An environmentally benign water promoted catalyst free highly efficient, one-pot synthesis of 2-imino-4-thiazolidinone

Article abstract of DOI:10.1002/jhet.1812

A practical and efficient protocol has been developed for the synthesis of 2-imino-4-thiazolidinone through a unique one pot three-component reaction of variety of amines, isothiocyanate and ethylbromoacetate in water. The method is free of catalyst and o

Full text of DOI:10.1002/jhet.1812

Month 2014
An Environmentally Benign Water Promoted Catalyst Free Highly
Efficient, One-pot Synthesis of 2-Imino-4-thiazolidinone
a
a
a
b
*
Umesh B. Kosurkar, Tulshiram L. Dadmal, Ravindra M. Kumbhare, and Balasubramanian Sridhar
aFluoroorganic Division, Indian Institute of Chemical Technology, CSIR, Hyderabad 500 607, India
bLaboratory of X-ray Crystallography, Indian Institute of Chemical Technology, CSIR, Hyderabad 500 607, India
*
E-mail: rakumbhare@yahoo.com
Received June 8, 2012
DOI 10.1002/jhet.1812
Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
A practical and efficient protocol has been developed for the synthesis of 2-imino-4-thiazolidinone through a
unique one pot three-component reaction of variety of amines, isothiocyanate and ethylbromoacetate in water.
The method is free of catalyst and other toxic solvents, has shorter reaction times, high-yielding, effortlessness
in isolation of product, making it more eco-friendly process, and suitable for large scale operation.
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
lesser yield. Yella et al. [18] have also reported the synthesis
of these compounds but in two steps, that is, first synthesis of
thiourea followed by synthesis of iminothiazolidinone. The
efficient synthetic method to prepare 2-imino-4-thiazolidi-
none, in particular with green solvent and different substitu-
tion patterns on each of the nitrogen atoms is still lacking.
Therefore, the development of simple, convenient, and
environmentally benign approaches for the synthesis of
2-imino-4-thiazolidinone is still desirable. In continuation
of our efforts to develop new synthetic methods for important
organic products [19], herein we report one pot, regio-
selective synthesis of 2-imino-4-thiazolidinone. We recently
have been trying to develop approaches to carry out this
reaction without any catalyst. Fortunately, we revealed that
the one-pot three-component reaction of a various amines,
isothiocyanates, and ethylbromoacetate proceeded smoothly
at room temperature in water as solvent under catalyst-free
condition; and this approach provide access to a wide
range of 2-imino-4-thiazolidinone derivatives in excellent
yields. To the best of our knowledge, there are no existing
precedent protocols for the synthesis of 2-imino-4-thiazoli-
dinone using water as medium through one pot, three-com-
ponent reaction at room temperature.
In recent years, multicomponent reactions (MCRs), have
received considerable attention compared with conventional
multistep methods that involves several bond formations in
one step producing a complex molecule, economically
viable, eco-friendly process, with reduced amount of waste
products and their wide range of applications in pharmaceu-
tical chemistry for generation of structural diversity and
combinatorial libraries for drug discovery [1]. The use of
water as reaction medium is an important challenge for
organic chemist because it is non-flammable, non-toxic,
non-volatile and inexpensive “green solvent”. Recently, water
has been employed as a solvent in many organic reactions [2].
The synthesis of 2-imino-4-thiazolidinone has gained
considerable significance as an important intermediate for
many heterocycles [3] and also demonstrates diverse
biological activities such as tuberculostatic [4], antidiabetic
[5], antihistaminic [6], and antifungal activity [7]. Interest-
ingly, 4-thiazolidinone is an important group of heterocycles
found in numerous natural products and pharmaceuticals
such as Cox inhibition [8], anti-HIV [9], and human chon-
drocyte anti-degenerative [10] properties. Some thiazolidin-
4-one derivatives are known to exhibit diverse bioactivities
such as Ca2+ channel blocker [11], PAF antagonist [12],
cardioprotective [13], and cyclooxygenase inhibitory [14].
