Synthesis of oxoindolin-3-ylidene-1,3-dithioles

Article abstract of DOI:10.1007/s13738-011-0028-5

An efficient and one-pot synthesis of 2-(2-oxoindolin-3-ylidene)-1,3- dithiole-4,5-dicarboxylates by a three-component condensation reaction of isatins, carbon disulfide and dialkyl acetylendicarboxylates in the presence of Bu3P is reported. Reaction of carbon disulfide and dialkyl acetylene dicarboxylates with acenaphthylene-1,2-dione, ninhydrine and pyrimidine-tetraone resulted in the formation of 2-(2-oxoacenaphthylen-1(2H)-ylidene)-1,3-dithiole- 4,5-dicarboxylates, 2-(1,3-dioxo-1H-inden-2 (3H)-ylidene)-1,3-dithiole-4,5- dicarboxylates and 2-(2,4, 6-trioxotetrahydropyrimidin-5(6H)-ylidene)-1,3- dithiole-4, 5-dicarboxylates, respectively, in the same conditions.

Full text of DOI:10.1007/s13738-011-0028-5

J IRAN CHEM SOC (2012) 9:333–338
DOI 10.1007/s13738-011-0028-5
ORIGINAL PAPER
Synthesis of oxoindolin-3-ylidene-1,3-dithioles
•
S. Ahadi Gh. Hosseini A. Bazgir
•
Received: 17 January 2011 / Accepted: 19 August 2011 / Published online: 3 January 2012
Ó Iranian Chemical Society 2011
Abstract An efficient and one-pot synthesis of
2-(2-oxoindolin-3-ylidene)-1,3-dithiole-4,5-dicarboxylates
by a three-component condensation reaction of isatins,
carbon disulfide and dialkyl acetylendicarboxylates in the
presence of Bu3P is reported. Reaction of carbon disulfide
and dialkyl acetylene dicarboxylates with acenaphthylene-
1,2-dione, ninhydrine and pyrimidine-tetraone resulted
in the formation of 2-(2-oxoacenaphthylen-1(2H)-ylidene)-
1,3-dithiole-4,5-dicarboxylates, 2-(1,3-dioxo-1H-inden-2
(3H)-ylidene)-1,3-dithiole-4,5-dicarboxylates and 2-(2,4,
6-trioxotetrahydropyrimidin-5(6H)-ylidene)-1,3-dithiole-4,
5-dicarboxylates, respectively, in the same conditions.
simpler operational procedure, milder reaction condition,
higher yield of products coupled with potential bioactivity
is in demand.
Derivatives of sulfur heterocycles such as thiophene and
1,3-dithiole have been widely explored as new materials
because of their superconducting optical and electronic
switching properties [11]. 1,3-Dithiol-2-ylidenes have
attracted much attention as building blocks for electronic
materials due to their highly electron-donating properties
[12, 13]. Therefore, due to the importance of 1,3-dithioles,
various methods have been reported for the synthesis of
1,3-dithiole derivatives [12–22].
Despite of continuous research for the synthesis of
heterocyclic indoline ring system and polysulfur hetero-
cycle derivatives, only a limited number of indoles fused
polysulfur heterocycles have been reported [23]. Therefore,
as part of our program aimed at developing new method-
ologies for the preparation of heterocycles [24–31], we
report here an efficient synthesis of 2-(2-oxoindolin-3-yli-
dene)-1,3-dithiole-4,5-dicarboxylates 4 via a three-com-
ponent reaction of dialkyl acetylenedicarboxylate 1, carbon
disulfide 2 and isatins 3 in the presence of tributylphos-
phine based on Wittig reaction (Scheme 1).
