: C, 493.9 [81MBr− H]−. Anal. Calculated for C25H20BrNO3S:
71.66; H, 6.68; N, 3.26%.
C, 60.73; H, 4.08; N, 2.83%. Found: C, 60.87; H, 4.05; N,
2.78%.
2.2d8 4,5-bis(4-methoxyphenyl)-N-phenylthiophene-
2-carboxamide (5h): Prepared from 3 and aniline. Pale
yellow powder, M.p. 158–160◦C. IR (KBr) cm−1: 3308,
2.2d12 N-benzyl-4,5-bis(4-methoxyphenyl)
thiophene-2-carboxamide (5l): Prepared from 3 and
benzyl amine. Yellow powder, M.p. 60–63◦C. IR (KBr)
cm−1: 3306, 2929, 2834, 1624, 1553, 1247, 1030, 829, 795.
1H NMR (400 MHz, DMSO-d6): δ 9.09 (t, 1H, J = 7.3 Hz),
7.91 (s, 1H), 7.35–7.33 (m, 4H), 7.27–7.23 (m, 1H), 7.21–
7.17 (m, 4H), 6.93–6.89 (m, 4H), 4.49 (d, 2H, J = 5.9 Hz),
3.76 (s, 3H), 3.75 (s, 3H). 13C NMR (100MHz, DMSO-d6): δ
160.9, 159.2, 158.5, 141.3, 139.4, 137.2, 136.9, 130.9, 130.1,
129.8, 128.4, 127.9, 127.3, 126.9, 125.6, 114.3, 114.0, 55.2,
55.1, 42.6. ESI-MS m/z Calculated 429.1. Found: 430.1
[M + H]+. Anal. Calculated for C26H23NO3S: C, 72.70; H,
5.40; N, 3.26%. Found: C, 72.60; H, 5.36; N, 3.12%.
1
2930, 2833, 1632, 1551, 1246, 1033, 830, 754. H NMR
(400 MHz, DMSO-d6): δ 10.24 (s, 1H), 8.13 (s, 1H), 7.76
(d, J = 7.8 Hz, 2H), 7.39 (t, J = 7.8 Hz, 2H), 7.26–7.22 (m,
4H), 7.13 (t, J = 7.4 Hz, 1H), 6.95–6.92 (m, 4H), 3.77 (s,
3H), 3.75 (s, 3H). 13C NMR (100 MHz, DMSO-d6): δ 159.7,
159.4, 158.6, 142.3, 138.8, 137.4, 137.1, 131.9, 130.2,
129.9, 128.8, 127.8, 125.5, 123.8, 120.2, 114.4, 114.1, 55.3,
55.2. ESI-MS m/z Calculated 415.1. Found: 416.2 [M +
H]+. Anal. Calculated for C25H21NO3S: C, 72.27; H, 5.09;
N, 3.37%. Found: C, 72.41; H, 5.06; N, 3.34%.
2.2d9 N-(4-fluorophenyl)-4,5-bis(4-methoxyphenyl)
thiophene-2-carboxamide (5i): Prepared from 3 and 4-
fluoroaniline. Off-white powder, M.p. 176–178◦C. IR (KBr)
cm−1: 3312, 2931, 2834, 1632, 1557, 1246, 1032, 830, 795.
1H NMR (400 MHz, DMSO-d6): δ 10.30 (s, 1H), 8.10 (s,
1H), 7.78–7.75 (m, 2H), 7.26–7.19 (m, 6H), 6.95–6.92 (dd,
4H, J = 8.8 Hz & J = 3.1 Hz), 3.77 (s, 6H). 13C NMR
(100 MHz, DMSO-d6): δ 159.6, 159.5, 159.4, 158.6, 157.2,
142.4, 137.4, 136.9, 135.2, 135.1, 131.9, 130.2, 129.9,
127.8, 125.4, 122.1, 122.0, 115.5, 115.3, 114.4, 114.1, 55.3,
55.1. ESI-MS m/z Calculated 433.1. Found: 434.1 [M +
H]+. Anal. Calculated for C25H20FNO3S: C, 69.27; H, 4.65;
N, 3.23%. Found: C, 69.10; H, 4.45; N, 3.12%.
2.2d13 N-(4-fluorobenzyl)-4,5-bis(4-methoxyphenyl)
thiophene-2-carboxamide (5m): Prepared from 3 and
4-fluorobenzyl amine. Yellow powder, M.p. 66–68◦C. IR
(KBr) cm−1: 3307, 2929, 2835, 1625, 1554, 1291, 1032,
1
828, 795. H NMR (400 MHz, DMSO-d6): δ 9.09 (t, J =
5.9 Hz, 1H), 7.89 (s, 1H), 7.39–7.36 (m, 2H), 7.27–7.22
(m, 3H), 7.21–7.15 (m, 3H), 6.94–6.89 (m, 4H), 4.46 (d,
J = 5.9 Hz, 2H), 3.76 (s, 3H), 3.75 (s, 3H). 13C NMR
(100 MHz, DMSO-d6): δ 162.4, 162.3, 160.9, 160.0, 159.2,
158.4, 141.3, 137.2, 136.9, 135.6, 135.5, 131.0, 130.1,
129.7, 129.4, 129.3, 128.9, 128.2, 127.8, 125.5, 125.3,
115.2, 114.9, 114.3, 114.0, 55.2, 55.1, 41.8. ESI-MS m/z
Calculated 447.1. Found: 448.1 [M + H]+. Anal. Calculated
for C26H22FNO3S: C, 69.78; H, 4.96; N, 3.13%. Found: C,
69.46; H, 4.88; N, 3.02%.
2.2d10 N-(4-chlorophenyl)-4,5-bis(4-methoxyphenyl)
thiophene-2-carboxamide (5j): Prepared from 3 and
4-chloroaniline. Pale yellow powder, M.p. 152–154◦C. IR
(KBr) cm−1: 3358, 2931, 2834, 1636, 1582, 1248, 1033,
827, 795. 1H NMR (400 MHz, DMSO-d6): δ 10.36 (s,
1H), 8.11 (s, 1H), 7.79 (d, J = 8.9 Hz, 2H), 7.44 (d, J =
8.8 Hz, 2H), 7.26 (t, J = 8.5 Hz, 4H), 6.95–6.92 (dd, J =
8.8 Hz & J = 2.7 Hz, 4H), 3.77 (s, 3H), 3.75 (s, 3H). 13C
NMR (100MHz, DMSO-d6): δ 159.8, 159.4, 158.6, 142.6,
137.8, 137.5, 136.7, 132.2, 130.2, 129.9, 128.7, 127.7,
127.4, 125.4, 121.7, 114.4, 114.1, 55.3, 55.2. ESI-MS m/z
Calculated 449.0. Found: 448.0 [M − H]−. Anal. Calculated
for C25H20ClNO3S: C, 66.73; H, 4.48; N, 3.11%. Found: C,
67.10; H, 4.25; N, 2.88%.