Moreover, existing literature reveals that there are several
substituted thiazolidinones derivatives that show potent
anti-inflammatory activity [15] (1, Fig. 1), and compound 2
(Fig. 1) affects the growth of colorectal cancer cells and acts
as diverse integrin avb3 antagonists [16].
RESULT AND DISCUSSION
Initially, we studied the impact of N,N-dimethylformamide
(DMF) on the model reaction between aniline 1a (1mmol),
phenylisothiocyanate 2a (1 mmol), and ethylbromoacetate 3
(1 mmol) (Table 1) at room temperature, reaction proceeded
smoothly affording product 4a in 80% yield. Later on, we
started the optimization of reaction in volume ratio of
DMF-water as solvent at room temperature. We observed
that, upon changing the volume ratio of DMF to water from
2:1 to 1:2, the yield of the product increases from 84 to 90%.
A review of the literature illustrated that the reported
method for the synthesis of 2-imino-4-thiazolidinone [17]
is having some limitations such as harsh reaction conditions,
long reaction times, and using volatile solvents resulting in
© 2014 HeteroCorporation

U. B. Kosurkar, T. L. Dadmal, R. M. Kumbhare, and B. Sridhar
Vol 000
A highly efficient method for the preparation of 2-imino-
4-thiazolidinone has been achieved from both symmetrical
and unsymmetrical thiourea in the absence of base. This
reaction gives regio-selective product for unsymmetrical
thiourea, which is dependent on pKa of amines. Its forma-
tion takes place with amine attached to thiourea having
lower pKa as a part of imino component and amine having
higher pKa contributes to other heterocyclic nitrogen. The
measured pKa of aniline and p-methoxyaniline is 4.63
and 5.34, respectively. Hence, aniline forms a part of imino
component, and p-methoxyaniline contributes to the other
heterocyclic nitrogen in the 2-imino-4-thiazolidinone
skeleton. The structures of all compounds were characterized
by 1H and 13C NMR, IR and mass spectrometry, and elemen-
tal analysis. Proton NMR of product showed doublet at
d = 3.92 ppm (J = 0.8 Hz) corresponding to two protons adja-
cent to sulfur atom, an observation that is also found in the
earlier literature [20]. IR spectra of all compounds show
characteristics peak for carbonyl group in the range of
1627–1646 cmꢀ1. HPLC analysis of the compounds 4c,
4d, 4g, and 4i shows regioisomers in the ratio 63:37,
62:38, 60:40, and 66:34, respectively. To verify the skeletal
structure of product 2-imino-4-thiazolidinone, compound 4a
was selected and characterized by X-ray crystallography
(CCDC 833911) as shown in Figure 2 [21].
Figure 1. Medicinally important iminothiazolidinones.
From the previous result, we found that upon increasing
the water content, yield of the product increases. Hence, we
performed the reaction in clean water, and the resulting
product was obtained in maximum yield (98%). So, water
was selected as the best choice for the reaction.
To realize the efficiency and scope of the reaction for the
synthesis of 2-imino-4-thiazolidinone, ethylbromoacetate
was reacted with various amines and isothiocyanates under
optimized reaction condition (Scheme 1).The results are
displayed in Table 2. As per Table 2, aromatic and aliphatic
amines efficiently react with substituted phenylisothiocya-
nates, experienced by exothermic reaction at room tempera-
ture to afford the in situ formation of thiourea, and followed
by reaction with ethylbromoacetate, resulting in the forma-
tion of product 4.
Table 1
Solvent effect on the reaction.a
NH2
N
O
H2O
rt
Br
N
S=C=N
OEt
S
O
Entry
Solvent
DMF
DMF-H2O (2:1)
DMF-H2O (1:1)
DMF-H2O (1:2)
H2O
Reaction time (min)
Yieldb (%)
1
2
3
4
5
15
15
15
15
15
80
84
86
90
98
aReaction condition: aniline (1 mmol), phenylisothiocyanate (1 mmol), and ethylbromoacetate (1 mmol), room temperature. The reaction was monitored by TLC.
bIsolated yields.