Keywords Isatin Á Oxindole Á Oxoindolin-3-ylidene-1 Á
3-dithiole Á 1,3-Dithiole
Introduction
The heterocyclic indole and indoline ring system is a
widely distributed structural framework present in a num-
ber of pharmaceuticals and natural products [1], and some
of indolines, oxindole derivatives, have shown high bio-
logical activities. Oxindoles are known to possess anti-
bacterial, antiprotozoal, and anti-inflammatory activities
and are also patented as progesterone receptors agonists
[2–5]. The varied biological activities of oxindole deriva-
tives have attracted the synthetic chemists to a number of
synthetic strategies [6–10]. Therefore, the development of
methodologies using novel reagents with greater efficiency,
Experimental
Melting points were measured on an Electrothermal 9100
1
apparatus and are uncorrected. H and 13C NMR spectra
were measured on a BRUKER DRX-300 AVANCE spec-
1
trometer at 300.13 and 75.47 MHz, respectively. H and
13C NMR spectra were obtained on solutions in DMSO-d6.
IR spectra were recorded using an FTIR apparatus. Ele-
mental analyses were performed using a Heracus CHN-O-
Rapid analyzer. The chemicals used in this work were
S. Ahadi Á Gh. Hosseini Á A. Bazgir (&)
Department of Chemistry, Shahid Beheshti University,
G.C., 1983963113 Tehran, Iran
e-mail: a_bazgir@sbu.ac.ir
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J IRAN CHEM SOC (2012) 9:333–338
Scheme 1 Synthesis of
oxoindolin-3-ylidene-
1,3-dithioles 4
CO2R
CO2R
S
O
O
OR
X
O
S
CH2Cl2, r.t.
X
O
+
CS2
+
O
NR1
P(Bu)3
3-18 h
NR1
4a-p
OR
1a-c
2
3a-h
136.0, 139.5, 146.5, 159.3, 160.1, 164.4. Anal. Calcd for
C17H15NO5S2: C, 54.10; H, 4.01; N, 3.71. Found: C, 54.19;
H, 4.92; N, 3.61.
purchased from Fluka and Merck and were used without
purification.
General procedure for the preparation
of oxoindolin-3-ylidene-1,3-dithioles
Dimethyl 2-(1-benzyl-2-oxo-1,2-dihydro-3H-indol-3-yli-
dene)-1,3-dithiole-4,5-dicarboxylate (4d) Yellow powder
(yield 91%); mp 178–179 °C. IR (KBr) (mmax/cm-1): 17.16,
1,654. 1H NMR (300 MHz, DMSO-d6): dH (ppm) 3.81(3H,
s, CH3), 3.89(3H, s, CH3), 4.99 (2H, s, CH2), 7.01–7.29 (9H,
m, H–Ar). 13C NMR (75 MHz, DMSO-d6): dC (ppm) 43.2,
54.4, 109.6, 109.8, 121.0, 121.4, 122.5, 127.3, 127.7, 127.8,
129.1, 129.5, 136.0, 137.1, 139.5, 147.6, 159.3, 160.1, 164.9.
Anal. Calcd for C22H17NO5S2: C, 60.12; H, 3.90; N, 3.19.
Found: C, 60.03; H, 3.83; N, 3.12.
To a magnetically stirred solution of carbon disulfide
(1 mmol) and tributylphosphine (1 mmol) in CH2Cl2
(5 mL) for 0.5 h were added isatin (1 mmol) and dimethyl
acetyenedicarboxylate (1 mmol) at room temperature. The
mixture was finally stirred for 2.5 h. After completion of
the reaction (TLC), the reaction mixture was filtered off
and the residue was washed with ether (10 mL) to afford
the pure product 4.
Dimethyl 2-(5-bromo-2-oxo-1,2-dihydro-3H-indol-3-yli-
dene)-1,3-dithiole-4,5-dicarboxylate (4e) Yellow powder
(yield 83%); mp 285–287 °C. IR (KBr) (mmax/cm-1):
Dimethyl 2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-1,3-
dithiole-4,5-dicarboxylate (4a) Orange powder (0.35 g,
yield 98%). MP 229–231 °C. IR (KBr) (mmax/cm-1): 3,017,
1
3,446, 3,127, 1,756, 1,666. H NMR (300 MHz, DMSO-
1
1,741, 1,713. H NMR (300 MHz, DMSO-d6): dH (ppm)
d6): dH (ppm) 3.80 and 3.87 (6H, s, 2CH3), 6.84–7.73 (3H,
m, H–Ar), 10.98 (1H, s, NH). Anal. Calcd for
C15H10BrNO5S2: C, 42.07; H, 2.35; N, 3.27. Found: C,
42.18; H, 2.29; N, 3.16.
