Potassium tert-butoxide catalyzed synthesis and characterization of novel 3-aryl-3-(phenylthio)-1-(thiophen-3-yl)propan-1-one derivatives

Article abstract of DOI:10.1002/cjoc.201180484

A series of thiophenyl-containing 3-thiophene derivatives (4a-4i) were prepared via the reaction of chalcone-analogua compounds (3a-3i) and thiophenol in the presence of catalytic amount of KOBu-t in CH₂Cl₂ with moderate to high yiel

Full text of DOI:10.1002/cjoc.201180484

FULL PAPER
DOI: 10.1002/cjoc.201180484
Potassium tert-Butoxide Catalyzed Synthesis and Characteri-
zation of Novel 3-Aryl-3-(phenylthio)-1-(thiophen-3-yl)-
propan-1-one Derivatives
Budak, Yakup
Department of Chemistry, Faculty of Arts and Sciences, Gaziosmanpasa University, 60250, Tokat, Turkey
A series of thiophenyl-containing 3-thiophene derivatives (4a—4i) were prepared via the reaction of chal-
cone-analogua compounds (3a—3i) and thiophenol in the presence of catalytic amount of KOBu-t in CH2Cl2 with
moderate to high yields. The mechanistic pathway of the reaction was explained by the Michael-type addition of
thiophenol to chalcone derivatives (3a—3i).
Keywords 1-(thiophen-3-yl)ethanone, Michael addition, potassiumtert-butoxide, chalcone, catalysis
InBr3,[17] Zn(ClO4)2•6H2O,[18] Hf(OTf)3,[19] Bi(NO3)3,[20]
Bi(OTf)3,[21] Cu(BF4)2.[22] Most of the methods have
some disadvantages like long reaction times, high reac-
tion temperature, dry or stringent reaction conditions,
complex work-up procedures, and moderate yields. In
this study, we reported the potassium tert-butoxide
catalyzed addition of thiophenol to chalcones under
mild conditions in short reaction time, high yield and at
room temperature.
Introduction
α,β-Unsaturated ketones, especially 1,3-diarylprop-
2-en-1-ones, are commonly called as chalcones. Chal-
cones, either natural or synthetic are known to exhibit
various biological activities[1] such as antioxidant,[2]
anti-inflammatory,[3] antimalaria,[4] antileishmanial,[5]
anticancer[6] and antitumor.[7] In addition, chalcones are
very important compounds as a Michael acceptor in
organic syntheses. The Michael reaction since its dis-
covery in 1889 is one of the most important reactions in
organic chemistry.[8] It is well known that conjugate
addition to α,β-unsaturated carbonyl compounds is a
useful strategy for the construction of carbon-carbon
and carbon-sulfur bonds.[9-11] The carbon-sulfur bond
formation by 1,4-addition of thiols to α,β-unsaturated
carbonyl compounds has versatile application in chem-
istry and biology as it plays critical roles in the biosyn-
thesis, synthesis of bioactive compounds, protection of
the olefinic double bond of conjugated enones, and
generation of β-acylvinyl cation homoenolate anion
equivalents.[12-14] The Michael addition of thiols to elec-
tron deficient alkenes is a very useful process for mak-
ing carbon-sulfur bond. This addition to chalcone de-
rivatives is very interesting and challenging as it is less
facile compared to the addition to aliphatic acyclic
enones and thus it is not always satisfactory with the
conventional reagents used for general 1,4-addition.[10]
Numerous methods have been reported in literature
regarding the nucleophilic activation of thiols for the
desired transformation catalyzed by various organic and
inorganic bases.[15] On the other hand, these reactions
were also investigated using solid acids such as
HClO4-SiO2,[16] and different Lewis acids, such as
Results and Discussion
Firstly, the chalcone derivatives 3a—3i were syn-
thesized employing the traditional method reported in
literature.[23-29] As shown in Scheme 1 and Table 1, a
series of 9 chalcone derivatives 3a—3i were prepared
using the base catalyst. The reaction of 1-(thiophen-3-
Scheme 1
O
O
O
R
NaOH/EtOH
H
+
R
r.t., 3 - 4 h
S
S
3a - 3i
2a - 2i
1
SPh
R
O
Thiophenol
CH2Cl2/KOBu-t
r.t., 2 - 3 h
S
4a - 4i
(a) R = Ph, (b) R = p-Cl-C6H4, (c) R = p-Br-C6H4,
(d) R = p-CH3-C6H4, (e) R = p-OCH3-C6H4,
(f) R = m-Br-C6H4, (g) R = m-CH3-C6H4,
(h) R = o-OCH3-C6H4, (i) R = 2-thiophene (C4H3S)
*
E-mail: ybudak@gop.edu.tr
Received January 23, 2011; accepted September 9, 2011.