2.2d14 4,5-bis(4-methoxyphenyl)-N-(4-
(trifluoromethyl)benzyl)thiophene-2-carboxamide (5n):
Prepared from 3 and 4-trifluoromethyl benzyl amine. Pale
brown powder, M.p. 61–63◦C. IR (KBr) cm−1: 3305, 2933,
1
2837, 1622, 1555, 1291, 1033, 829, 795. H NMR (400
MHz, CDCl3): δ 7.59 (d, J = 8.1 Hz, 2H), 7.53 (s, 1H), 7.46
(d, J = 8.1 Hz, 2H), 7.22–7.20 (m, 4H), 6.82–6.79 (m, 4H),
6.55 (t, J = 6.0 Hz, 1H), 4.67 (d, J = 5.9 Hz, 2H), 3.79 (s,
3H), 3.78 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 162.1,
159.6, 158.9, 142.9, 142.3, 137.8, 134.8, 131.5, 130.4,
130.1, 130.0, 129.7, 128.2, 128.0, 125.9, 125.7, 125.6,
125.5, 125.63, 125.4, 122.7, 114.1, 113.9, 55.3, 55.2, 43.4.
ESI-MS m/z Calculated 497.1. Found: 498.1 [M + H]+.
Anal. Calculated for C27H22F3NO3S: C, 65.18; H, 4.46; N,
2.82%. Found: C, 64.88; H, 4.38; N, 3.02%.
2.2d11 N-(4-bromophenyl)-4,5-bis(4-methoxyphenyl)
thiophene-2-carboxamide (5k): Prepared from 3 and
4-bromoaniline. Pale yellow powder, M.p. 170–172◦C. IR
(KBr) cm−1: 3353, 2931, 2834, 1638, 1548, 1248, 1034,
837, 727. 1H NMR (400 MHz, DMSO-d6): δ 10.35 (s, 1H),
8.11 (s, 1H), 7.74 (d, J = 8.9 Hz, 2H), 7.57 (d, J = 8.72 2.2d15 4,5-bis(4-methoxyphenyl)-N-(2-(thiophen-2-
Hz, 2H), 7.26–7.22 (m, 4H), 6.95–6.92 (m, 4H), 3.77 (s, yl)ethyl)thiophene-2-carboxamide (5o): Prepared from
3H), 3.75 (s, 3H). 13C NMR (100MHz, DMSO-d6): δ 159.8, 3 and thiophene-2-ethylamine. Light brown powder, M.p.
159.4, 158.6, 142.6, 138.2, 137.5, 136.7, 132.2, 131.6, 130.2, 137–140◦C. IR (KBr) cm−1: 3349, 2934, 2835, 1626, 1557,

T Shanmuganathan et al.
1
31.4, 19.9, 13.6. ESI-MS m/z Calculated 367.1. Found: z
366.2 [M − H]−. Anal. Calculated for C21H21NO3S: C,
68.64; H, 5.76; N, 3.81%. Found: C, 68.54; H, 5.64; N,
3.90%.
1248, 1029, 832, 793. H NMR (400 MHz, CDCl3): δ 7.44
(s, 1H), 7.23–7.21 (m, 2H), 7.18–7.15 (m, 3H), 6.97–6.95
(m, 1H), 6.88–6.87 (m, 1H), 6.83–6.79 (m, 4H), 6.17 (bs,
1H), 3.79 (s, 6H), 3.74 (quartet, J = 6.4 Hz, 2H), 3.17 (t, J =
6.5 Hz, 2H). 13C NMR (100 MHz, CDCl3): δ 161.9, 159.6,
158.8, 142.4, 141.2, 137.7, 135.4, 131.1, 130.5, 130.1,
128.3, 127.2, 126.0, 125.5, 124.1, 114.1, 113.9, 55.3, 55.2,
41.3, 30.0. ESI-MS m/z Calculated 449.1. Found: 450.1 [M
+ H]+. Anal. Calculated for C25H23NO3S2: C, 66.79; H,
5.16; N, 3.12%. Found: C, 69.32; H, 5.14; N, 3.56%.
2.2e4 N-cyclopropyl-4,5-bis(4-hydroxyphenyl)
thiophene-2-carboxamide (6d): Prepared from 4 and
◦
cyclopropyl amine. Pale yellow powder, M.p. 167–171 C.
IR (KBr) cm−1: 3401, 2925, 2855, 1609, 1549, 1231, 1189,
1
832. H NMR (400 MHz, CDCl3): δ 8.79 (bs, 2H), 7.55 (s,
1H), 7.14–7.12 (m, 2H), 7.08–7.06 (m, 3H), 6.76–6.74 (m,
4H), 2.88 (m, 1H), 0.82–0.81 (m, 2H), 0.65 (m, 2H). 13C
NMR (100 MHz, DMSO-d6): δ 162.7, 158.9, 157.5, 141.9,
137.4, 136.6, 131.4, 130.4, 130.1, 126.5, 123.8, 116.2, 115.9,
23.3, 6.2. ESI-MS m/z Calculated 351.1. Found: 352.1 [M
+ H]+. Anal. Calculated for C20H17NO3S: C, 68.36; H,
4.88; N, 3.99%. Found: C, 68.56; H, 4.66; N, 3.92%.
2.2e General synthetic procedure for the title compounds
4,5-bis(4-hydroxyphenyl)-substituedthiophene-2-carboxamide
(6a–6o): The synthesis was similar to the synthesis of com-
pounds 5a–5o. Using 4,5-bis(4-hydroxyphenyl)thiophene-2-
carboxylic acid(4) and appropriate amine as raw materials,
title compounds 6a–6o were obtained. The reaction timing
and yield of the product are shown in Table 1.
2.2e5 N-cyclopentyl-4,5-bis(4-hydroxyphenyl)
thiophene-2-carboxamide (6e): Prepared from 4 and
cyclopentyl amine. Brown powder, M.p. 216–219◦C. IR
(KBr) cm−1: 3391, 2958, 2869, 1611, 1565, 1261, 1174,
835. 1H NMR (400 MHz, DMSO-d6): δ 9.69 (bs, 1H), 9.51
(bs, 1H), 8.26 (d, J = 7.3 Hz, 1H), 7.84 (s, 1H), 7.10–7.06
(m, 4H), 6.73–6.71 (m, 4H), 4.21–4.14 (m, 1H), 1.91–1.85
(m, 2H), 1.69–1.60 (m, 2H), 1.56–1.49 (m, 4H). 13C NMR
(100 MHz, DMSO-d6): δ 160.6, 157.5, 156.6, 141.1, 137.1,
136.9, 130.8, 130.0, 129.7, 126.5, 124.1, 115.6, 115.3,
50.9, 32.2, 23.6. ESI-MS m/z Calculated 379.1. Found:
380.1 [M + H]+. Anal. Calculated for C22H21NO3S: C,
69.63; H, 5.58; N, 3.69%. Found: C, 69.42; H, 5.62; N,
3.80%.
2.2e1 4,5-bis(4-hydroxyphenyl)-N-propylthiophene-
2-carboxamide (6a): Prepared from 4 and n-propyl
amine. Off-white powder, M.p. 193–195◦C. IR (KBr) cm−1
:
1
3391, 2926, 1651, 1549, 1262, 1173, 832. H NMR (400
MHz, DMSO-d6): δ 8.92 (s, 1H), 8.72 (s, 1H), 8.52 (t, J
= 7.3 Hz, 1H), 7.71 (s, 1H), 7.24–7.18 (m, 4H), 6.90–6.76
(m, 4H), 3.26 (m, 2H), 1.59(m, 2H), 0.88 (t, J = 7.3 Hz, 3H).