3.96 (6H, s, 2CH3), 6.99–7.40 (4H, m, H–Ar), 8.15 (1H, s,
NH). Anal. Calcd for C15H11NO5S2: C, 51.57; H, 3.17; N,
4.01. Found: C, 51.46; H, 3.11; N, 3.94. (Due to the very
low solubility of product 4a, we were unable to obtain the
13C NMR spectrum).
Due to very low solubility of the products 4e–i, we
cannot report the 13C NMR data for these products.
Dimethyl 2-(1-methyl-2-oxo-1,2-dihydro-3H-indol-3-yli-
dene)-1,3-dithiole-4,5-dicarboxylate (4b) Orange powder
(yield 94%); mp 237–239 °C, lit.16 mp 242–244 °C. IR
(KBr) (mmax/cm-1): 1,715, 1,672. 1H NMR (300 MHz,
DMSO-d6): dH (ppm) 3.33 (3H, s, CH3), 3.87 (6H, s,
2CH3), 7.06–7.30 (4H, m, H–Ar). 13C NMR (75 MHz,
DMSO-d6): dC (ppm) 26.4, 54.3, 109.0, 110.2, 120.8,
121.2, 122.3, 127.4, 129.3, 135.9, 140.6, 146.6, 159.3,
160.1, 164.8. Anal. Calcd for C16H13NO5S2: C, 52.88; H,
3.61; N, 3.85. Found: C, 52.74; H, 3.69; N, 3.77.
Dimethyl 2-(5-nitro-2-oxo-1,2-dihydro-3H-indol-3-ylidene)-
1,3-dithiole-4,5-dicarboxylate (4f) Yellow powder (yield
86%); mp 280–282 °C. IR (KBr) (mmax/cm-1): 3,184,
1
1,716, 1,685. H NMR (300 MHz, DMSO-d6): dH (ppm)
3.88 and 3.89 (6H, s, 2CH3), 6.77–8.08 (3H, m, H–Ar),
11.45 (1H, s, NH). Anal. Calcd for C15H10N2O7S2: C,
45.68; H, 2.56; N, 7.10. Found: C, 45.79; H, 2.63; N, 7.01.
Dimethyl 2-(5-bromo-1-ethyl-2-oxo-1,2-dihydro-3H-indol-
3-ylidene)-1,3-dithiole-4,5-dicarboxylate (4g) Orange
powder (yield 65%); mp 290–291 °C. IR (KBr) (mmax
/
Dimethyl
2-(1-ethyl-2-oxo-1,2-dihydro-3H-indol-3-yli-
cm-1): 3,446, 2,931, 1,754, 1,664. H NMR (300 MHz,
DMSO-d6): dH (ppm) 1.08 (3H, bs, CH3), 3.64 (2H, bs,
CH2), 3.83 (6H, bs, 2CH3),6.92–7.21 (3H, m, H–Ar Anal.
Calcd for C17H14BrNO5S2: C, 44.74; H, 3.09; N, 3.07.
Found: C, 44.62; H, 3.02; N, 3.19.
1
dene)-1,3-dithiole-4,5-dicarboxylate (4c) Yellow powder
(yield 85%); mp 158–160 °C. IR (KBr) (mmax/cm-1):
1,718, 1,674. H NMR (300 MHz, DMSO-d6): dH (ppm)
1.15 (3H, t, JHH = 7.01 Hz, CH3), 3.75–3.80 (2H, m,
1
3
CH2), 3.87 and 3.88 (6H, s, 2CH3), 7.08–7.24 (4H, m, H–
Ar). 13C NMR (75 MHz, DMSO-d6): dC (ppm) 13.5, 54.3,
54.3, 108.9, 110.2, 120.9, 121.3, 122.1, 127.3, 129.2,
Dimethyl 2-(1-methyl-5-nitro-2-oxoindolin-3-ylidene)-1,3-
dithiole-4,5-dicarboxylate (4h) Yellow powder (yield
123

J IRAN CHEM SOC (2012) 9:333–338
335
75%); mp [300 °C. IR (KBr) (mmax/cm-1): 3,101, 3,028,
1,753, 1,721, 1,669. H NMR (300 MHz, DMSO-d6): dH
80%); mp [300 °C dec. IR (KBr) (mmax/cm-1): 3,237,
2,975, 1,727, 1,681. H NMR (300 MHz, DMSO-d6): dH
1
1
(ppm) 3.80 (3H, s, CH3), 3.89 (6H, s, 2CH3), 7.26–8.16
(3H, m, H–Ar). Anal. Calcd for C16H12N2O7S2: C, 47.05;
H, 2.96; N, 6.86. Found: C, 46.92; H, 2.88; N, 6.76.
