Potassium carbonate catalyzed one pot four-component synthesis of rhodanine derivatives

Article abstract of DOI:10.1016/j.tetlet.2013.03.004

A novel multicomponent synthesis of ketene dithioacetal rhodanines has been reported by reactions of primary amine, carbon disulfide, ethyl chloroacetate, and alkyl halide in DMF. The catalytic effects of different bases have been investigated and potassium carbonate can efficiently catalyze the reaction in moderate to good yields at room temperature.

Full text of DOI:10.1016/j.tetlet.2013.03.004

Accepted Manuscript
Potassium carbonate catalyzed one pot four-component synthesis of rhodanine
derivatives
Sarangthem Joychandra Singh, S.M.S. Chauhan
PII:
S0040-4039(13)00369-9
DOI:
http://dx.doi.org/10.1016/j.tetlet.2013.03.004
TETL 42617
Reference:
To appear in:
Tetrahedron Letters
Received Date:
Revised Date:
Accepted Date:
22 December 2012
27 February 2013
2 March 2013
Please cite this article as: Singh, S.J., Chauhan, S.M.S., Potassium carbonate catalyzed one pot four-component
synthesis of rhodanine derivatives, Tetrahedron Letters (2013), doi: http://dx.doi.org/10.1016/j.tetlet.2013.03.004
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Graphical Abstract
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Potassium carbonate catalyzed one pot four-component
synthesis of rhodanine derivatives
Sarangthem Joychandra Singh and S. M. S. Chauhan∗
SCH3
S
H3CS
Cl
CH3I
4
Br
Br
S
S
O
4
R
NH2
+
CS2
2
+
S
S
O
N
R
O
3
K2CO3/DMF
8 h, r..t
S
K2CO3/DMF
8 h, r..t
O
N
R
1
5
5

1
Tetrahedron Letters
journal homepage: www.elsevier.com
Potassium carbonate catalyzed one pot four-component synthesis of rhodanine derivatives
Sarangthem Joychandra Singh and S. M. S. Chauhan∗
Bio-organic laboratory, Department of Chemistry, University of Delhi, Delhi-110007, India
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A novel multicomponent synthesis of ketene dithioacetal rhodanines has been reported by
reactions of primary amine, carbon disulfide, ethyl chloroacetate, and alkyl halide in DMF. The
catalytic effects of different bases have been investigated and potassium carbonate can
efficiently catalyze the reaction in moderate to good yields at room temperature.
Available online
Keywords:
Rhodanine
Potassium carbonate
Multicomponent reactions
Ketene dithioacetal
Amines
2009 Elsevier Ltd. All rights reserved.
11
12
Multicomponent reactions (MCRs) are one of the most
important methods for the synthesis of natural products,
medicinal, and combinatorial chemistry in recent years.1 These
reactions avoid time consuming and costly processes for
purification of various precursors and isolation of intermediates.2
Multicomponent reactions are often accompanied by significant
increases in molecular complexity and impressive selectivity.3
Therefore, the development of new methodology for
multicomponent reactions is very important in the fields of
organic and medicinal chemistry.
rhodanine
and 2-amino 4-thiazolones
have been reported.
Besides these, highly functionalized two-component rhodanine
derivatives13 and four-component rhodanine derivatives have
been achieved.14
A careful literature survey reveals that there have been no
reports on the synthesis of ketene dithioacetal rhodanines via one
pot four-component reactions. However, there are a few reports
on the synthesis of heterocyclic ketene dithioacetals.15 In
continuation of our efforts to develop biologically active
heterocycles,16 we report herein potassium carbonate catalyzed
synthesis of novel ketene dithioacetal rhodanines via one pot,
four-component reactions of primary amines, carbon disulfide,
ethylchloroacetate and alkyl halides in DMF (Scheme 1).
Rhodanine-based molecules are known to possess diverse
4a
biological activities through the inhibition of numerous targets
such as HIV-1,4b Alzheimer’s deseases,4c HCV NS3 protease,4d β-
lactamase,4e PMT1 mannosyl transferase,4f PRL-3 and JSP-1
phosphatases.4g Additionally, they have been reported to possess
SCH3
5d
antimicrobial,5a antiviral,5b anticonvulsant,5c antidiabetic
and
CH3I
(2 eq.)