13C NMR (100 MHz, CDCl3+ DMSO-d6): δ 161.1, 159.3,
158.6, 140.8, 137.6, 137.4, 130.8, 130.2, 129.8, 127.8, 125.6,
114.2, 114.1, 40.8, 22.6, 11.5. ESI-MS m/z Calculated
353.1. Found: 354.1 [M + H]+. Anal. Calculated for
C20H19NO3S: C, 67.97; H, 5.42; N, 3.96%. Found: C, 67.86;
H, 5.62; N, 3.90%.
2.2e6 N-cyclohexyl-4,5-bis(4-hydroxyphenyl)
2.2e2 4,5-bis(4-hydroxyphenyl)-N-isopropylthiophene-
2-carboxamide (6b): Prepared from 4 and isopropyl
thiophene-2-carboxamide (6f): Prepared from 4 and
cyclohexyl amine. Brown powder, M.p. 162–164◦C. IR
(KBr) cm−1: 3367, 2930, 2854, 1609, 1555, 1258, 1172,
833. 1H NMR (400 MHz, DMSO-d6): δ 9.71 (bs, 1H), 9.53
(bs, 1H), 8.20 (d, J = 8.0 Hz, 1H), 7.83 (s, 1H), 7.09-7.05
(m, 4H), 6.73-6.70 (m, 4H), 3.71 (m, 1H), 1.83 (m, 2H),
1.73 (m, 2H), 1.62-1.59 (m, 1H), 1.29-1.23 (m, 4H), 1.13-
1.11 (m, 1H). 13C NMR (100MHz, DMSO-d6): δ 160.1,
157.5, 156.6, 141.1, 137.1, 136.9, 130.7, 130.1, 129.8, 126.5,
124.2, 115.6, 115.3, 48.4, 32.6, 25.3, 24.9. ESI-MS m/z
Calculated 393.1. Found: 394.1 [M + H]+. Anal. Calculated
for C23H23NO3S: C, 70.20; H, 5.89; N, 3.56%. Found: C,
69.88; H, 5.68; N, 3.60%.
amine. Off-white powder, M.p. 226–228◦C. IR (KBr) cm−1
:
1
3359, 2933, 1611, 1557, 1265, 1173, 832. H NMR (400
MHz, DMSO-d6): δ 9.69 (s, 1H), 9.51 (s, 1H), 8.22 (d, J =
7.8 Hz, 1H), 7.82 (s, 1H), 7.10-7.05 (m, 4H), 6.73-6.70 (m,
4H), 4.09–4.01 (m, 1H), 1.17 (d, J = 6.6 Hz, 6H). 13C NMR
(100 MHz, DMSO-d6): δ 160.6, 157.9, 157.0, 141.5, 137.5,
137.4, 131.1, 130.5, 130.2, 126.9, 124.6, 116.0, 115.8, 41.5,
22.9. ESI-MS m/z Calculated 353.1. Found: 354.1 [M +
H]+. Anal. Calculated for C20H19NO3S: C, 67.97; H, 5.42;
N, 3.96%. Found: C, 67.92; H, 5.56; N, 3.90%.
2.2e3 N-butyl-4,5-bis(4-hydroxyphenyl)thiophene-2-
carboxamide (6c): Prepared from 4 and n-butyl amine.
Brown powder, M.p. 256–259◦C. IR (KBr) cm−1: 3360, 2.2e7 N-cycloheptyl-4,5-bis(4-hydroxyphenyl)
1
2929, 1608, 1563, 1252, 1177, 834. H NMR (400 MHz, thiophene-2-carboxamide (6g): Prepared from 4 and
CDCl3+ DMSO-d6): δ 8.94 (s, 1H), 8.77 (s, 1H), 7.45 (m, cycloheptyl amine. Brown powder, M.p. 150–152◦C. IR
1H), 7.09 (s, 1H), 6.98–6.89 (m, 4H), 6.61–6.58 (m, 4H), (KBr) cm−1: 3370, 2927, 2855, 1609, 1554, 1260, 1172,
3.25 (quartet, J = 6.9 Hz, 2H), 1.45–1.39 (m, 2H), 1.27– 833. 1H NMR (400 MHz, DMSO-d6): δ 9.71 (bs, 1H), 9.55
1.21 (m, 2H), 0.80 (t, J = 7.2 Hz, 3H). 13C NMR (100 MHz, (bs, 1H), 8.24 (d, J = 9.0 Hz, 1H), 7.84 (s, 1H), 7.09–7.05
CDCl3+ DMSO-d6): δ 161.9, 157.1, 156.2, 141.9, 137.2, (m, 4H), 6.72–6.70 (m, 4H), 3.96–3.87 (m, 1H), 1.88–1.81
135.7, 130.8, 130.1, 129.8, 126.9, 124.6, 115.4, 115.2, 39.4, (m, 2H), 1.69–1.63 (m, 2H), 1.57–1.54 (m, 6H), 1.52–1.44

4,5-diarylthiophene-2-carboxamide derivatives
(m, 2H). 13C NMR (100 MHz, DMSO-d6): δ 159.9, 157.5,
156.6, 141.1, 137.1, 137.0, 130.7, 130.1, 129.8, 126.5,
124.2, 115.6, 115.3, 50.4, 34.4, 27.9, 23.9. ESI-MS m/z
Calculated 407.1. Found: 408.2 [M + H]+. Anal. Calculated
for C24H25NO3S C, 70.73; H, 6.18; N, 3.44%. Found: C,
70.56; H, 6.20; N, 3.26%.
(100 MHz, DMSO-d6): δ 159.8, 157.7, 156.7, 142.8, 138.2,
137.4, 136.0, 132.2, 131.5, 130.1, 129.8, 126.2, 123.8,
121.9, 115.7, 115.4. ESI-MS m/z Calculated 465.0. Found:
464.0 [79MBr− H]−; 466.0 [81MBr− H]−. Anal. Calculated
for C23H16BrNO3S: C, 59.24; H, 3.46; N, 3.00%. Found: C,
59.20; H, 3.48; N, 2.88%.
2.2e12 N-benzyl-4,5-bis(4-hydroxyphenyl)thiophene-
2-carboxamide (6l): Prepared from 4 and benzyl amine.
2.2e8 4,5-bis(4-hydroxyphenyl)-N-phenylthiophene-
2-carboxamide (6h): Prepared from 4 and aniline. Pale
green powder, M.p. 236–240◦C. IR (KBr) cm−1: 3376,
Pale green powder, M.p. 170–172◦C. IR (KBr) cm−1
:
1
1
3308, 2927, 1609, 1556, 1269, 1172, 834. H NMR (400
MHz, DMSO-d6): δ 9.04 (t, J = 5.9 Hz, 1H), 7.84 (s, 1H),
7.36–7.29 (m, 4H), 7.27–7.24 (m, 1H), 7.10–7.04 (m, 4H),
6.73–6.69 (m, 4H), 4.47 (d, J = 5.9 Hz, 2H). 13C NMR
(100 MHz, DMSO-d6): δ 161.1, 157.6, 156.7, 141.5, 139.5,
137.2, 131.1, 130.1, 129.7, 128.4, 127.3, 126.9, 115.7,
115.4, 42.5. ESI-MS m/z Calculated 401.1. Found: 400.1
[M − H]−. Anal. Calculated for C24H19NO3S: C, 71.80; H,
4.77; N, 3.49%. Found: C, 71.68; H, 4.88; N, 3.48%.