Scheme 1. Synthesis of 2-imino-4-thiazolidinone.
S
R'
R
N
O
H2O
R'
S
N
N
O
R-NH2
Br
S
C
N
OC2H5
N
15 - 20 min, rt
1
3
2
O
4
R
R'
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
An Environmentally Benign Water Promoted Catalyst Free Highly Efficient, One-pot
Synthesis of 2-Imino-4-thiazolidinone
Table 2
Regioselective synthesis of 2-imino-4-thiazolidinone in water as solvent under catalyst free condition.
Entry
R
R0
H
Product (4)
Ratioa
Time (min)
15
Yieldb (%)
98
a
b
4-F
15
96
c
d
e
f
3-CF3
4-Cl
3-CF3
H
63:37
62:38
15
15
15
20
94
95
96
94
g
H
60:40
15
95
h
3-CF3,4-Cl
15
15
94
95
i
H
66:34
(Continued)
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

U. B. Kosurkar, T. L. Dadmal, R. M. Kumbhare, and B. Sridhar
Vol 000
Table 2
(Continued)
Entry
R
R0
Product (4)
Ratioa
Time (min)
15
Yieldb (%)
j
3-CF3
94
k
H
20
93
l
4-OCH3
15
15
94
95
m
4-Cl
n
o
t-Butyl
H
15
20
96
96
3-CF3
aRatio of regioisomers as measured by HPLC analysis.
bIsolated yield after purification.
EXPERIMENTAL
CONCLUSION
All chemicals and reagents were purchased from Aldrich
(Sigma–Aldrich, St. Louis, MO, USA), Lancaster (Alfa Aesar,
Johnson Matthey Company, Ward Hill, MA, USA) or Spectrochem
Pvt. Ltd (Mumbai, India) and were used without further purifica-
tion. Reactions were monitored by TLC, performed on silica gel
glass plates containing 60 GF-254, and visualization on TLC was
achieved by UV light or iodine indicator. 1H and 13C spectra were
recorded on Bruker UXNMR/XWIN-NMR (300 MHz) instru-
ments. Chemical shifts (d) are reported in ppm downfield from
internal TMS standard. IR spectra were recorded on Thermo Nicolet
Nexus 670 FTIR spectrometer. ESI spectra were recorded on Micro
In conclusion, we have developed a novel protocol
of three component reaction for the synthesis of 2-imino-4-
thiazolidinone at room temperature, in less time and in excel-
lent yield. Regioselective formations of 2-imino-4-thiazoli-
dinones were observed from unsymmetrical thiourea.
Different substitution pattern on 2-imino-4-thiazolidinone
does not affect the yield of reaction. Major advantage
is that the reaction is carried out in water as a green
solvent. The procedure is extremely useful in synthetic
and medicinal chemistry.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
An Environmentally Benign Water Promoted Catalyst Free Highly Efficient, One-pot
Synthesis of 2-Imino-4-thiazolidinone
2-(4-Chlorophenylimino)-3-(4-methoxyphenyl)thiazolidin-4-
1
one (4d).
White solid. IR (KBr): 1723, 1643, 1369, 1162. H
NMR (75 MHz, CDCl3): d =3.78 (d, J=0.8Hz, 2ꢁ 2H), 3.83 (s,
3H), 3.94 (s, 3H), 6.76–6.85 (m, 5H), 6.98 (d, J= 8.9 Hz, 2H), 7.18–
7.35 (m, 7H), 7.47 (d, J= 8.5 Hz, 2H). 13C NMR (75 MHz, CDCl3):
d = 32.8, 55.3, 55.4, 114.3, 114.7, 121.9, 122.3, 126.9, 128.9, 129.2,
129.3, 129.5, 129.8, 133.1, 134.7, 140.8, 146.6, 154.3, 155.9, 156.8,
159.7, 171.1, 171.4. ESI–MS [M + H+]: m/z= 333. Anal. Calcd for
C16H13ClN2O2S: C 57.83, H 3.92, N 8.43; Found: C 57.76, H 3.87,
N 8.37.