4
Br
Br
(1eq.)
S
H3CS
Cl
S
antitumor activities.5e The unusual biological activity displayed
by many rhodanine-based molecules have made them attractive
synthetic targets.
S
O
S
4
R
NH2
+
CS2
+
S
O
N
R
K2CO3/DMF
8 h, r..t
O
(1eq.)
3
S
O
(2 eq.)
N
R
(1eq.)
1
K2CO3/DMF
8 h, r..t
2
5
5
Rhodanine derivatives have been synthesized so far by
assembling the functionalized heterocycles through the reaction
of α-halogencarboxylic acid and maleic acid derivatives with
carbon disulfide and amines or that of isothiocyanates with
thioglicolates.6 Recently, three-component, one-flask preparation
of 5-arylidene rhodanines,7 5-hydrazinoalkylidene rhodanines,8
5-acyl rhodanines,9 5-carboxymethyl rhodanines,10 5-alkylidene
Scheme 1. Synthesis of ketene dithioacetal rhodanines.
In a preliminary experiment, the synthesis of 3-cyclopropyl-5-
(1,3-dithiolan-2-ylidene)-2-thioxothiazolidin-4-one 5a was
carried out by four-component reaction of cyclopropyl amine (1
mmol), carbon disulfide (2 mmol), ethylchloroacetate (1 mmol),
and 1,2-dibromoethane (1 mmol) in DMF using K2CO3 as a
catalyst (Table 1). The progress of the reaction was monitored by
———
∗ Corresponding author. Tel.: 91-11-27666845; fax: 91-11-27666845; e-mail: smschauhan@chemistry.du.ac.in

2
Tetrahedron
thin layer chromatography (TLC). The reaction went smoothly
resistant to nucleophilic attack by the carbonium ion. Thus,
benzylamine having methoxy group gave higher yield than
chloro substituent at the ortho position. As can be seen from
Table 2, the product of cyclic amines is more than acyclic
amines. However, the reaction failed when aromatic amine was
utilized in the same reaction, this phenomenon probably resulted
from the decrease of nucleophilicity of the nitrogen atom. The
and the product 5a was obtained in good yield. Encouraged by
this result, other bases such as K3PO4, sodium ethoxide and
triethylamine were screened. However, the use of K3PO4 and
sodium ethoxide afforded poor yields of the product whereas
triethylamine gave moderate yield. To further improve the
efficiency of this synthetic approach, the template reaction was
also carried out in the presence of different organic solvents such
as acetonitrile, benzene and THF, all of which lowered the
reaction yield.
structure of all the products were characterized by IR, 1NMR, 13
C
NMR, CHN analysis, and mass spectrometry,17 and the structure
of 5i was additionally confirmed by the single-crystal X-ray
diffraction (Figure 1).18
Table 1. Synthesis of 3-cyclopropyl-5-(1,3-dithiolan-2-ylidene)-
2-thioxothiazolidin-4-one a
Table 2. Synthesis of ketene dithioacetal rhodanines a
S
S
Cl
SR1
S
Cl
O
K2CO3/DMF
r..t
NH2
1a
+
CS2
2a
+
+
Br
Br
4a
R1S
S
O
O
R1
-X
O
+
CS2
2
+
R-NH2
1a-h
N
DMF/K2CO3
S
+
O
3
S
3a
O
r.t, 8h
N
R
4
5a
4a, R1X = C2H4Br2
4b, R1X = CH3I
5a-m
c Yield (%)
Catalyst bCatalyst (mol %) Solvent
Entry
Time (h)
1
2
3
K2CO3
K2CO3
K2CO3
DMF
DMF
DMF
8
8
8
70
58
37
50
40
30
4
5
6
K2CO3
K2CO3
K2CO3
20
50
DMF
8
8
8
15
30
20
Benzene
Acetonitrile
50
50
7
8
K2CO3
Et3N
THF
9
50
55
35
20
50
DMF
10
8
K2PO4
NaOEt
none
DMF
DMF
DMF
50
50
-
9
15
24
10
11
nil
a
Reaction conditions: Cyclopropylamine (1 mmol), carbondisulfide (2
mmol), ethylchloroacetate (1 mmol) and 1,2-dibromoethane (1 mmol) at r.t.
b Amount of catalyst used base on 1a.
c Isolated yield after silica gel chromatography.