2959, 1629, 1547, 1252, 1180, 833. H NMR (400 MHz,
DMSO-d6): δ 10.17 (s, 1H), 9.75 (s, 1H), 9.56 (s, 1H), 8.07
(s, 1H), 7.75 (d, J = 7.8 Hz, 2H), 7.38 (t, J = 7.6 Hz, 2H),
7.14–7.09 (m, 5H), 6.75–6.73 (m, 4H). 13C NMR (100 MHz,
CDCl3+DMSO-d6): δ 160.5, 157.3, 156.4, 143.2, 138.7,
137.5, 136.2, 131.8, 130.2, 129.9, 128.6, 127.1, 124.7,
123.7, 120.3, 115.6, 115.4. ESI-MS m/z Calculated 387.1.
Found: 388.1 [M+H]+. Anal. Calculated for C23H17NO3S:
C, 71.30; H, 4.42; N, 3.62%. Found: C, 71.60; H, 4.48; N,
3.56%.
2.2e13 N-(4-fluorobenzyl)-4,5-bis(4-hydroxyphenyl)
thiophene-2-carboxamide (6m): Prepared from 4 and 4-
fluorobenzyl amine. Light brown powder, M.p. 248–250◦C.
IR (KBr) cm−1: 3349, 2927, 1608, 1560, 1226, 1169, 833.
1H NMR (400 MHz, CDCl3+ DMSO-d6): δ 8.99 (m, 1H)
8.81 (m, 1H), 7.65 (m, 1H), 7.39–7.38 (m, 1H), 7.36–7.33
(m, 2H), 7.14 (d, J = 8.6 Hz, 2H), 7.08 (d, J = 8.6 Hz, 2H),
7.03 (t, J = 8.71 Hz, 2H), 6.76–6.73 (d, J = 8.6 Hz, 4H),
4.56 (d, J = 5.9 Hz, 2H). 13C NMR (100 MHz, CDCl3+
DMSO-d6): δ 163.2, 162.2, 160.8, 157.4, 156.4, 142.7,
137.6, 135.4, 135.3, 134.7, 131.4, 130.3, 129.9, 129.6, 129.5,
127.2, 124.8, 115.6, 115.5, 115.4, 115.1, 42.9. ESI-MS m/z
Calculated 419.1. Found: 420.1 [M + H]+. Anal. Calculated
for C24H18FNO3S: C, 68.72; H, 4.33; N, 3.34%. Found: C,
68.68; H, 4.48; N, 3.34%.
2.2e9 N-(4-fluorophenyl)-4,5-bis(4-hydroxyphenyl)
thiophene-2-carboxamide (6i): Prepared from 4 and
4-fluoroaniline. Pale green powder, M.p. 226–233◦C. IR
1
(KBr) cm−1: 3379, 2926, 1636, 1509, 1223, 1172, 831. H
NMR (400 MHz, DMSO-d6): δ 10.24 (s, 1H), 9.77 (s, 1H),
9.57 (s, 1H), 8.04 (s, 1H), 7.77–7.74 (m, 2H), 7.23–7.18
(m, 2H), 7.14–7.09 (m, 4H) 6.76–6.73 (m, 4H). 13C NMR
(100 MHz, DMSO-d6): δ 160.1, 158.1, 157.6, 157.2, 142.9,
137.9, 136.7, 135.6, 135.6, 132.4, 130.5, 130.4, 130.3,
126.7, 124.4, 122.5, 122.4, 116.1, 115.9, 115.7. ESI-MS m/z
Calculated 405.1. Found: 406.1 [M + H]+. Anal. Calculated
for C23H16FNO3S: C, 68.13; H, 3.98; N, 3.45%. Found: C,
68.22; H, 3.88; N, 3.48%.
2.2e10 N-(4-chlorophenyl)-4,5-bis(4-hydroxyphenyl)
thiophene-2-carboxamide (6j): Prepared from 4 and
4-chloroaniline. Pale green powder, M.p. 170–174◦C. IR
2.2e14 4,5-bis(4-hydroxyphenyl)-N-(4-(trifluoromethyl)
benzyl)thiophene-2-carboxamide (6n): Prepared from
4 and 4-trifluoromethyl benzyl amine. Light brown powder,
M.p. 185–189◦C. IR (KBr) cm−1: 3361, 2928, 1627, 1556,
1256, 1176, 834. 1H NMR (400 MHz, CDCl3+ DMSO-d6):
δ 9.07 (bs, 1H), 8.9 (bs, 1H), 8.16 (bs, 1H), 7.69 (s, 1H), 7.58
(d, J = 8.2 Hz, 2H), 7.51 (d, J = 8.1 Hz, 2H), 7.14−7.12
(m, 2H), 7.09–7.07 (m, 2H), 6.76–6.73 (m, 4H), 4.64 (d, J
= 5.9 Hz, 2H). 13C NMR (100 MHz, CDCl3+ DMSO-d6):
δ 162.4, 157.4, 156.4, 143.3, 142.8, 137.6, 135.3, 131.6,
130.3, 129.9, 129.3, 128.9, 127.9, 127.2, 125.5, 125.3,
125.2, 124.8, 122.8, 115.6, 115.5, 43.1. ESI-MS m/z Cal-
culated 469.1. Found: 470.0 [M + H]+. Anal. Calculated
for C25H18F3NO3S: C, 63.96; H, 3.86; N, 2.98%. Found: C,
63.88; H, 3.68; N, 3.00%.
1
(KBr) cm−1: 3400, 2929, 1638, 1515, 1230, 1170, 831. H
NMR (400 MHz, DMSO-d6): δ 10.30 (s, 1H), 9.77 (s, 1H),
9.57 (s, 1H), 8.06 (s, 1H), 7.79–7.77 (m, 2H), 7.43–7.41
(m, 2H), 7.15–7.10 (m, 4H) 6.76–6.72 (m, 4H). 13C NMR
(100 MHz, DMSO-d6): δ 160.3, 158.2, 157.2, 143.2, 138.3,
137.9, 136.5, 132.6, 130.6, 130.5, 130.3, 130.2, 129.1,
126.7, 124.3, 122.1, 116.7, 115.9. ESI-MS m/z Calcu-
lated 421.1. Found: 422.1 [M + H]+. Anal. Calculated for
C23H16ClNO3S: C, 65.48; H, 3.82; N, 3.32%. Found: C,
65.62; H, 3.68; N, 3.88%.
2.2e11 N-(4-bromophenyl)-4,5-bis(4-hydroxyphenyl)
thiophene-2-carboxamide (6k): Prepared from 4 and
4-bromoaniline. Pale green powder, M.p. 165–169◦C. IR
1
(KBr) cm−1: 3401, 2928, 1636, 1515, 1231, 1170, 832. H 2.2e15 4,5-bis(4-hydroxyphenyl)-N-(2-(thiophen-2-yl)
NMR (400 MHz, DMSO-d6): δ 10.29 (s, 1H), 9.77 (s, 1H), ethyl)thiophene-2-carboxamide (6o): Prepared from 4
9.57 (s, 1H), 8.07 (s, 1H), 7.74–7.71 (m, 2H), 7.56–7.54 and thiophene-2-ethyl amine. Off white powder, M.p. 247–
(m, 2H), 7.15–7.10 (m, 4H) 6.76–6.72 (m, 4H). 13C NMR 249◦C. IR (KBr) cm−1: 3368, 2928, 1610, 1557, 1246, 1169,

T Shanmuganathan et al.