3-P-tolyl-2-(3-(trifluoromethyl)phenylimino)thiazolidin-4-
one (4e).
White solid. Mp 108–110ꢂC. IR (KBr): 1734,
1627, 1362, 1172. 1H NMR ( 300 MHz, CDCl3): d = 3.84 (s,
3H), 3.96 (d, J = 0.8 Hz, 2H), 6.95–7.09 (m, 3H), 7.16 (s, 1H),
7.24 (d, J = 7.6 Hz, 2H,), 7.33–7.46 (m, 2H). 13C NMR
(75 MHz, CDCl3): d = 32.8, 55.4, 114.7, 118.1, 121.1, 124.2,
126.9, 128.9, 129.6, 131.2, 131.7, 148.5, 156.5, 159.8, 171.3.
ESI–MS [M+ H+]: m/z = 351. Anal. Calcd. For C17H13F3N2OS:
C 58.29, H 3.71, N 8.0; Found: C 58.21, H 3.66, N 7.96.
3-phenyl-2-(3-(trifluoromethyl)phenylimino)thiazolidin-4-
one (4f). White solid. Mp 69–71ꢂC. IR(KBr): 1735, 1632, 1361,
1169. 1H- NMR (75 MHz, CDCl3): d =3.98 (d, J= 0.9 Hz, 2H), 6.86
(d, J = 7.2Hz, 1H), 6.99-7.74 (m, 8H). 13C- NMR (75 MHz, CDCl3):
d = 32.9, 118.1, 121.2, 124.2, 127.9, 129.1, 129.4, 129.7, 131.3,
131.7, 134.4, 148.4, 156.2, 171.1. ESI–MS [M + H+]: m/z = 337.
Anal. Calcd for C16H11F3N2OS: C 57.14, H 3.28, N 8.33; Found:
C 57.08, H 3.22, N 8.26.
Figure 2. ORTEP molecular diagram of 4a with thermal ellipsoid at 30%
probability.
mass, Quattro LC using ESI + software with capillary voltage
3.98 kV and ESI mode positive ion trap detector. HPLC was
performed with spectra system (Shimadzu, Kyoto, Japan) using
analytical column (water-XterraW, 5 mm, 4.6 ꢁ 250 mm).The flow
was 1 mL/min, with mobile phase of 10 mm ammonium acetate/
acetonitrile = 50:50 (v/v). Melting points were determined with an
Electro thermal melting point apparatus and are uncorrected.
General procedure for the synthesis of 3-phenyl-2-
(phenylimino)thiazolidin-4-one (4a).
A mixture of aniline
3-(3-chloro-4-fluorophenyl)-2-(phenylimino)thiazolidin-4-one
(4g). White solid. IR (KBr): 1719, 1631, 1379, 1170. H NMR
1
(0.093 g, 1 mmol) and phenylisothiocyanate (0.135 g, 1 mmol) was
stirred at room temperature for 5 min; then to this mixture, water
(5 mL) was added. Ethylbromoacetate (0.167 g, 1 mmol) was added
dropwise, and the mixture stirred at room temperature for 10 min.
After completion of reaction monitored by TLC, reaction mixture
extracted with ethyl acetate and saturated NaHCO3. Organic layer
was dried over anhydrous NaSO4 and crystallized from chloroform/
hexane (6:4) to afford the pure product 4a (0.263 g).