To optimize the catalyst loading, above model reaction was
carried out in the presence of 20 mol %, 30 mol %, 40 mol % and
50 mol % K2CO3 (Table 1, entries 1-4). It was observed that 50
mol % K2CO3 gave maximum yield (Table 1, Entry 1). Thus, the
use of 50 mol % K2CO3 was considered to be the most effective
catalyst for the reaction. Higher the percentage loading of the
catalyst neither increased the yield nor reduced the reaction time.
It is important to note that when the amount of catalyst is
reduced, a decrease in the yield was observed. This is presumably
because part of the catalyst is consumed for neutralization of
forming hydrogen halide during the reaction. In contrast to the
above results, the reaction without catalyst did not afford the
desired product.
Under the above optimized conditions, the scope of this new
MCR process was examined using various readily available
starting materials. As revealed in Table 2, a range of invaluable
ketene dithioacetal rhodanine derivatives (5a-m) can be
synthesized in moderate to good yields. The yields of cyclic
ketene dithioacetals were found to be higher than acyclic ketene
dithioacetals. Among the different aliphatic primary amines,
cyclopropylamine and ethyl amine gave higher yields (Table 1,
entry 1, 3, 9). This is due to the fact that +I effect of alkyl groups
raises the energy of the lone pair of electrons, thus elevating the
basicity. Without enough electron cloud, the N atom was more

3
a Reaction conditions: Amine (1 mmol), carbondisulfide (2 mmol),
ethylchloroacetate (1 mmol) and 1,2-dibromoethane (1 mmol), K2CO3 (50
mol %), r.t., 8 h.
R
1-X
bYield (%)
R-NH2
Entry
Product
m.p (oC)
S
1
S
NH2
4a
156-157
70
S
bIsolated yield after silica gel chromatography
1a
S
O
N
5a
S
S
2
CH3-NH2
1b
4a
S
169-170
125-126
61
65
S
O
N
5b
S
S
3
CH3-CH2-NH2
1c
4a
S
S
O
N
5c
S
S
NH2
S
4
4a
S
O
N
150-151
56
59
1d
5d
S
S
NH2
4a
S
5
S
H3CO
147-148
O
N
Figure 1. X-ray crystal structure (ORTEP plot) of 5i
1e
5e
OCH3
On the basis of the experimental results, a plausible
mechanism for the formation of ketene dithioacetal rhodanine is
presented in Scheme 2. The initial step in this reaction is the
nucleophilic attack of amine 1 to carbon disulfide to afford the
key intermediate A, which subsequently reacts with 3 to form
another intermediate B, which undergoes an intramolecular ring
cyclization to give the rhodanine C. The deprotonation of
rhodanine C afforded enolate D which reacts with CS2 to form
thiolate E. The monothiolate anion F undergoes mono-alkylation
with alkyl halide to afford dithio alkyl ester G. Then it undergoes
enolization and another alkylation to give the corresponding
ketene dithioacetal rhodanine 5.