1
at co-crystallised ligand centre and grid energy calculations
were carried out. AutoDock docking calculation was done
using default parameters and twenty docked conformations
were generated for each compound. The energy of the bind-
ing interactions was estimated using genetic algorithm. The
outputs were exported to PyMOL and visualised the binding
modes and interactions of the compounds with amino acid
residues in the active sites.26
831. H NMR (400 MHz, DMSO-d6): δ 9.71 (s, 1H), 9.53
(s, 1H), 8.64 (t, J = 5.6 Hz, 1H), 7.76 (s, 1H), 7.35–7.33
(m, 1H), 7.10–7.08 (m, 2H), 7.07–7.06 (m, 2H), 6.97–6.96 (m,
1H), 6.92–6.91 (m, 1H), 6.73–6.70 (m, 4H), 3.51 (quartet,
J = 7.2 Hz, 2H) 3.08 (t, J = 7.2 Hz, 2H). 13C NMR (100
MHz, CDCl3+ DMSO-d6): δ 162.1, 157.2, 156.3, 141.4,
137.4, 135.3, 131.1, 130.2, 129.9, 127.1, 126.8, 125.1,
124.7, 123.6, 115.5, 115.3, 41.2, 29.7. ESI-MS m/z Cal-
culated 421.1. Found: 422.1 [M + H]+. Anal. Calculated
for C23H19NO3S2: C, 65.53; H, 4.54; N, 3.32%. Found: C,
65.72; H, 4.56; N, 3.40%.
3. Results and Discussion
2.3 In vitro anti-inflammatory activity
(Anti-denaturation assay)
3.1 Chemistry
In the present work, we synthesized a novel series of 4,
5-diarylthiophene-2-carboxamide derivatives which is
shown in Scheme 1. The first step in the Scheme 1 is the
Vilsmeier reaction27,28 of desoxyanisoin 1 with dime-
thylformamide (DMF) and phosphorous oxychloride
(POCl3) to give compound 2 in 78% yield after recrys-
tallization from ethanol.20 The obtained compound 2
was condensed and cyclized with 2-mercaptoacetic acid
(thioglycolic acid) in the presence of potassium hydrox-
ide to afford compound 329 in 71% yield. We studied the
demethylation of compound 3 with several reactants in
different reaction conditions. Treatment of compound 3
with aqueous hydrobromic acid30 or hydrobromic acid
in acetic acid,31,32 gave no product. Reaction of com-
pound 3 with boron tribromide33 (4 and 6 equivalents)
in methylene chloride gave the product in 50% yield.
Treatment of compound 3 with aluminium chloride in
dichloromethane34 or benzene or toluene35 in reflux
condition gave compound 4 in 30–50% yield. In our
present procedure, it was found that 4 mole of alumin-
ium chloride in chlorobenzene36 at 95–105◦C over 3 h
under stirring is vital for the demethylation of com-
pound 3 to get compound 4 in good yield (88%). The
obtained compound 4 did not require any further purifi-
cation.
The in vitro anti-inflammatory activity of the synthesized
compounds was studied using bovine serum albumin denat-
uration method.21,22 In brief, increasing concentrations of
the test or reference compound were incubated with 0.5%
w/v of bovine serum albumin at 37◦C for 20 min and the
temperature was increased to keep the samples at 57◦C for
30 min. After cooling to room temperature, the turbidity was
measured using UV-Visible spectrophotometer at 660 nm
following addition of phosphate buffered saline. The con-
trol represents 100% protein denaturation. The results were
compared with reference drug Diclofenac sodium. The per-
centage inhibition of protein denaturation was calculated by
using the following formula.
Percentage Inhibition = 100
-[(optical density of test solution
-optical density of product control)
÷(optical density of test control)] × 100
2.4 Molecular docking studies
In silico molecular docking simulation was executed using
the AutoDock Tools (ADT) version 1.5.6 and AutoDock ver-
sion 4.2.5.1 docking program.23,24 Three dimensional struc-
ture of COX-2 receptor was obtained from the Protein Data
Bank (PDB ID: 1PXX).25 The co-crystallized ligand in the
Reaction of 4,5-diarylthiophene-2-carboxylic acid 3
1PXX structure was removed. The water molecules present and 4 with various substituted amine derivatives (alkyl,
with the crystal were deleted, the polar hydrogen atoms were
added, lower occupancy residue structures were deleted, and
any incomplete side chains were replaced using the ADT.
Gasteiger charges were added to each atom and merged
the non-polar hydrogen atoms to the protein structure. The
hydrogen bond distance between donor and acceptor atoms
was defined as 1.9 Å with a tolerance of 0.5 Å, and the thresh-
old for acceptor– hydrogen–donor angle was set to not less
than 120◦. Then, the structures were saved in PDBQT file
format for further studies in ADT. Around the binding site of
co-crystallised ligand, a grid box with the dimension of 60 ×
60 × 60 Å3 with 0.375 Å spacing centred on 27.131, 24.348,
cycloalkyl, aryl, aryl alkyl and heterocyclic alkyl) in the
presence of 2-(1H-Benzotriazole-1-yl)-1,1,3,3-tetrame-
thyluronium tetrafluoroborate (TBTU)37 39 dimethyl-
aminopyridine in acetonitrile at 25–30◦C afforded the
amides in 72–95% yields. The amides were crystallized
from ethanol. The compounds were confirmed by NMR,
IR, Mass spectra and X-ray single crystallography.
The structure of the synthesized compound (5j) was
confirmed by various spectral techniques such as NMR,
Mass and IR data. IR spectrum of the compound (5j)
revealed that the band at around 3360–3300 cm−1 cor-
14.747 was created using ADT. The centre of the box was set responds to the –NH stretching of the amide group. The

4,5-diarylthiophene-2-carboxamide derivatives
CH3
O
CH3
O
O
Cl
i
ii
O
O
O
CH3
CH3
1
2
CH3
O
HO
O
O
iii
OH
OH
S
S
O
HO
4
3
CH3
iv
iv
RO
O
NHR1
S
RO
5a-5o R = CH3
6a-6o R = H
R1= Alkyl, Cycloalkyl, Aryl,
Aryl alkyl & Heterocyclic alkyl
Scheme 1. Synthesis of 4,5-diarylthiophene-2-carboxamide derivatives.
Reagents and conditions: i) DMF and POCl3, at 70–75◦C for 4 h; ii)
2-mercapto acetic acid, KOH, methanol and water, at reflux for 4 h; iii)
AlCl3 and chlorobenzene, at 95–105◦C for 3 h; iv) TBTU, dimethylaminopy-
ridine, acetonitrile and R1NH2 (R1 = Alkyl, Cycloalkyl, Aryl, Aryl alkyl and
Heterocyclic alkyl), at 25–30◦C for 3-7 h.
band at around ∼1636 cm−1 corresponds to the car-
signals at δ 114.1 and at δ 114.4 ppm correspond to
1
the four phenyl ring carbons, ortho to the methoxy
group. Mass spectrum acquired in positive ionization
ESI mode showed the signal at 450.3 Da which corre-
sponds to [35MCl+ H]+, confirmed the molecular mass
of the compound. The chlorine isotopic peak [37MCl+
H]+ was also observed at 452.0 Da. In addition to
the above spectral evidences discussed, the structure of
synthesized compound (5j) was further confirmed with
single-crystal X-ray diffraction. The crystal data was
bonyl group of the amide moiety. The H NMR spec-
trum recorded in DMSO-d6showed twenty protons. The
six protons observed at δ 3.75 and at δ 3.76 ppm cor-
respond to the methoxy protons. The singlet observed
at δ 8.11 ppm corresponds to the thiophene ring proton.