Chin. J. Chem. 2012, 30, 341—344
© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
341

Budak
FULL PAPER
Table 1 Synthesized compounds 4a—4i
results are in agreement with the proposed structures.
The syntheses of chalcone-like compounds contain-
ing thiophenol unit (4a—4i) were performed by a
base-catalyzed additon of thiophenol to compounds
3a—3i.[24] In this synthesis, firstly, various bases
(NaOH, KOH, Na2CO3, K2CO3 and KOt-Bu) were
tested as catalyst in different solvents (EtOH, MeOH,
CHCl3, CH2Cl2, etc.). Good results were obtained using
the catalytic amount of KOt-Bu in CH2Cl2 as a solvent.
The reaction of chalcone-like compounds 3a—3i with
thiophenol in the presence of a catalytic amount of
KOt-Bu in CH2Cl2 at room temperature afforded the
compounds 4a—4i in yields of 73%—93% (Table1).
The crude products were purified by filtration on a
short silica gel column and recrystallized from CH2Cl2/
n-hexane (1∶5). While the compounds 4a, 4b, 4c, 4d
and 4f were obtained as pure colorless crystals, the oth-
ers were liquid. In this series, compounds (4a—4i) are
unknown according to our literature survey.
Entry
Product Time/h m.p./℃ Yield/%
O
S
2.5 90—91
2.5 87—88
2.5 97—98
2.5 57—58
93
93
88
94
82
4a
S
O
O
S
S
4b
4c
4d
4e
Cl
Br
S
S
The structures of compounds (4a—4i) were deter-
mined on the basis of spectral data (1H NMR, 13C NMR,
IR and elemental analysis).
O
S
In summary, nine novel thiophenyl-containing
3-thiophene derivatives (4a—4i) were easily prepared
by the reaction of compounds (3a—3i) with thiophenol
in the presence of catalytic amount of KOt-Bu in
CH2CI2 with good yields and the mild reaction condi-
tions (room temperature and simple operation). Potas-
siumtert-butoxide (KOt-Bu) was found to be an effi-
cient catalyst for Michael-type addition of thiophenol to
chalcone derivatives.
CH3
S
O
S
Colorless
2.5
liquid
OCH3
S
O
O
O
S
S
S
2.5
2.5
88-89
85
81
4f
Experimental
S
Br
General
1-(Thiophene-3-yl)ethanone (1) and aldehyde de-
rivatives 2a—2i are commercially available (Merck).
All reagents were dried and distilled by standard proce-
dures. Melting points were measured on an Electro-
thermal 9100 apparatus. IR spectra (KBr or liquid) were
recorded on a Jasco FT/IR-430 spectrometer. 1H and 13C
NMR spectra were recorded on a Bruker Avance III 400
instrument. As internal standards served TMS (δ 0.00)
Yellowish
liquid
4g
S
CH3
1
for H NMR and CDCl3 (δ 77.0) for 13C NMR spec-
Yellowish
liquid
2.5
2.5
86
73
4h
4i
troscopy, J values are given in Hz. The multiplicities of
1
the signals in the H NMR spectra are abbreviated by s
H3CO
S
S
(singlet), d (doublet), t (triplet), q (quarted), m (multi-
plet), br (broad) and combinations thereof. Elemental
analyses were obtained from a LECO CHNS 932 Ele-
mental Analyzer.