(75 MHz, CDCl3): d =3.96 (d, J=0.8Hz, 2ꢁ 2H), 6.69–6.78 (m,
1H), 6.85 (d, J=7.6Hz, 2H), 6.96 (dd, J1 =6.4Hz, J2 =2.6Hz, 1H),
7.02–7.15 (m, 2H), 7.22–7.35 (m, 5H), 7.38–7.55 (m, 5H). 13C
NMR (75 MHz, CDCl3): d = 32.7, 32.8, 116.7, 116.9, 120.5, 120.6,
120.7, 122.9, 124.8, 127.8, 129.1, 129.2, 129.3, 130.5, 134.4,
144.6, 147.5, 156.8, 159.5, 170.9, 171.1. ESI–MS [M + H+]: m/
z=321. Anal. Calcd for C15H10ClFN2OS: C 56.25, H 3.13, N 8.75;
Found: C 56.17, H 3.08, N 8.69.
3-Phenyl-2-(phenylimino)thiazolidin-4-one (4a).
White
solid. Mp 176–178ꢂC. IR (KBr): 1724, 1636, 1371, 1152. 1H NMR
(300 MHz, CDCl3): d =3.95 (d, J= 0.8 Hz, 2H), 6.85 (d, J=7.6Hz,
2H), 7.07 (t, J=7.6Hz, 1H), 7.23–7.55 (m, 7H). 13C NMR
(75 MHz, CDCl3): d = 32.8, 120.8, 124.5, 127.9, 128.9, 129.1,
129.3, 134.6, 148, 154.8, 171.3. ESI–MS [M + H+]: m/z=269.
Anal. Calcd for C15H12N2OS: C 66.91, H 4.70, N 10.41; Found: C
66.87, H 4.67, N 10.37.
2-(4-chloro-3-(trifluoromethyl)phenylimino)-3-(4-methoxy-
phenyl)thiazolidin-4-one (4h).
White solid. Mp 48–50ꢂC. IR
(KBr): 1740, 1646, 1380, 1175. 1H NMR (500MHz, CDCl3):
d = 3.84 (s, 3H), 3.96 (d, J = 0.9 Hz, 2H), 6.98 (d, J = 8.9 Hz, 3H),
7.17–7.28 (m, 3H), 7.42 (d, J = 7.9 Hz, 1H). 13C NMR (75MHz,
CDCl3): d = 32.8, 55.4, 114.8, 120.6, 124.4, 125.3, 126.7, 127.5,
128.7, 128.9, 132.1, 146.8, 157.1, 159.9, 171.2. ESI–MS
[M+ H+]: m/z = 401. Anal. Calcd for C17H12ClF3N2O2S: C 51.0,
H 3.0, N 7.0; Found: C 50.96, H 2.94, N, 6.96.
(Z)-3-(4-fluorophenyl)-2-(4-fluorophenylimino)thiazolidin-4-
one (4b).
White solid. Mp 120–122ꢂC. IR (KBr): 1731, 1642,
1378, 1160. 1H NMR (75 MHz, CDCl3): d =3.88–4.00 (m, 2H),
6.74–6.89 (m, 2H), 6.92–7.07 (m, 2H), 7.11–7.42 (m, 4H). 13C
NMR (75 MHz, CDCl3): d = 32.7, 115.8, 116.6, 122.3, 129.8, 130.4,
143.8, 155.4, 161.6, 164.0, 171.2. ESI–MS [M + H+]: m/z= 305.
Anal. Calcd for C15H10F2N2OS: C 59.21, H 3.29, N 9.21; Found: C
59.16, H 3.24, N 9.17.
(Z)-3-(4-methoxyphenyl)-2-(phenylimino)thiazolidin-4-one
(4i).
White solid. IR (KBr): 1716, 1643, 1368, 1161. 1H
NMR (300 MHz, CDCl3): d = 3.77 (s, 3H), 3.83 (s, 3H), 3.92
(d, J=0.8Hz, 2ꢁ 2H), 6.77–6.88 (m, 6H), 6.94–7.11 (m, 3H),
7.21–7.54 (m, 9H). 13C NMR (75MHz, CDCl3): d = 32.7, 32.8,
55.3, 55.4, 114.3, 114.7, 120.8, 121.9, 124.5, 127.1, 127.9, 129.1,
129.3, 134.7, 141.1, 148.1, 155.2, 156.7, 159.7, 171.4, 171.6.