(ppm) 1.31 (6H, t, 3JHH = 6.96 Hz, 2CH3), 4.31–4.35 (4H,
m, 2CH2), 7.02–8.10 (3H, m, H–Ar), 11.49 (1H, s, NH).
13C NMR (75 MHz, DMSO-d6): dC (ppm) 14.1, 63.7, 63.8,
108.7, 109.9, 115.5, 119.9, 121.7, 123.6, 130.4, 135.8,
141.9, 144.6, 150.9, 158.6, 159.1, 163.8, 166.5. Anal.
Calcd for C17H14N2O7S2: C, 48.33; H, 3.34; N, 6.63.
Found: C, 44.23; H, 3.25; N, 6.59.
Diethyl 2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-1,3-di-
thiole-4,5-dicarboxylate (4i) Yellow powder (yield 93%);
mp 220 °C. IR (KBr) (mmax/cm-1): 3,231, 2,975, 1,732,
1,665. 1H NMR (300 MHz, DMSO-d6): dH (ppm) 1.27–1.29
(6H, bs, 2CH3), 4.31–4.33 (4H, bs, 2CH2), 6.93–7.27 (4H,
m, H–Ar), 10.84 (1H, s, NH). 13C NMR (75 MHz, DMSO-
d6): dC (ppm) 14.1, 63.6, 110.2, 111.2, 121.5, 121.7, 121.8,
127.5, 129.3, 135.9, 139.5, 145.9, 159.0, 159.7, 163.6, 166.4.
Anal. Calcd for C17H15NO5S2: C, 54.10; H, 4.01; N, 3.71.
Found: C, 54.01; H, 4.10; N, 3.63.
Di-tert-butyl 2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-1,
3-dithiole-4,5-dicarboxylate (4n) Yellow powder (yield
89%); mp [300 °C. dec IR (KBr) (mmax/cm-1): 3,179,
1
2,970, 1,727, 1,666. H NMR (300 MHz, DMSO-d6): dH
(ppm) 1.53 (18H, bs, 6CH3), 6.92–7.31 (4H, m, H–Ar),
10.84 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC
(ppm) 27.9, 85.4, 110.2, 121.5, 121.8, 121.9, 127.4, 130.2,
136.5, 139.4, 146.0, 157.9, 158.5, 166.4. Anal. Calcd for
C21H23NO5S2: C, 58.18; H, 5.35; N, 3.23. Found: C, 58.24;
H, 5.47; N, 3.29.
Diethyl 2-(1-methyl-2-oxo-1,2-dihydro-3H-indol-3-ylidene)-
1,3-dithiole-4,5-dicarboxylate (4j) Yellow powder (yield
90%); mp 169 °C. IR (KBr) (mmax/cm-1): 2,965, 2,923,
1
1,732, 1,707, 1,669. H NMR (300 MHz, DMSO-d6): dH
(ppm) 1.30–1.35 (6H, m, 2CH3), 3.27 (3H, s, CH3),
4.33–4.40 (4H, m, 2CH2), 7.09–7.39 (4H, m, H–Ar). 13C
NMR (75 MHz, DMSO-d6): dC (ppm) 14.0, 14.1, 14.2,
26.4, 63.6, 108.9, 110.1, 120.8, 121.1, 122.2, 127.3, 129.4,
135.9, 140.5, 146.5, 158.9, 159.6, 164.7. Anal. Calcd for
C18H17NO5S2: C, 55.23; H, 4.38; N, 3.58. Found: C, 55.11;
H, 4.31; N, 3.50.