Cherry
liquid
O
S
S
General procedure for preparation of thiophen-
chalcone derivatives 4a—4i[24]
A solution of chalcone derivatives (1 mmol)
(3a—3i)[24] and thiophenol (1 mmol) in CH2CI2 (5 mL)
was stirred at room temperature for 2—3 h in the pres-
ence of a catalytic amount of KOt-Bu. After the reaction
was completed, the reaction mixture was extracted with
yl)ethanone (1) with benzaldehyde derivatives 2a—2i in
ethanolic NaOH gave the chalcone derivatives 3a—3i in
high yields (93%—99%) (Sheme 1, Table 1). The struc-
tures of chalcones (3a—3i) were established on the ba-
sis of spectral data and compared to literature data. The
342
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© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2012, 30, 341—344

Synthesis of Novel 3-Aryl-3-(phenylthio)-1-(thiophen-3-yl)propan-1-one Derivatives
diethyl ether (15 mL×3). The extract was washed with
H2O, and dried (Na2SO4). The solvent was evaporated
(45 ℃, 20 mmHg). After the crude product was fil-
trated on a short silica gel column, pure product was
obtained by crystallized from n-hexane and CH2Cl2
(5∶1), yield 73%—93%.
7.44 (d, J＝7.6 Hz, 1H), 7.36—7.35 (m, 1H),
7.29—7.21 (m, 5H), 6.80 (d, J＝8.8 Hz, 2H), 6.94 (d,
J＝8.6 Hz, 2H), 4.93 (t, J＝6.4 Hz, 1H), 3.76 (s, 3H,
OCH3), 3.54 (d, J＝6.4 Hz, 2H); 13C NMR (CDCl3, 100
MHz) δ: 191.4, 158.8, 142.1, 134.4, 133.1, 132.6, 132.2,
128.9 (2C), 127.5, 126.9, 126.5, 113.9, 55.2, 47.6, 46.1;
IR (KBr) ν: 3100, 3056, 2927, 2832, 1671, 1509, 1436,
3-Phenyl-3-(phenylthio)-1-(thiophen-3-yl)propan-
1-one (4a) Colorless crystals (n-hexane∶CH2Cl2, 5∶
－
1
1249, 1029, 1072, 825, 736, 688 cm . Anal. calcd for
C20H18O2S2: C 67.76, H 5.12, S 18.09; found C 67.69, H
5.17, S 18.15.
1
1), yield 93%; m.p. 90—91 ℃; H NMR (CDCl3, 400
MHz) δ: 8.00—7.99 (m, 1H), 7.49 (d, J＝5.2 Hz, 1H),
7.45—7.44 (m, 1H), 7.36—7.33 (m, 4H), 7.29—7.23
(m, 7H), 4.95 (t, J＝6.4 Hz, 1H), 3.54 (d, J＝6.4 Hz,
1H); 13C NMR (CDCl3, 100 MHz) δ: 191.2, 142.1,
141.1, 132.7, 132.2, 130.7, 129.0, 128.4, 127.8, 127.6,
127.4, 126.8, 126.5, 48.2, 46.0; IR (KBr) ν: 3104, 3056,
3025, 1671, 1509, 1405, 1232, 1072, 794, 736, 692
3-(3-Bromophenyl)-3-(phenylthio)-1-(thiophen-3-
yl)propan-1-one (4f) Colorless crystals (n-hexane∶
1
CH2Cl2, 5∶1), yield 85%; m.p. 88—89 ℃; H NMR
(CDCl3, 400 MHz) δ: 8.02—8.01 (m, 1H), 7.68 (d, J＝
4.8 Hz, 1H), 7.54 (d, J＝8 Hz, 1H), 7.67 (d, J＝5.1 Hz,
1H), 7.50—7.48 (m, 1H), 7.33—7.30 (m, 3H),
7.26—7.23 (m, 3H), 7.11 (t, J＝7.6 Hz, 1H), 4.86 (t,
J＝6.4 Hz, 1H), 3.50 (d, J＝6.4 Hz, 2H); 13C NMR (100
MHz, CDCl3) δ: 190.7, 143.6, 133.08, 132.4, 130.7,
130.0, 129.0, 127.9, 127.4, 127.2, 126.8, 126.6, 126.4,
124.4, 122.5, 47.7, 45.6; IR (KBr) ν: 3102, 3052, 2896,
1662, 1602, 1506, 1409, 1311, 1226, 1176, 779, 690,
－
1
cm . Anal. calcd for C19H16OS2: C 70.33, H 4.97, S
19.77; found C 70.43, H 4.84, S 19.95.