S
S
6
NH2
S
4a
Cl
1f
S
154-155
O
N
53
5f
Cl
S
7
NH2
4a
S
S
120-121
162-163
1g
47
43
S
5g
O
N
S
S
8
S
NH2
4a
S
O
N
N
H
O
O
1h
5h
5i
K
Cl-CH2-C OEt
3
S
EtO
S
HN
K2CO3
R
CS2
2
R-NH2
1
+
N
S
R
N
S
H
SCH3
H
H3CS
9
S
B
NH2
4b
A
101-102
68
S
O
N
1a
S
S
S
S
K2CO3
S
S
CS2
S
O
O
K
N
N
SCH3
S
R1
O
R1
N
H3CS
S
10
CH3-NH2
1b
R1
4b
4b
C
119-120
106-107
55
49
D
S
O
N
E
5j
SCH3
SR1
SH
H3CS
NH2
S K
N
S
11
R1S
S
K
R1S
S
O
N
S
R1X
R1X
K2CO3
S
S
1d
5k
S
S
O
S
O
N
R1
N
R1
K2CO3
O
R1
SCH3
F
5
G
H3CS
S
NH2
45
12
4b
92-93
S
O
N
Scheme 2. K2CO3 catalyzed synthesis of ketene dithioacetal
1g
5l
rhodanines
SCH3
H3CS
In conclusion, we have successfully described
a novel
S
S
O
N
NH2
multicomponent reactions for the efficient synthesis of
structurally diverse ketene dithioacetal rhodanine derivatives.
The reaction approach using cheap and readily available starting
materials make this new strategy highly attractive in diversity
oriented synthesis. Furthermore, this series of ketene dithioacetal
rhodanine derivatives may provide new class of biologically
active compounds for biomedical screening, which is in
progress in our laboratory.
4b
144-145
40
13
N
H
1h
HN
5m
Acknowledgment
This work was sponsored by the UGC under the Dr. D.S.
Kothari post-doctoral fellowship scheme. We also thank the
Department of Science and Technology and University of Delhi,
Delhi for financial assistance.

4
Tetrahedron
References and notes
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17. General Procedures for the synthesis of ketene dithioacetal
rhodanines (5a-m): K2CO3 (50 mol %) was added to a mixture of
amine (1 mmol), CS2 (2 mmol) and ethyl chloroacetate (1 mmol)
in 5 ml of DMF at room temperature and the mixture was stirred
for
3 h. Subsequently, methyl iodide (2 mmol) or 1,2-
dibromoethane (1 mmol) was added dropwise and stirred for
another 5 h at room temperature. After completion of the reaction,
the mixture was extracted with EtOAc (1 × 10 mL), and the
combined organic layers were dried with anhyd. Na2SO4. The
residue was subjected to silica gel chromatography Hex–EtOAc
(5:1) as eluents to give pure products.
3-cyclopropyl-5-(1,3-dithiolan-2-ylidene)-2-thioxothiazolidin-
4-one (5a): yellow solid; IR (KBr) (ν max, cm−1): 1670, 1508,
1240; 1H NMR (CDCl3, 400 MHz, δ ppm): 1.03-1.04 (m, 2H),
1.11-1.14 (m, 2H), 2.79-2.85 (m, 1H), 3.50-3.53 (m, 2H), 3.58-
3.61 (m, 2H); 13C NMR (CDCl3, 75 MHz, δ ppm): 7.2, 27.9, 37.7,
39.4, 107.8, 154.1, 164.9, 192.3; EI MS (m/z): 275 (M+). Anal.
Calcd for C9H9NOS4: C, 39.25; H, 3.29; N, 5.09; S, 46.57%.
Found: C, 39.29; H, 3.21; N, 5.13; S, 46.56%.
5-(1,3-dithiolan-2-ylidene)-3-methyl-2-thioxothiazolidin-4-one
(5b): yellow solid; IR (KBr) (ν max, cm−1): 1669, 1522, 1282; 1H
NMR (CDCl3, 400 MHz, δ ppm): 3.45 (s, 3H), 3.53-3.56 (m, 2H),
3.61-3.64 (m, 2H); 13C NMR (CDCl3, 75 MHz, δ ppm): 31.4, 37.9,
39.5, 108.4, 145.4, 164.3, 190.9; EI MS (m/z): 249 (M+). Anal.
Calcd for C7H7NOS4: C, 33.71; H, 2.83; N, 5.62; S, 51.4%. Found:
C, 33.79; H, 2.77; N, 5.65; S, 51.7%.