Di-tert-butyl 2-(1-methyl-2-oxo-1,2-dihydro-3H-indol-3-
ylidene)-1,3-dithiole-4,5-dicarboxylate (4o) Orange powder
(yield 85%); mp [300 °C dec. IR (KBr) (mmax/cm-1):
1
2,944, 2,860, 1,729, 1,680. H NMR (300 MHz, DMSO-
d6): dH (ppm) 1.52 (18H, bs, 6CH3), 3.23 (3H, s, CH3),
7.08–7.33 (4H, m, H–Ar). 13C NMR (75 MHz, DMSO-d6):
dC (ppm) 14.0, 23.8, 23.9, 24.0, 24.1, 26.4, 27.1, 27.9, 85.4,
108.9, 109.8, 120.9, 121.2, 122.2, 127.3, 130.4, 136.3,
140.5, 146.7, 157.8, 158.4, 164.9. Anal. Calcd for
C22H25NO5S2: C, 59.04; H, 5.63; N, 3.13. Found: C, 58.92;
H, 5.54; N, 3.04.
Diethyl
2-(1-benzyl-2-oxo-1,2-dihydro-3H-indol-3-yli-
dene)-1,3-dithiole-4,5-dicarboxylate (4k) Yellow powder
(yield 85%); mp 210 °C. IR (KBr) (mmax/cm-1): 3,420,
2,981, 1,737, 1,720, 1,674. H NMR (300 MHz, DMSO-
1
3
d6): dH (ppm) 1.30 (6H, t, JHH = 7.12 Hz, 2CH3),
Di-tert-butyl 2-(5-bromo-2-oxo-1,2-dihydro-3H-indol-3-
ylidene)-1,3-dithiole-4,5-dicarboxylate (4p) Yellow powder
(yield 79%); mp [300 °C dec. IR (KBr) (mmax/cm-1):
3,190, 2,986, 1,721, 1,672, 1,627. 1H NMR (300 MHz,
DMSO-d6): dH (ppm) 1.53 (18H, bs, 6CH3), 6.87–7.36
(3H, m, H–Ar), 10.98 (1H, s, NH). 13C NMR (75 MHz,
DMSO-d6): dC (ppm) 27.9, 85.6, 109.5, 112.0, 113.3,
123.3, 123.8, 129.5, 130.9, 136.3, 138.3, 148.9, 157.9,
158.2, 166.2. Anal. Calcd for C21H22BrNO5S2: C, 49.22;
H, 4.33; N, 2.73. Found: C, 49.14; H, 4.39; N, 2.84.
4.29–4.37 (4H, m, 2CH2), 4.96 (2H, s, CH2Ph), 6.97–7.28
(9H, m, H–Ar). 13C NMR (75 MHz, DMSO-d6): dC (ppm)
14.1, 14.2, 43.2, 63.6, 109.5, 109.8, 121.0, 121.3, 122.4,
127.2, 127.7, 129.0, 129.6, 135.9, 137.1, 139.5, 147.4,
158.9, 159.6, 164.9. Anal. Calcd for C24H21NO5S2: C,
61.65; H, 4.53; N, 3.00. Found: C, 61.72; H, 4.57; N, 2.94.
Diethyl
2-(5-bromo-2-oxo-1,2-dihydro-3H-indol-3-yli-
dene)-1,3-dithiole-4,5-dicarboxylate (4l) Yellow powder
(yield 80%); mp 220 °C. IR (KBr) (mmax/cm-1): 3,231,
1
2,981, 1,734, 1,680. H NMR (300 MHz, DMSO-d6): dH
Dimethyl 2-(2-oxoacenaphthylen-1(2H)-ylidene)-1,3-dithi-
(ppm) 1.24–1.32 (6H, m, 2CH3), 4.30–4.37 (4H, m, 2CH2),
6.87–7.34 (3H, m, H–Ar), 10.97 (1H, s, NH). 13C NMR
(75 MHz, DMSO-d6): dC (ppm) 14.2, 16.0, 63.6, 63.7,
66.2, 85.6, 109.8, 112.0, 113.4, 123.3, 123.7, 129.6, 130.1,
135.6, 138.4, 148.8, 158.9, 159.5, 166.1, 173.0. Anal.