3-(4-Chlorophenyl)-3-(phenylthio)-1-(thiophen-3-
yl)propan-1-one (4b) Colorless crystals (n-hexane∶
1
CH2Cl2, 5∶1), yield 93%; m.p. 87—88 ℃; H NMR
(CDCl3, 400 MHz) δ: 8.01—8.00 (m, 1H), 7.49 (d, J＝
4.8 Hz, 1H), 7.34—7.31 (m, 4H), 7.26—7.21 (m, 6H),
4.90 (t, J＝6.4 Hz, 1H), 3.48 (d, J＝6.4 Hz, 2H), 13C
NMR (CDCl3, 100 MHz) δ: 190.9, 141.9, 139.8, 133.7,
133.2, 133.0, 132.3, 129.2, 129.0, 128.6, 127.8, 126,8,
126.6, 47.6, 45.7; IR (KBr) ν: 3102, 1673, 1506, 1405,
－
1
570 cm . Anal. calcd for C19H15BrOS2: C 56.58, H
3.75, S 15.90; found C 56.65, H 3.80, S 15.83.
3-(Phenylthio)-1-(thiophen-3-yl)-3-m-tolylpro-
pan-1-one (4g) Yellowish liquid, yield 81%; 1H NMR
(CDCl3, 400 MHz) δ: 7.99—7.97 (m, 1H), 7.82 (d, J＝
15,6 Hz, 1H), 7.70 (d, J＝6,4 Hz, 1H), 7.50—7.44 (m,
2H), 7.40—7.35 (m, 2H), 7.28—7.24 (m, 3H), 7.16 (d,
J＝5.6 Hz, 2H), 4.93 (t, J＝6.4 Hz, 1H), 3.56 (d, J＝6.4
Hz, 2H), 2.31 (s, 3H, CH3); 13C NMR (CDCl3, 100 MHz)
δ: 191.3, 142.09, 141.0, 138.1, 134.4, 132.6, 132.3,
131.4, 128.9, 128.6, 128.4, 128.3, 126.9, 126.5, 124.8,
48.1, 46.0, 21.5; IR (CHCl3) ν: 3100, 3052, 2854, 1656,
1596, 1506, 1409, 1240, 1174, 1029, 981, 779, 736, 700,
－
1
1234, 1091, 1012, 823, 796, 690, 617, 547 cm . Anal.
calcd for C19H15ClOS2: C 63.58, H 4.21, S 17.87; found
C 63.65, H 4.29, S 17.94.
3-(4-Bromophenyl)-3-(phenylthio)-1-(thiophen-3-
yl)propan-1-one (4c) Colorless crystals (n-hexane∶
1
CH2Cl2, 5∶1), yield 88%; m..p. 97—98 ℃; H NMR
(CDCl3, 400 MHz) δ: 8.00—7.99 (m, 1H), 7.56 (d, J＝
8.8 Hz, 1H), 7.51—7.48 (m, 1H), 7.37 (d, J＝8.4 Hz,
2H), 7.34—7.28 (m, 3H), 7.19—7.02 (m, 4H), 4.88 (t,
J＝6.4 Hz, 1H), 3.50 (d, J＝6.4 Hz, 2H); 13C NMR
(CDCl3, 100 MHz) δ: 190.8, 141.9, 140.3, 133.6, 132.9,
132.3, 131.6, 129.5, 129.0, 127.8, 127.2, 126.8, 121.2,
47.6, 45.6; IR (KBr) ν: 3102, 2896, 2846, 1673, 1506,
1486, 1230, 1172, 1072, 1008, 792, 736, 690, 647, 547
－
1
638 cm . Anal. calcd for C20H18OS2: C 70.97, H 5.36,
S 18.95; found C 70.91, H 5.42, S 18.97.