5-(1,3-dithiolan-2-ylidene)-3-ethyl-2-thioxothiazolidin-4-one
(5c): yellow solid; IR (KBr) (ν max, cm−1): 1663, 1522, 1270; 1H
NMR (CDCl3, 400 MHz, δ ppm): 1.19-1.26 (m, 3H), 3.49-3.54
(m, 2H), 3.58-3.63 (m, 2H), 4.08-4.14 (m, 2H); 13C NMR (CDCl3,
75 MHz, δ ppm): 12.1, 37.8, 39.5, 39.9, 107.7, 154.6, 164.1,
190.6; EI MS (m/z): 263 (M+). Anal. Calcd for C8H9NOS4: C,
36.48; H, 3.44; N, 5.32. 48.69%. Found: C, 36.51; H, 3.39; N,
5.35; S, 48.72%.
3-benzyl-5-(1,3-dithiolan-2-ylidene)-2-thioxothiazolidin-4-one
(5d): yellow solid; IR (KBr) (ν max, cm−1): 1676, 1508, 1185; 1H
NMR (CDCl3, 400 MHz, δ ppm): 3.50-3.53 (m, 2H), 3.59-3.62
(m, 2H), 5.24 (s, 2H), 7.24-7.34 (m, 3H), 7.44 (d, J = 7.3 Hz, 2H);
13C NMR (CDCl3, 75 MHz, δ ppm): 37.9, 39.5, 47.7, 107.4, 127.9,
128.4, 128.9, 135.0, 155.3, 164.2, 190.6. EI MS (m/z): 325 (M+).
Anal. Calcd for C13H11NOS4: C, 47.97; H, 3.41; N, 4.30, S,
39.40%. Found: C, 47.89; H, 3.49; N, 4.33; S, 39.45%.
6. Ugi, I. Angew. Chem., Int. Ed. 1982, 21, 810–819.
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3-(4-methoxybenzyl-5-(1,3-dithiolan-2-ylidene)-2-
14. (a) Bernardo, P. H.; Sivaraman, T.; Wan, K. F.; Xu, J.;
Krishnamoorthy, J.; Song, C. M.; Tian, L.; Chin, J. S. F.; Lim, D.
S. W.; Mok, H. Y. K.; Yu, V. C.; Tong, J. C.; Chai, C. L. L. J.
Med. Chem. 2010, 53, 2314-2318 ; (b) Chai, C. L. L.; Bernardo, P.
H.; Xu, J.; Yu, V. C.; Wan, K. F.; Mok, H. Y. K.; Sivaraman, T.;
Krishnamoorthy, J.; PCT Int. Appl. 2010024783.
15. (a) Tominaga, Y.; Sone, M.; Mizuyama, K.; Matsuda, Y.;
Kobayashi, G. Chem. Pharm. Bull. 1976, 24, 1671-1675; (b)
Tominaga, Y.; Morita, Y.; Matsuda, Y.; Kobayashi, G. Chem.
Pharm. Bull. 1975, 23, 2390-2396; (c) Kobayashi, G.; Matsuda,
Y.; Tominaga, Y.; Ohkuma, M.; Shinoda, H. Yakugaku
Zasshi.1977, 9, 1039-1045; (d) Yokota, K.; Hagimori, M.;
Mizuyama, N.; Nishimura, Y.; Fujito, Hiroshi.; Shigemitsu, Y.;
Tominaga, Y. Beilstein J. Org. Chem. 2012, 8, 266-274.
thioxothiazolidin-4-one (5e): yellow solid; IR (KBr) (ν max,
cm−1): 1671, 1506, 1179; 1H NMR (CDCl3, 400 MHz, δ ppm):
3.50-3.53 (m, 2H), 3.59-3.62 (m, 2H), 3.76 (s, 3H), 5.19 (s, 2H),
6.79 (d, J = 8.8 Hz, 2H), 7.43 (d, J = 8.7 Hz, 2H); 13C NMR
(CDCl3, 75 MHz, δ ppm): 37.8, 39.5, 47.2, 55.2, 113.7, 114.2,
127.3, 128.3, 130.6, 155.0, 164.1, 190.1; EI MS (m/z): 355 (M+).
Anal. Calcd for C14H13NO2S4: C, 47.30; H, 3.69; N, 3.94; S,
36.08%. Found: C, 47.35; H, 3.67; N, 3.97; S, 36.04%.