Calcd for C17H14BrNO5S2: C, 44.74; H, 3.09; N, 3.07.
Found: C, 44.65; H, 3.01; N, 3.12.
ole-4,5-dicarboxylate (8a) Orange powder (yield 96%);
1
mp 198 °C. IR (KBr) (mmax/cm-1): 17.15, 1,669. H NMR
(300 MHz, DMSO-d6): dH (ppm) 3.88 and 3.90 (6H, s,
2CH3), 7.41–8.14 (6H, m, H–Ar). Anal. Calcd for
C19H12O5S2: C, 59.36; H, 3.15. Found: C, 59.43; H, 3.08.
(Due to very low solubility of the product 8a, we cannot
report the 13C NMR data for this product).
Diethyl 2-(5-nitro-2-oxo-1,2-dihydro-3H-indol-3-ylidene)-
Diethyl 2-(2-oxoacenaphthylen-1(2H)-ylidene)-1,3-dithi-
1,3-dithiole-4,5-dicarboxylate (4m) Yellow powder (yield
ole-4,5-dicarboxylate (8b) Yellow powder (yield 94%);
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J IRAN CHEM SOC (2012) 9:333–338
mp 164 °C. IR (KBr) (mmax/cm-1): 3,425, 1,718, 1,653. 1H
NMR (300 MHz, DMSO-d6): dH (ppm) 1.23–1.30 (6H, m,
2CH3), 4.29–4.33 (4H, m, 2CH2),7.18–8.02 (6H, m, H–Ar).
13C NMR (75 MHz, DMSO-d6): dC (ppm) 14.0, 14.1, 63.5,
63.7, 118.6, 119.2, 122.2, 124.7, 128.5, 128.8, 128.9,
129.0, 129.2, 130.0, 131.8, 132.4, 132.6, 132.7, 135.5,
135.7, 145.9, 158.8, 159.6, 187.5. Anal. Calcd for
C21H16O5S2: C, 61.15; H, 3.91. Found: C, 61.04; H, 3.86.
Diethyl 2-(1,3-dimethyl-2,4,6-trioxotetrahydropyrimi-
din-5(6H)-ylidene)-1,3-dithiole-4,5-dicarboxylate (10b)
Cream powder (yield 87%); mp 184 °C. IR (KBr) (mmax
/
cm-1): 2,975, 2,928, 1,733, 1,633. H NMR (300 MHz,
DMSO-d6): dH (ppm) 1.30 (6H, t, 3JHH = 7.04 Hz, 2CH3),
3.20 (6H, bs, 2CH3), 4.48 and 4.35 (4H, ABq,
3JHH = 6.98 Hz, 2CH2). 13C NMR (75 MHz, DMSO-d6):
dC (ppm) 14.1, 28.3, 63.7, 103.1, 136.4, 150.5, 159.3,
160.7, 173.1. Anal. Calcd for C15H16N2O7S2: C, 44.99; H,
4.03; N, 7.00. Found: C, 44.90; H, 4.09; N, 6.91.
1
Di-tert-butyl 2-(2-oxoacenaphthylen-1(2H)-ylidene)-1,3-
dithiole-4,5-dicarboxylate (8c) Yellow powder (yield
85%); mp [300 °C. IR (KBr) (mmax/cm-1): 3,425,
Di-tert-butyl 2-(1,3-dimethyl-2,4,6-trioxotetrahydropyrimi-
1
1,720,1,674, 1,612. H NMR (300 MHz, DMSO-d6): dH
din-5(6H)-ylidene)-1,3-dithiole-4,5-dicarboxylate
(10c)
(ppm) 1.57 (18H, s, 6CH3), 7.48–8.13 (6H, m, H–Ar). 13C
NMR (75 MHz, DMSO-d6): dC (ppm) 28.1, 85.5, 119.3,
122.2, 124.8, 128.6, 129.0, 130.3, 131.9. Anal. Calcd for
C25H24O5S2: C, 64.08; H, 5.16. Found: C, 63.98; H, 5.08.