The singlet at δ 10.36 ppm corresponds to –NH proton
of the amide group. The 13C NMR spectrum recorded
in DMSO-d6 showed nineteen signals, in which the
signals observed at δ 55.2 ppm and at δ 55.3 ppm
confirmed the presence of methoxy carbons. The two deposited at CCDC, and the CCDC No. is 1400968.

T Shanmuganathan et al.
Similarly, the structure of 5b, 5l and 5o were assigned acid to amide with p-halo substituted phenyl moiety
(6h–k) resulted in analogues having anti-inflammatory
activity comparable to the standard drug. In addition,
amidic substitution with benzyl (6l), fluoro benzyl
(6m), p-trifluoromethyl benzyl (6n) or thiophene-2ethyl
(6o) group resulted in less active analogues. Introduc-
tion of cyclopropyl (6d) or cyclopentyl (6e) or cyclo-
hexyl (6f) or cycloheptyl(6g) amidic group resulted in
compounds that are less active than the standard drug.
Similar is the case with substitution of alkyl amide
group 6a–c where there is a substantial loss of activity.
Interestingly, p-methoxy groups of the diaryl moi-
ety compound 5 showed a marginal increase in anti-
inflammatory activity in comparison to 6. However, an
increase in potency is not seen with the correspond-
ing p-methoxy analogues of 4,5-diaryl thiophenes-2-
carboxamide having p-halo substituted phenyl amidic
by single-crystal X-ray diffraction, deposited at CCDC
and the CCDC No. are 1064110, 1404546 and 1406561
respectively. The ORTEP diagram of above crystal
compounds as shown in Figures 2a–d.
3.2 Biological Evaluation
3.2a In vitro Anti-inflammatory activity: The anti-
inflammatory activity of the novel substituted 4,5-dia-
rylthiophene-2-carboxamide derivatives were evaluated
using inhibition of bovine serum albumin denaturation
method and compared with standard drug diclofenac
sodium. The results are summarized in Table 2.
Most of the compounds exhibited anti-inflammatory
activity that is comparable to diclofenac sodium. The
free acid 4 is less potent, however derivatisation of the
Figure 2. (a) ORTEP diagram of compound 5j [N-(4-chlorophenyl)-4, 5-bis (4-methoxyphenyl) thiophene-2-carboxamide
(CCDC 1400968)]; (b) ORTEP diagram of compound 5b [N-isopropyl-4,5-bis(4-methoxyphenyl)thiophene-2-carboxamide
(CCDC 1064110)]; (c) ORTEP diagram of compound 5l [N-benzyl-4,5-bis(4-methoxyphenyl)thiophene-2-carboxamide
(CCDC 1404546)]; (d) ORTEP diagram of compound 5o [4,5-bis(4-methoxyphenyl)-N-(2-(thiophen-2-yl)ethyl)thiophene-2-
carboxamide (CCDC 1406561)].

4,5-diarylthiophene-2-carboxamide derivatives
Table 2. Activity (% inhibition) and Free energy of binding (FEB) of all the synthesised compounds.
Activity (% inhibition of protein denaturation)
FEBa (kcal/mol)b
Entry
Compounds
50 μg/mL
100 μg/mL
400 μg/mL
800 μg/mL
COX-2 (PDBID:1PXX)
1
2
3
4
5
6
7
8
3
14.98
7.86
16.42
8.98
20.55
16.46
24.98
17.86
21.89
23.78
34.34
29.61
26.36
20.09
28.36
24.31
24.37
17.62
22.34
17.31
16.47
15.46
16.48
11.31
14.31
15.72
16.79
18.84
22.26
21.17
24.98
26.85
15.62
16.15
17.01
12.65
50.64
53.01
24.12
30.48
28.48
29.24
43.64
48.58
48.79
48.88
56.96
53.05
56.36
42.14
46.93
44.48
37.26
28.13
24.48
23.11
22.24
22.65
28.98
33.29
30.33
44.82
48.69
47.06
50.84
24.46
26.43
22.29
25.94
65.38
41.45
39.26
46.81
40.96
45.13
58.95
62.28
63.12
64.51
73.46
75.28
74.03
69.78
68.38
66.52
46.89
30.33
38.77
36.66
37.26
33.72
38.16
42.46
44.21
65.85
68.88
70.72
69.48
42.41
46.85
40.19
35.71
75.38
−8.54
−9.63
5a
5b
5c
5d
5e
5f
5g
5h
5i
−9.9
−10.37
21.09
18.96
25.75
11.62
17.24
16.32
17.22
16.22
19.44
16.61
16.22
16.22
9.84
7.52
8.86
9.11
13.74
7.31
16.05
12.01
14.28
10.71
13.17
15.88
10.22
11.28
12.08
7.04
−9.75
−11.06
−11.53
−9.83
9
−11.11
−11.06
−10.94
−11.11
−11.16
−11.08
−10.81
−11.63
−7.96
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
5j
5k
5l
5m
5n
5o
4
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
−9.36
−9.6
−9.87
−9.39
−10.61
−11.16
−9.64
−10.88
−10.72
−11.17
−11.67
−10.82
−10.62
−10.4
6m
6n
6o
Std
−10.8
29.24
−8.15
Std = Diclofenac sodium,aFree Energy of Binding, bCalculated using Autodock 4.
group 5h–k. In contrast to 6l-n, there is an enhance- amides of the 4,5-diarylthiophene-2-carboxamide has
ment of activity with the methoxy analogues of 4, poor activity whereas the p-substituted benzyl or phenyl
5-diarylthiophene-2-carboxamide with benzyl (5l) or or cycloalkyl amide group has optimal activity. This
p-fluoro substituted benzyl group (5m) or p-trifluo- indicates the requirement of bulkier substitution which
romethyl benzyl (5n) which is comparable to the would interact with active sites of the biological target.
standard drug. The presence of p-methoxy group in In conclusion, this study has identified a number of
the case of 4,5-diarylthiophene-2-carboxamide with amidic substituents to the thiophene ring and also
cyclopropyl (5d) or cyclopentyl (5e) or cyclohexyl the methoxy substitution to the diaryl ring which
(5f) or cycloheptyl (5g) amidic group dramatically is crucial for the anti-inflammatory property of 4,5-
improved the anti-inflammatory activity in comparison diarylthiophene-2-carboxamide.
to corresponding p-OH substituted 4,5-diarylthiophene-
2-carboxamide. As observed with 6a–c, substitution
with alkyl amide to methoxy 4,5-diarylthiophene-2-
carboxamide resulted in less potent analogues.