3-(2-Methoxyphenyl)-3-(phenylthio)-1-(thiophen-
3-yl) propan-1-one (4h) Yellowish liquid, yield 86%;
1H NMR (CDCl3, 400 MHz) δ: 8.01—7.98 (m, 1H),
7.51 (d, J ＝ 4.8 Hz, 1H), 7.37—7.34 (m, 3H),
7.28—7.19 (m, 5H), 6.92—6.87 (m, 2H), 5.37 (t, J＝6.4
Hz, 1H), 3.81 (s, 3H, OCH3), 3.55 (d, J＝6.4 Hz, 2H);
13C NMR (CDCl3, 100 MHz) δ: 191.6, 156.6, 142.2,
135.1, 132.3, 132,1, 129.3, 129.1, 128.6, 128.1, 127.2,
127.0, 126.3, 120.7, 111.0, 55.6, 45.4, 42.2; IR (CHCl3)
ν: 3102, 2998, 2834, 1673, 1579, 1506, 1475, 1432,
－
1
cm . Anal. calcd for C19H15BrOS2: C 56.58, H 3.75, S
15.90; found C 56.71, H 3.71, S 15.87.
3-Phenyl-1-(thiophen-3-yl)-3-p-tolylpropan-1-one
(4d) Colorless crystals (n-hexane∶CH2Cl2, 5∶1),
1
yield 94%; m.p. 57—58 ℃; H NMR (CDCl3, 400
MHz) δ: 7.99—7.96 (m, 1H), 7.49—7.48 (m, 1H),
7.36—7.34 (m, 2H), 7.29—7.20 (m, 6H), 7.07 (d, J＝8
Hz, 2H), 4.91 (t, J＝6.4 Hz, 1H), 3.54 (d, J＝6.4 Hz,
4H), 2.30 (s, 3H, CH3); 13C NMR (CDCl3, 100 MHz) δ:
191.3, 142.1, 138.0, 137.1, 132.5, 132.2, 129.2, 128.8,
127.9, 127.6, 127.4, 126.9, 126.4, 47.8, 46.0, 21.1; IR
(KBr) ν: 3102, 3052, 2919, 1673, 1509, 1413, 1234,
－
1
1322, 1245, 1024, 736, 686, 590 cm . Anal. calcd for
C20H18O2S2: C 67.76, H 5.12, S 18.09; found C 67.86, H
5.04, S 18.19.
3-(Phenylthio)-3-(thiophen-2-yl)-1-(thiophen-3-
1
yl)propan-1-one (4i) Cherry liquid, yield 73%; H
NMR (CDCl3, 400 MHz) δ: 8.03—8.02 (m, 1H), 7.52 (d,
J＝5.2 Hz, 1H), 7.42—7.37 (m, 3H), 7.30—7.26 (m,
4H), 7.16 (d, J＝4.8 Hz, 1H), 6.85—6.82 (m, 1H), 5.24
(t, J＝6.4 Hz, 1H), 3.54 (d, J＝6.4 Hz, 2H); 13C NMR
(CDCl3, 100 MHz) δ: 190.7, 145.3, 142.0, 136.5, 133.0,
132.5, 129.0, 128.0, 127.9, 126.7, 126.5, 125.6, 124.6,
－
1
1020, 900, 788, 686 cm . Anal. calcd for C20H18OS2: C
70.97, H 5.36, S 18.95; found C 70.89, H 5.42, S 19.05.
3-(4-Methoxyphenyl)-3-(phenylthio)-1-(thiophen-
3-yl) propan-1-one (4e) Colorless liquid, yield 82%;
1H NMR (CDCl3, 400 MHz) δ: 7.98—7.97 (m, 1H),
Chin. J. Chem. 2012, 30, 341—344
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343

Budak
FULL PAPER
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1587, 1513, 1409, 1265, 1234, 1172, 1076, 1027, 788,
－
1
736, 701, 586 cm . Anal. calcd for C17H14OS3: C 61.78,
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The authors are indebted to the Department of
Chemistry (Gaziosmapasa University) and Scientific
Research Projects Commission of Gaziosmanpasa Uni-
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