Cream powder (yield 80%); mp [300 °C. IR (KBr) (mmax
/
cm-1): 2,975, 2,939, 1,720, 1,717, 1,634. 1H NMR
(300 MHz, DMSO-d6): dH (ppm) 1.54 (18H, s, 6CH3), 3.32
(6H, s, 2CH3). Anal. Calcd for C19H24N2O7S2: C, 49.99; H,
5.30; N, 6.14. Found: C, 49.83; H, 5.22; N, 6.05. (Due to
very low solubility of the product 10c, we cannot report the
13C NMR data for this product).
Dimethyl 2-(1,3-dioxo-1H-inden-2(3H)-ylidene)-1,3-di-
thiole-4,5-dicarboxylate (9a) Yellow powder (yield
80%); mp [300 °C. IR (KBr) (mmax/cm-1): 1,706, 1,664.
1H NMR (300 MHz, DMSO-d6): dH (ppm) 3.89 (6H, s,
2CH3), 7.77 (4H, bs, H–Ar). 13C NMR (75 MHz, DMSO-
d6): dC (ppm) 54.5, 122.9, 134.7, 135.2, 140.2, 159.5,
186.9. Anal. Calcd for C16H10O6S2: C, 53.03; H, 2.78.
Found: C, 53.11; H, 2.71.
Results and discussion
We found that a mixture of dialkyl acetylenedicarboxylate
1, carbon disulfide 2 and isatins 3 in the presence of trib-
uthylposphine in CH2Cl2 at room temperature, afforded
oxoindolin-3-ylidene-1,3-dithioles 4 in good yields for
3–18 h. The results are summarized in Table 1.
Diethyl 2-(1,3-dioxo-1H-inden-2(3H)-ylidene)-1,3-dithiole-
4,5-dicarboxylate (9b) Yellow powder (yield 72%); mp
[300 °C dec. IR (KBr) (mmax/cm-1): 3,430, 2,981, 1,725,
1,659. 1H NMR (300 MHz, DMSO-d6): dH (ppm) 1.30
The good yields and purity of products and simplic-
ity of the present procedure makes it an interesting,
3
3
(6H, t, JHH = 7.09 Hz, 2CH3), 4.34 (4H, q, JHH
=
7.07 Hz, 2CH2), 7.74 (4H, bs, H–Ar), 11.49 (1H, s, NH).
13C NMR (75 MHz, DMSO-d6): dC (ppm) 14.1, 63.8,
115.6, 122.9, 134.7, 135.2, 140.1, 159.0, 162.0, 186.9.
Anal. Calcd for C18H14O6S2: C, 55.37; H, 3.61. Found: C,
55.29; H, 3.36.
Table 1 Synthesis of oxoindolin-3-ylidene-1,3-dithioles 4
Compound 4
R
X
R1
Time (h)
Yield (%)a
a
b
c
d
e
f
Me
Me
Me
Me
Me
Me
Me
Me
Et
H
H
3
3
98
94
85
91
83
86
65
78
93
90
85
80
80
89
85
79
Di-tert-butyl 2-(1,3-dioxo-1H-inden-2(3H)-ylidene)-1,3-
dithiole-4,5-dicarboxylate (9c) Yellow powder (yield
70%); mp [300 °C. IR (KBr) (mmax/cm-1): 2,986, 2,928,
H
Me
Et
H
3.5
5
H
PhCH2
H
1
1,718, 1,715, 1,672. H NMR (300 MHz, DMSO-d6): dH
Br
NO2
Br
NO2
H
13
12
15
13
4
(ppm) 1.55 (18H, s, 6CH3), 7.80 (4H, bs, H–Ar). 13C NMR
(75 MHz, DMSO-d6): dC (ppm) 27.9, 85.9, 122.9, 135.2,
135.5, 140.2, 157.8, 187.0. Anal. Calcd for C22H22O6S2: C,
59.17; H, 4.97. Found: C, 59.23; H, 4.89.