3.3 Molecular docking studies
Together, these results clearly suggest that p-
methoxy group of 4,5-diarylthiophene-2-carboxamide
derivatives is advantageous in improving or retain-
ing the anti-inflammatory spectrum. In general, alkyl
To rationalize the pharmacological results, the binding
mode of the potent inhibitors was investigated using
AutoDock Tools (ADT) version 1.5.6 and AutoDock
version 4.2.5.1 docking program.23,24 In the present

T Shanmuganathan et al.
investigation, we docked these compounds to cyclo- In silico molecular docking studies of synthesised
oxygenase-2 (COX-2) receptor (PDB ID: 1PXX)25 compounds with 1PXX receptor revealed that all the
crystal structure to gain insights into the possible docked compounds bind with the receptor and exhibits
reasons for the anti-inflammatory activity. The co- free energy of binding value from −9.36 to −11.67
crystallised ligand was extracted from the complex and Kcal/mole (Table 2). Notably, all the synthesised com-
submitted for one-ligand run calculation to verify the pounds showed higher binding affinity than the stan-
reproducibility of the docking calculation. Root-mean- dard drug diclofenac sodium. Particularly aryl, aryl
square deviation (RMSD) value of 0.58 Å of docked alkyl, heterocyclic derivatives of 4,5-diarylthiophene-
co-crystallised ligand with bound X-ray conformation 2-carboxamide showed higher binding affinity than the
for 1PXX, suggesting this method is valid enough to be standard drug. All the synthesised compounds bind in
used for docking studies of other compounds (Figure the active site and the simulated conformation exhibits
3A).
various interactions with different amino acids by
(a)
(b)
(c)
Figure 3. Molecular docking simulation with COX-2 receptor (1PXX).
(a) Method validation using crystallised and docked ligand diclofenac;
(b) Docking simulation of all the compounds in the active site; (c) Docking
simulation of the highest binding energy compound 6k.

4,5-diarylthiophene-2-carboxamide derivatives
IR and Mass data (Figures S1–S124) are given in the sup-
porting information. Supplementary Information is available
at www.ias.ac.in/chemsci.
non-covalent interactions such as hydrophobic, hydro-
philic, π−π interaction and hydrogen bonding (Figure
3B).
Interestingly, among all the compounds docked,
compound 6k exhibits very high binding with 1PXX
receptor (Figure 3C) and forms three hydrogen bonds
Acknowledgements
with three amino acids, namely, LEU-352, MET-522 The authors are thankful to the management of Orchid
and SER-530, which resulted in the binding energy of Pharma Limited, Chennai 600 119, India and Ramakrishna
−11.67 kcal/mol. As shown in Figure 3C, in the com- Mission Vivekananda College, Chennai 600 004, India for
pound 6k, one of the O–H interacts with the C=O of providing the required facilities.
LEU-352 and forms a hydrogen bond with the bond
length of 1.9 Å. Another O–H interacts with the C=O
of MET-522 and forms a hydrogen bond with the bond
length of 2.4 Å. Amide C=O interacts with the O–
H of SER-530 and forms a hydrogen bond with the
bond length of 2.0 Å. Furthermore, bromine forms polar
interaction with the N–H of ARG-120 and O–H of
TYR-355 amino acid. Also, amide N–H forms polar
interaction with the N–H of LEU-531. In addition to
the polar interactions, phenyl rings exhibit hydropho-
bic interaction with the VAL-116, LEU-352, VAL-523,
GLY-526, ALA-527, LEU-531 and LEU-350. Also,
phenyl rings exhibit π−π interaction with the phenyl
rings of the PHE-381, TYR-385 and PHE-518.
References
1. Vane J R 1971 Inhibition of prostaglandin synthesis as
a mechanism of action for aspirin-like drugs Nature 231
232
2. Reitz D B and Isakson P C 1995 Cyclooxygenase-2
inhibitors Curr. Pharm. Design 1 211
3. Gans K R, Galbraith W, Roman R J, Haber S B, Kerr J S,
Schmidt W K, Smith C, Hewes W E and Ackerman N R
1990 Anti-inflammatory and safety profile of DuP 697,
a novel orally effective prostaglandin synthesis inhibitor
J. Pharmacol. Exp. Ther. 254 180
4. Vane J R, Bakhle Y S and Botting R M 1998 Cyclooxy-
genases 1 and 2 Annu. Rev. Pharmacol. 38 97
5. Masferrer J L, Seibert K, Zweifel B and Needleman P
1992 Endogenous glucocorticoids regulate an inducible
cyclooxygenase enzyme P. Natl. Acad. Sci. U.S.A. 89
3917
6. Masferrer J L, Reddy S T, Zweifel B S, Seibert K,
Needleman P, Gilbert R S and Herschman H R 1994 In
vivo glucocorticoids regulate cyclooxygenase-2 but not
cyclooxygenase-1 in peritoneal macrophages J. Phar-
macol. Exp. Ther. 270 1340
7. Tanaka A, Motoyama Y and Takasugi H 1994 Studies
on Anti-platelet Agents. IV. A Series of 2-Substituted
4, 5-Bis(4-methoxyphenyl)pyrimidines as Novel Anti-
platelet Agents Chem. Pharm. Bull. 42 1828
8. Tseng C H, Chen Y L, Chung K Y, Cheng C M, Wang
C H and Tzeng C C 2009 Synthesis and antiproliferative
evaluation of 6-arylindeno[1,2-c]quinoline derivatives
Bioorgan. Med. Chem. 17 7465
9. Gadad A K, Palkar M B, Anand K, Noolvi M N,
Boreddy T S and Wagwade 2008 Synthesis and bio-
logical evaluation of 2-trifluoromethyl/sulfonamido-5,6-
diaryl substituted imidazo[2,1-b]-1,3,4-thiadiazoles: A
novel class of cyclooxygenase-2 inhibitors Bioorgan.
Med. Chem. 16 276
10. Palkar M B, Noolvi M N, Maddi V S, Ghatole M
and Nargund L G 2011 Synthesis, spectral studies
and biological evaluation of a novel series of 2-
substituted-5,6-diarylsubstituted imidazo(2,1-b)-1,3,4-
thiadiazole derivatives as possible anti-tubercular agents
Med. Chem. Res. 21 1313
4. Conclusions
In summary, we have synthesized a series of novel 4,5-
diarylthiophene-2-carboxamide compounds containing
alkyl, cycloalkyl, aryl, aryl alkyl, and heterocyclic alkyl
moieties. These compounds were characterized and
evaluated for their in vitro anti-inflammatory activi-
ties. Among the novel compounds, the inhibition of
bovine serum albumin denaturation assay revealed that
the aryl and aryl alkyl derivatives of 4,5-diarylthio-
phene-2-carboxamide showed anti-inflammatory activ-
ity comparable to the standard drug diclofenac sodium,
whereas alkyl and cycloalkyl amide derivatives showed
less activity. From the docking studies, aryl, aryl alkyl
and heterocyclic derivatives of 4,5-diarylthiophene-
2-carboxamide showed higher binding energy than
the standard drug. Particularly, the compound (6k) N-
(4-bromophenyl)-4,5-bis(4-hydroxyphenyl)thiophene-
2-carboxamide showed high free energy binding of
−11.67 kcal/mol. Further studies are in progress to
improve the biological activities of 4,5-diarylthio-
phene-2-carboxamide derivatives.
Supplementary Information (SI)
11. Malik J K, Soni H and Singhai A K 2013 Synthesis,
characterization and evaluation for antifungal activity
of substituted diaryl imidazo [2, 1, b]-benzothiazole J.