3-(2-chlorobenzyl-5-(1,3-dithiolan-2-ylidene)-2-
thioxothiazolidin-4-one (5f): yellow solid; IR (KBr) (ν max,
cm−1): 1678, 1508, 1187; 1H NMR (CDCl3, 400 MHz, δ ppm):
3.50-3.53 (m, 2H), 3.59-3.62 (m, 2H), 5.27 (s, 2H), 7.28-7.36 (m,
4H); 13C NMR (CDCl3, 75 MHz, δ ppm): 37.9, 39.5, 47.8, 113.9,
126.5, 126.9, 128.7, 129.8, 131.4, 135.1, 155.0, 164.3, 190.8; EI
MS (m/z): 359 (M+). Anal. Calcd for C13H10ClNOS4: C, 43.38; H,
2.80; N, 3.89; S, 35.63%. Found: C, 43.35; H, 2.82; N, 3.87; S,
35.60%.
16. (a) Singh, S. J.; Ahmad, S.; Chauhan, S. M. S. J. Heterocyclic
Chem. 2012 (accepted manuscript ID JHET-12-0253.R2); any

5
3-allyl-5-(1,3-dithiolan-2-ylidene)-2-thioxothiazolidin-4-one
(5g): yellow solid; IR (KBr) (ν max, cm−1): 1671, 1520, 1214; 1H
NMR (CDCl3, 400 MHz, δ ppm): 3.52-3.55 (m, 2H), 3.60-3.63
(m, 2H), 4.6 ( d, J = 5.8 Hz, 2H), 5.18-5.28 (m, 2H), 5.77-5.86 (m,
1H)); 13C NMR (CDCl3, 75 MHz, δ ppm): 29.8, 37.9, 39.5, 46.4,
107.6, 119.4, 154.3, 163.7, 190.5; EI MS (m/z): 275 (M+).
Anal.Calcd for C9H9NOS4: C, 39.25; H, 3.29; N, 5.09; S, 46.57%.
Found: C, 39.27; H, 3.26; N, 5.05; S, 46.53%.
3-(2-(1H-indol-3-yl)ethyl-5-(1,3-dithiolan-2-ylidene)-2-
thioxothiazolidin-4-one (5h): yellow solid; IR (KBr) (ν max,
cm−1): 1654, 1517, 1178; 1H NMR (CDCl3, 400 MHz, δ ppm):
3.10-3.14 (t, 2H), 3.52-3.55 (m, 2H), 3.59-3.64 ( m, 2H), 4.31-
4.35 (t, 2H), 7.04-7.20 (m, 3H), 7.33 (d, J = 8.01 Hz, 1H), 7.83
(d, J = 8.03 Hz, 1H), 8.01 (s, 1H); 13C NMR (CDCl3, 75 MHz, δ
ppm): 22.8, 37.8, 39.5, 45.6, 111.1, 111.3, 119.1, 119.5, 122.1,
122.2, 122.9, 127.3, 136.1, 154.7, 164.1, 190.6; EI MS (m/z): 378
(M+). Anal.Calcd for C16H14N2OS4: C, 50.76; H, 3.73; N, 7.40; S,
33.88%. Found: C, 50.78; H, 3.70; N, 7.43; S, 33.86%.
5-(bis(methylthio)methylene)-3-cyclopropyl-2-
thioxothiazolidin-4-one (5i): Yellow solid; IR (KBr) ( ν max, cm-
1
1): 1685, 1508, 1249; H NMR (CDCl3, 400 MHz, δ ppm): 1.01-
1.04 (m, 2H), 1.12-1.14 (m, 2H), 2.47 (s, 3H), 2.59 (s, 3H), 2.78-
2.82 (m, 1H); 13C NMR (CDCl3, 75 MHz, δ ppm): 7.3, 17.7, 18.9,
27.7, 124.5, 149.0, 163.5, 194.3; EI MS (m/z): 277 (M+).
Anal.Calcd for C9H11NOS4: C, 38.96; H, 4.00; N, 5.05; S, 46.23%.