H
g
h
i
Et
Me
H
j
Et
H
Me
PhCH2
H
6
Dimethyl
2-(1,3-dimethyl-2,4,6-trioxotetrahydropyrimi-
(10a)
k
l
Et
H
7
din-5(6H)-ylidene)-1,3-dithiole-4,5-dicarboxylate
Et
Br
NO2
H
15
16
5
Cream powder (yield 91%); mp 210 °C. IR (KBr) (mmax
/
m
n
o
p
Et
H
cm-1): 1,737, 1,716, 1,701. 1H NMR (300 MHz, DMSO-d6):
dH (ppm) 3.31 (3H, s, CH3), 3.90 (3H, s, CH3) 13C NMR
(75 MHz, DMSO-d6): dC (ppm) 21.5, 23.8, 28.3, 54.4, 136.4,
150.5, 159.7, 160.7, 173.2. Anal. Calcd for C13H12N2O7S2:
C, 41.93; H, 3.25; N, 7.52. Found: C, 41.85; H, 3.33; N, 7.60.
tBu
tBu
tBu
H
H
Me
H
8
Br
18
a
Isolated yields
123

J IRAN CHEM SOC (2012) 9:333–338
337
Scheme 2 Synthesis of 1,3-
dithioles 8, 9 and 10
O
O
CO2R
S
CO2R
O
S
5
R: Me 8a 96%
Et 8b 94%
tBu 8c 85%
O
O
O
O
OR
+
O
CO2R
CO2R
O
CH2Cl2, r.t.
S
S
6
R: Me 9a 80%
Et 9b 72%
tBu 9c 70%
CS2
Bu3P
6 h
O
O
O
OR
NMe
O
MeN
1
2
O
Me
CO2R
CO2R
O
N
N
R: Me 10a 91%
Et 10b 87%
tBu 10c 80%
S
7
O
S
O
Me
Scheme 3 Proposed
mechanism
Bu3P + CS2
O
RO2C
S
S
PBu3
S
RO2C
4
RO2C
CO2R
S
S
Bu3P
S
3, 5, 6 or 7
RO2C
CO2R
1
RO2C
S
PBu3
4, 8, 9 or 10
S
RO2C
convenient and acceptable one-pot method for the prep-
aration of functionalized oxoindolin-3-ylidene-1,3-dithi-
oles. In addition, the workup of these very clean reactions
involves only a filtration and simple washing step with
ether.
We have not established an exact mechanism for the
formation of 1,3-dithioles 4, 8, 9 and 10, however, a rea-
sonable possibility is shown in Scheme 3.
Conclusion
As expected, when the isatin 3 was replaced by
acenaphthylene-1,2-dione 5, ninhydrine 6 and 1,3-dimethyl-
pyrimidine-tetraone 7, 2-(2-oxoacenaphthylen-1(2H)-yli-
dene)-1,3-dithioles 8, 2-(1,3-dioxo-1H-inden-2(3H)-ylidene)
-1,3-dithioles 9 and 2-(2,4,6-trioxotetrahydropyrimidin-5
(6H)-ylidene)-1,3-dithioles 10 were obtained, respectively, in
good to excellent yields under the same reaction conditions
(Scheme 2). When acenaphthylene-1,2-dione 5 was used, due
to sterically hindered, only mono dithiol derivatives 8a-c were
produced and another carbonyl group remained unreacted.
Despite several active aldehydes and ketones in 1,3-dithioles
synthesis [7–10], utilization of isatins, acenaphthylene-1,2-
dione, ninhydrine and pyrimidine-tetraone have not been
reported yet.
In conclusion, we have described a mild, facile and
three-component method for the synthesis of oxoindolin-yli-
dene-1,3-dithioles, oxoacenaphthylen-ylidene-1,3-dithioles,
dioxo-inden-ylidene-1,3-dithioles and trioxotetrahydropyr-
imidin-ylidene-1,3-dithioles using readily available starting
materials. Prominent among the advantages of this new
methodare operationalsimplicity, goodyieldsand easywork-
up procedures employed.
Acknowledgments We gratefully acknowledge financial support
from the Research Council of Shahid Beheshti University.
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