Pharm. Res. 7 39
The characterization of the compounds 2, 3, 4, 5a, 5b, 5c,
5d, 5e, 5f, 5g, 5h, 5i, 5j, 5k, 5l, 5m, 5n, 5o, 6b, 6c, 6d, 6e,
6f, 6g, 6h, 6i, 6k, 6l, 6m, 6n and6o using 1HNMR, 13CNMR,

T Shanmuganathan et al.
Diclofenac bound to the cyclooxygenase active site of
12. Krohn K, Kulikowski K and Leclercq G 1989
Diethylstilbestrol-linked cytotoxic agents Synthesis and
binding affinity for estrogen receptors J. Med. Chem. 32
1532
13. Klose W and Schwarz K 1982 Nichtsteroidale entzün-
dungshemmer. 13 Bis-(4-methoxyphenyl)-2-arylthio-
pyrimidine J. Heterocycl. Chem. 19 1165
14. Szmuszkovicz J, Glenn E M, Heinzelman R V,
Hester J B Jr. and Youngdale G A 1966 Synthesis
and anti-inflammatory activity of 2,3-bis(p-methoxy-
phenyl)indole and related compounds J. Med. Chem. 9
527
15. Thomas E W, Nishizawa E E, Zimmermann D C
and Williams D J 1985 Synthesis and platelet aggre-
gation inhibitory activity of 4,5-bis(substituted)-1,2,3-
thiadiazoles J. Med. Chem. 28 442
16. Marnett L J and Kalgutkar A S 1999 Cyclooxygenase
2 inhibitors: discovery, selectivity and the future Trends
Pharmacol. Sci. 20 465
17. Zarghi A, Rao P N P and Knaus E E 2007 Design
and synthesis of new rofecoxib analogs as selec-
tive cyclooxygenase-2 (COX-2) inhibitors: Replace-
ment of the methanesulfonyl pharmacophore by a
N-acetylsulfonamido bioisostere J. Pharm. Pharm. Sci.
10 159
18. Pinto D J P, Batt D G, Pitts W J, Petraitis J J, Orwat M J,
Wang S, Jetter J W, Sherk S R, Houghton G C, Copeland
R A, Covington M B, Trzaskos J M and Magolda R L
1999 Terphenyl cyclooxygenase-2 (COX-2) inhibitors:
Optimization of the central ring and o-biphenyl analogs
Bioorgan. Med. Chem. Lett. 9 919
19. Pinto D J P, Copeland R A, Covington M B, Pitts
W J, Batt D G, Orwat M J, Lam G N, Joshi A,
Chan Y-C, Wang S, Trzaskos J M, Magolda R L
and Kornhauser D M 1996 Chemistry and pharma-
cokinetics of diarylthiophenes and terphenyls as selec-
tive COX-2 inhibitors Bioorgan. Med. Chem. Lett. 6
2907
COX-2. doi: 10.2210/pdb1pxx/pdb
26. Lill M A and Danielson M L 2010 Computer-aided drug
design platform using PyMOL J. Comput. Aided Mol.
Des. 25 13
27. Tordjman C, Sauveur F, Droual M, Briss S, Andre N,
Bellot I, Deschamps C and Wierzbicki M 2003 Synthe-
sis of the butanamide derivative S 19812, a new dual
inhibitor of cyclooxygenase and lipoxygenase pathways
Arzneimittel-Forschung 53 774
28. Wang Z, Yang Q, Bai Z, Sun J, Jiang X, Song H, Wu Y
and Zhang W 2015 Synthesis and biological evaluation
of 2,3-diarylthiophene analogues of combretastatin A-4
MedChemComm 6 971
29. Kvitko I Y 1969 Synthesis of derivatives of thieno[2,3-
c]pyrazole and thieno[2,3-d]thiazoline Chem.
cycl. Comp. 5 567
30. Paolo C and Flavio V 1984 New derivatives of
1,2,3,4-tetrahydronaphthalene, process for their prepa-
ration and associated pharmaceutical compositions
G.B. Patent 2123410A
31. Long L and Burger A 1941 Structural models of cortin
compounds in the naphthalene series J. Org. Chem. 6
852
32. Przybyl A K, Flippen-Anderson J L, Jacobson A E
and Rice K C 2003 Practical and High-Yield Synthe-
ses of Dihydromorphine from Tetrahydrothebaine and
Efficient Syntheses of (8S)-8-Bromomorphide J. Org.
Chem. 68 2010
33. McOmie F W and West D W 1969 3,3’-Dihydro-
xybiphenyl Organic Syntheses 49 50
34. Negi A, Chattopadhyay S, Srivastava S and Bhattacharya
A 2006 Process for regioselective demethylation of
p-methoxy group in phenolic ester and diaryl ketone
moieties U.S. Patent 0052463
35. Chiesi P, Ventura P, Servadio V, Del C M, De F R
and Amari G 1995 A process for the preparation of 5,6-
dihydroxy-2-amino-1,2,3,4-tetrahydronaphthalene deri-
vatives WO Patent 029 147A1
36. Kobayashi K, Shimizu H, Sasaki A and Suginome
H 1993 Photoinduced molecular transformations. 140.
New one-step general synthesis of naphtho[2,3-b]furan-
4,9-diones and their 2,3-dihydro derivatives by the
regioselective [3 + 2] photoaddition of 2-hydroxy-
1,4-naphthoquinones with various alkynes and alkenes:
Application of the photoaddition to a two-step synthesis
of maturinone J. Org. Chem. 58 4614
Hetero-
20. Wierzbicki M, Sauveur F, Bonnet J and Tordjman
C 1998 Thiophene compounds U.S. Patent 5705525
21. Mizushima Y and Kobayashi M 1968 Interaction of anti-
inflammatory drugs with serum proteins, especially with
some biologically active proteins J. Pharm. Pharmacol.
20 169
22. Rajadurai R, Padmanabhan R and Ananthan S 2013
Synthesis and biological evaluation of diamide deriva-
tives of (S)-BINOL and biphenyl as potential anti-
inflammatory/anti-arthritic agents Med. Chem. Res. 22
4164
37. Al-Tel T H, Al-Qawasmeh R A and Zaarour R 2011
Design, synthesis and in vitro antimicrobial evalua-
tion of novel Imidazo[1,2-a]pyridine and imidazo[2,1-b]
[1,3] benzothiazole motifs European J. Med. Chem. 46
1874
38. Kolczewski S, Roche O, Steward L, Wichmann J and
Woltering T 2010 6-substituted benzoxazines as 5-ht-5a
receptor antagonists WO Patent 026 110A3
23. Sanner M F 1999 Python: A programming language for
software integration and development J. Mol. Graph.
Model 17 57
24. Morris G M, Huey R, Lindstrom W, Sanner M F,
Belew R K, Goodsell D S and Olson A J 2009
AutoDock4 and AutoDockTools4: Automated docking 39. Balalaie S, Mahdidoust M and Eshaghi-Najafabadi
with selective receptor flexibility J. Comput. Chem. 30
2785
25. Kiefer J R, Rowlinson S W, Prusakiewicz J J, Pawlitz J
L, Kozak K R, Kalgutkar A S, Stallings W C, Marnett
L J and Kurumbail R G 2003 Crystal structure of
R 2007 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyl-
uronium tetrafluoroborate as an efficient coupling
reagent for the amidation and phenylhydrazation of
carboxylic acids at room temperature J. Iran. Chem. Soc.
4 364