Found: C, 38.83; H, 4.13; N, 5.13; S, 46.33%.
5-(bis(methylthio)methylene)-3-methyl-2-thioxothiazolidin-4-
one (5j). yellow solid; IR (KBr) (ν max, cm−1): 1685, 1500, 1289;
1H NMR (CDCl3, 400 MHz, δ ppm): 2.48 (s, 3H), 2.60 (s, 3H),
3.41 (s, 3H); 13C NMR (CDCl3, 75 MHz, δ ppm): 17.8, 18.9, 31.0,
124.5, 149.9, 162.5, 192.7; EI MS (m/z): 251 (M+). Anal.Calcd for
C7H9NOS4: C, 33.44; H, 3.61; N, 5.57; S, 51.02%. Found: C,
33.37; H, 3.59; N, 5.29; S, 51.09%.
3-benzyl-5-(bis(methylthio)methylene)-2-thioxothiazolidin-4-
one (5k). yellow solid; IR (KBr) (ν max, cm−1): 1683, 1507,
1
1193; H NMR (CDCl3, 400 MHz, δ ppm): 2.47 (s, 3H), 2.59 (s,
3H), 5.23 (s, 2H), 7.25-7.28 (m, 3H), 7.45-7.47 (m, 2H); 13C NMR
(CDCl3, 75 MHz, δ ppm): 16.6, 17.7, 28.4, 46.2, 123.3, 126.7,
127.2, 127.9, 133.7, 161.5, 191.3; EI MS (m/z): 327(M+).
Anal.Calcd for C13H13NOS4: C, 47.67; H, 4.00; N, 4.28; S,
39.16%. Found: C, 47.55; H, 4.11; N, 4.39; S, 39.28%.
3-allyl-5-(bis(methylthio)methylene)-2-thioxothiazolidin-4-one
1
(5l). yellow solid; IR (KBr) (ν max, cm−1): 1687, 1520, 1217; H
NMR (CDCl3, 400 MHz, δ ppm): 2.50 (s, 3H), 2.61 (s, 3H), 4.64
(d, J = 7.32 Hz, 2H), 5.19-5.29 (m, 2H), 5.77-5.87 (m, 1H); 13C
NMR (CDCl3, 75 MHz, δ ppm): 17.9, 18.9, 29.6, 46.4, 119.4,
129.5, 150.0, 162.3, 192.3; EI MS (m/z): 277 (M+). Anal.Calcd for
C9H11NOS4: C, 38.96; H, 4.00; N, 5.05; S, 46.23%. Found: C,
38.73; H, 4.17; N, 5.21; S, 46.27%.
3-(2-(1H-indol-3-yl)ethyl)-5-(bis(methylthio)methylene)-2-
thioxothiazolidin-4-one (5m). yellow solid; IR (KBr) (ν max,
cm−1): 1663, 1499, 1176; 1H NMR (CDCl3, 400 MHz, δ ppm):
2.50 (s, 3H), 2.57 (s, 3H), 3.10-3.14 (t, 2H), 4.30-4.34 (t, 2H),
7.08-7.19 (m, 3H), 7.32 (d, J = 8.04, 1H), 7.80 (d, J = 8.08 Hz,
1H), 8.02 (s, 1H); 13C NMR (CDCl3, 75 MHz, δ ppm): 17.9, 18.9,
22.8, 45.1, 111.0, 112.0, 119.1, 119.5, 122.1, 122.3, 124.7, 127.5,
136.1, 149.2, 162.5, 192.7; EI MS (m/z): 380 (M+). Anal. Calcd
for C16H16N2OS4: C, 50.50; H, 4.24; N, 7.36; S, 33.70%. Found: C,
50.37; H, 4.39; N, 7.26; S, 33.77%.
18. Crystallographic data for the X-ray crystal structure analysis
reported in this paper have been deposited with Cambridge
Crystallographic Data Center (CCDC) as supplementary
publication no. CCDC-924030. Copies of the data can be obtained
free of charge on application to the Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: + 44-1223-336-033, e-mail:
deposit@ccdc.cam.ac.uk).