ESI–MS [M+ H+]: m/z = 299. Anal. Calcd for C16H14N2O2S: C
64.43, H 4.70, N 9.39; Found: C 64.36, H 4.64, N 9.32.
3-(Thiophen-2-ylmethyl)-2-(3-(trifluoromethyl)phenylimino)
thiazolidin-4-one (4j). Yellow liquid. IR (neat): 1721, 1640,
1381, 1135. 1H NMR (300 MHz, CDCl3): d = 3.81 (d,
J = 0.8 Hz, 2H), 5.14 (s, 2H), 6.91–6.97 (m, 1H), 7.12–7.27 (m,
4H), 7.36–7.50 (m, 2H). 13C NMR (75 MHz, CDCl3): d = 32.8,
40.6, 118.1, 118.2, 121.3. 121.4, 124.4, 126.4, 126.5, 128.6,
129.8, 136.7, 148.2, 154.8, 170.8. ESI–MS [M + H+]:
3-(2,4-Difluorophenyl)-2-(3-(trifluoromethyl)phenylimino)
thiazolidin-4-one (4c).
Yellow liquid. IR (neat): 1733, 1630,
1
1364, 1180. H NMR (500 MHz, CDCl3): d =3.91–4.07 (m, 4H),
6.78–6.90 (m, 2H), 6.96–7.09 (m, 3H), 7.15 (s, 1H), 7.28–7.46 (m,
3H), 7.56–7.73 (m, 3H). 13C NMR (75 MHz, CDCl3): d = 32.7,
32.9, 104.7, 105.0, 111.1, 112.3, 117.9, 118.0, 121.3, 121.4, 122.9,
123.0, 124.2, 125.1, 125.8, 129.7, 129.8, 130.9, 131.4, 134.8,
147.9, 151.7, 154.8, 156.4, 159.6, 161.4, 164.9, 170.2, 170.8.
ESI–MS [M + H+]: m/z = 373. Anal. Calcd for C16H9F5N2OS: C
51.61, H 2.42, N 7.53; Found: C 51.54, H 2.36, N 7.48.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

U. B. Kosurkar, T. L. Dadmal, R. M. Kumbhare, and B. Sridhar
Vol 000
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[18] Yella, R.; Ghosh, H.; Patel, B. K. Green Chem 2008, 10, 1307–1312.
[19] (a) Kumbhare, R. M.; Sridhar, M. Catal Commun 2008, 9,
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[21] Crystal data: for 4a: C15H12N2OS, M = 268.33, orthorhombic,
space group Pbca, a = 10.8879(9) Å, b = 10.0574(8) Å, c = 24.2525(19)
Å, V = 2655.7(4) Å3, Z= 8, Dc = 1.342 Mgm-3, l = 0.71073 Å, m(Mo Ka )
= 0.236mm-1, F000= 1120, T= 294(2) K. Total number of measured reflec-
tions is 12413. Final refinement to convergence on F2 gave R = 0.0604 (2192
obs. data only) and Rw= 0.1304, GOF= 1.246. CCDC # 833911.
1
1137. H NMR ( 75 MHz, CDCl3): d = 3.77 (d, J = 0.8 Hz, 2H),
5.15 (s, 2H), 6.89–7.00 (m, 3H), 7.07–7.25 (m, 3H), 7.32
(t, J = 7.4 Hz, 2H). 13C NMR (75 MHz, CDCl3): d = 32.7, 40.5,
120.9, 124.7, 126.2, 126.4, 128.5, 129.2, 137.0, 147.7, 153.3,
171.0. ESI–MS [M + H+]: m/z = 289. Anal. Calcd for
C14H12N2OS2: C 58.33, H 4.17, N 9.72; Found: C 58.26, H 4.11,
N 9.66.
3-Cyclohexyl-2-(4-methoxyphenylimino)thiazolidin-4-one
(4l).
White solid. Mp 138–140ꢂC. IR (KBr): 1720, 1646,
1370, 1168. 1H NMR (500 MHz, CDCl3): d = 1.13–1.44 (m,
5H), 1.54–1.83 (m, 5H), 3.13 (s, 1H), 3.84 (s, 3H), 3.92 (d,
J = 0.9Hz, 2H), 6.94 (d, J = 8.6Hz, 2H), 7.15 (d, J = 8.6Hz,
2H). 13C NMR (75 MHz, CDCl3): d = 24.5, 25.5, 32.4, 33.2,
55.3, 61.6, 114.2, 127.9, 128.9, 149.3, 159.1, 171.6. ESI–MS
[M + H+]: m/z = 305. Anal. Calcd for C16H20N2O2S: C 63.16, H
6.57, N 9.21; Found: C 63.08, H 6.49, N 9.16.
2-(4-Chlorophenylimino)-3-cyclohexylthiazolidin-4-one
(4m). White solid; Mp 147–149ꢂC. IR (KBr): 1718, 1644,
1366, 1164. 1H NMR (75 MHz, CDCl3): d = 1.16–1.42
(m, 5H), 1.51–1.79 (m, 5H), 3.11(s, 1H), 3.92 (s, 2H), 7.16–
7.26 (m, 2H), 7.40 (d, J = 8.7 Hz, 2H). 13C NMR (75 MHz,
CDCl3): d = 24.4, 25.5, 32.5, 33.1, 61.5, 129.0, 129.2, 133.6,
134.0, 148.8, 171.1. ESI–MS [M + H+]: m/z = 309. Anal.
Calcd for C15H17ClN2OS: C 58.44, H 5.52, N 9.10; Found: C
58.36, H 5.48, N 9.04.
(Z)-3-tert-butyl-2-(phenylimino)thiazolidin-4-one (4n). White
solid. Mp 108–110ꢂC. IR (KBr): 1726, 1634, 1374, 1155. 1H
NMR (75 MHz, CDCl3): d = 1.24 (s, 9H), 3.93 (d, J= 0.8 Hz, 2H),
7.18 (d, J= 7.4 Hz, 2H), 7.29–7.47 (m, 3H). 13C NMR (75MHz,
CDCl3): d = 29.7, 33.9, 55.0, 128.4, 128.7, 129.0, 136.3, 145.2,
170.9. ESI–MS [M + H+]: m/z= 249. Anal. Calcd for C13H16N2OS:
C 62.90, H 6.46, N 11.29; Found: C 62.82, H 6.38, N 11.21.
3-Cyclopropyl-2-(3-(trifluoromethyl)phenylimino)thiazolidin-
4-one (4o).
Yellow liquid. IR (neat): 1730, 1637, 1372, 1171,
697. 1H NMR (75MHz, CDCl3): d =0.70–1.15 (m, 4H), 2.71–2.83
(m, 1H), 3.74 (d, J=0.8Hz, 2H), 7.07 (d, J=7.6Hz, 1H), 7.33–
7.49 (m, 2H). 13C NMR (300 MHz, CDCl3): d = 6.6, 25.8, 32.4,
118.1, 121.1, 124.2, 125.2, 129.6, 131.3, 148.9, 156.5, 171.8. ESI–
MS [M + H+]: m/z= 301. Anal. Calcd for C13H11F3N2OS: C 52.0,
H 3.67, N 9.33; Found: C 51.94, H 3.61, N 9.26.
Acknowledgments. We are thankful to Dr. J. S. Yadav,
Director of IICT, for providing facilities, U.K. thanks CSIR,
T. D. thanks UGC, New Delhi, for the award of a fellowship,
and R. M. K. thanks SERC, Department of Science and
Technology, Government of India for financial assistance
under the Fast Track Scheme for young scientists (SR/FTP/
CS-93/2006).
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet