Synthesis and properties of 4-substituted 5H-1,2,3-dithiazol-5-ylidenes

Article abstract of DOI:10.1007/s11172-010-0029-z

Substituted ethanone oximes react with S₂Cl₂ and pyridine to give 1,2,3-dithiazolium chlorides. The treatment of these products with malonodinitrile in dichloromethane affords 4-substituted 5 H-1,2,3-dithiazol-5-ylidenes. The reactio

Full text of DOI:10.1007/s11172-010-0029-z

Russian Chemical Bulletin, International Edition, Vol. 58, No. 2, pp. 437—441, February, 2009
437
Synthesis and properties of 4ꢀsubstituted 5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidenes*
V. V. Popov, O. I. Bol´shakov, L. S. Konstantinova, and O. A. Rakitin
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Еꢀmail: orakitin@ioc.ac.ru
Substituted ethanone oximes react with S2Cl2 and pyridine to give 1,2,3ꢀdithiazolium
chlorides. The treatment of these products with malonodinitrile in dichloromethane affords
4ꢀsubstituted 5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidenes. The reaction of the latter compounds with
nꢀbutylamine unexpectedly yielded addition products at one of the nitrile groups, viz. substiꢀ
tuted 1,2,3ꢀdithiazolꢀ5ꢀylideneethanimidamides.
Key words: 1,2,3ꢀdithiazoles, synthesis, ethanone oximes, sulfur monochloride, malonoꢀ
dinitrile, ethanimidamides.
Derivatives of monocyclic nonꢀfused 1,2,3ꢀdithiazoles
are of great interest as herbicides, compounds exhibiting
cytotoxic or cytostatic activity, and precursors of molecuꢀ
lar semiconductors.1 1,2,3ꢀDithiazoles containing the
chlorine atom at position 4 are known and well studied.
Various derivatives, including ketone 2, thione 3, imines
4, and ylidenes 5, were synthesized based on 4,5ꢀdichloroꢀ
5Hꢀ1,2,3ꢀdithiazolium chloride 1 (Scheme 1), and these
compounds were used for the synthesis of a wide range of
functional derivatives.1,2
compounds would be expected to have radically different
chemical and biological properties due to the absence
of the good leaving chlorine atom. Recently, we have
developed a general procedure for the synthesis of 4ꢀsubꢀ
stituted 1,2,3ꢀdithiazoles by the reaction of readily availꢀ
able ethanone oximes with sulfur monochloride and
synthesized a wide range of various ketones, thiones, and
imino derivatives of these heterocycles.3 In the present
study, we examined the possibility of synthesizing 4ꢀsubꢀ
stituted 5ꢀylideneꢀ1,2,3ꢀdithiazoles and investigated
selected chemical properties of the reaction products.
Previously, it has been shown3 that ethanone oximes 6
react with S2Cl2 to give 4ꢀsubstituted 1,2,3ꢀdithiazolium
chlorides. It was found that the highest yields of the products
were achieved with the use of ethanone oxime 6, sulfur
monochloride, and pyridine in a ratio of 1 : 2 : 3. At the same
time it was found that salts 6 are insufficiently stable and
decompose with time. Hence, we decided to perform the
in situ reactions of these compounds with Cꢀnucleophiles.
As a model transformation, we chose the reaction of
acetophenone oxime 6а with S2Cl2 followed by the treatꢀ
ment with malonodinitrile as the Cꢀnucleophile containing
the active methylene fragment (Scheme 2).
It should be noted that other 4ꢀsubstituted 1,2,3ꢀdiꢀ
thiazoles were hitherto virtually unknown. However, these
Scheme 1
It appeared that the reaction afforded the target product
8а along with 4ꢀphenylꢀ1,2,3ꢀdithiazoleꢀ5ꢀthione (9а) as
the byꢀproduct. With the aim of finding the optimal conꢀ
ditions for the reaction of salt 7а with malonodinitrile, we
varied the reagent ratio, the temperature, and the reaction
time. All three factors were found to influence the yield
of the target product 8а. The main results are presented
in Table 1.
B is a base.
The introduction of three equivalents of malonoꢀ
dinitrile and the performance of the reaction at low
temperature made it possible to suppress, to a certain
* On the occasion of the 75th anniversary of the foundation
of the N. D. Zelinsky Institute of Organic Chemistry of the
Russian Academy of Sciences.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 429—432, February, 2009.
1066ꢀ5285/09/5802ꢀ0437 © 2009 Springer Science+Business Media, Inc.

438
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 2, February, 2009
Popov et al.
Scheme 2
reaction (the mechanism was described in the publicaꢀ
tion4). Under these conditions, the activity of this sulfurꢀ
containing nucleophile is evidently comparable to the
nucleophilicity of malonodinitrile.
We extended the aboveꢀdescribed conditions to a
series of ethanone oximes and showed that, in most cases,
these reactions afford 1,2,3ꢀdithiazolꢀ5ꢀylidenes although,
as a rule, in low yields (Scheme 3). These transformations
give the corresponding thiones 9 as byꢀproducts.
Scheme 3
Table 1. Reaction conditions and the yields of the reaction
products of 1ꢀphenylethanone oxime (10 mmol) with S2Cl2
(20 mmol), pyridine (30 mmol), and malonodinitrile
Run
Conditions
Yield (%)
CH2(CN)2
/mmol
T/°C
t/min
8а
9а
1
2
3
4
5
6
7
8
9
10
10
10
10
10
30
30
30
50
50
100
–5
–5
–5
–20
–5
–20
–20
–15
–15
–15
30
60
90
60
30
60
90
60
90
90
7
7
8
5
8
40
37
33
28
33
23
25
27
27
27
Comꢀ
pound 8
a
b
c
R
Yield
(%)
17
14
14
Comꢀ
pound 8
R
Yield
(%)
12
8
Ph
d
e
2ꢀthienyl
Me
4ꢀFC6H4
4ꢀMeOC6H4
23
11
17
17
16
It should be noted that Appel’s salt 1 containing the
electronꢀwithdrawing chlorine atom at position 4 does
not react with malonodinitrile even at 0 °C. An increase
in the reaction temperature to room temperature results
in the slow formation of thione 3.
extent, the competitive reaction giving rise to thione; howꢀ
ever, at –20 °C malonodinitrile also exhibits low activity,
as evidenced by the low yields of the target ylidene. Neverꢀ
theless, we succeeded in partially suppressing the comꢀ
petitive reaction giving rise to thione 9а and increased
the yield of ylidene 8а from 7% to 17% by increasing the
amount of malonodinitrile in the reaction mixture to
the fivefold excess and keeping the reaction mixture at
–15 °C for 1 h. However, an increase in the amount
of malonodinitrile to the tenfold excess and the storage of
the reaction mixture during a longer time (1.5 h) did not
allow us to obtain the target product in higher yield. As
can be seen from Table 1, the total yield of products 8а
and 9а remains virtually constant regardless of the reacꢀ
tion conditions, which apparently indicates that the
reactions yielding both products are competitive.
It is known1,2 that the most characteristic reactions of
4ꢀchloroꢀ1,2,3ꢀdithiazolꢀ5ꢀylidenes are reactions with
nucleophilic reagents and reagents with high basicity,
which, as a rule, are accompanied by the ring opening and
elimination of the chlorine atom as the chloride anion
giving rise to the nitrile group. Thus, the reactions of
(4ꢀchloroꢀ5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene)cyanoacetates 10
with primary and secondary amines produce (Z)ꢀ3ꢀalkylꢀ
aminoꢀ2,3ꢀdicyanoacrylates 11 in yields from moderate
to high.5 The formation of these compounds can be
attributed to the nucleophilic attack of the alkylamine on
the carbon atom C(5) of the dithiazole ring accompanied
by the elimination of S2 and HCl and the formation of the
stable nitrile group (Scheme 4).
Thione 9а is produced in the reaction of salt 7а with
the sulfurꢀcontaining nucleophile. The latter is formed
from the base (pyridine), which is present in the reaction
mixture, and S8, which is generated in the course of the
The behavior of trifluoroacetylidene derivatives of
1,2,3ꢀdithiazoles in the reactions with alkylamines someꢀ
what differs from the aboveꢀconsidered reaction. Thus,
these derivatives form dihydroaminopyrroles (22—55%)

4ꢀSubstituted 5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidenes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 2, February, 2009
439
Scheme 4
This reaction pathway is unusual because only one
example of the analogous addition of amine to the
dicyanomethylene group is known,6 whereas amidines 12
are generally synthesized in a more complex way.
Experimental
The 1H NMR spectra (in CDCl3) were recorded on a Bruker
AMꢀ300 instrument operating at 300 MHz; the 13C NMR
spectra were measured on a Bruker AMꢀ300 instrument operatꢀ
ing at 75.5 MHz. The chemical shifts are given on the δ scale
with respect to SiMe4. The melting points were determined on a
Kofler hotꢀstage apparatus and are uncorrected. The electronꢀ
impact mass spectra were obtained on a Finnigan MAT INCOS 50
instrument (70 eV). The IR spectra were recorded on a Specord
M80 instrument in KBr pellets.
The starting ethanone oximes 6a—e were synthesized
according to the general procedure.7 The melting points and the
spectroscopic characteristics of substituted 5Hꢀ1,2,3ꢀdithiazoleꢀ
5ꢀthiones 9а,b,d,e are similar to those described previously.3
Synthesis of 4ꢀsubstituted 5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylideneꢀ
malononitriles (general procedure). Sulfur monochloride
(0.32 mL, 4 mmol) and pyridine (0.48 mL, 6 mmol) were
successively added dropwise to a solution of ethanone oxime 6
(2 mmol) in dichloromethane (15 mL) at –7 °C under argon.
The reaction mixture was kept at –2 °C for 20 min, a solution
of malonodinitrile (0.66 g, 10 mmol) in acetonitrile (10 mL) was
added dropwise at –15 °C, and the reaction mixture was stirred
for 1 h. Then pyridine (0.32 mL, 4 mmol) was added dropwise
at –15 °C, the temperature was raised to room temperature,
and the reaction mixture was concentrated. The residue was
chromatographed on a silica gel column (Silicagel Merck 60,
CH2Cl2—petroleum ether mixture as the eluent).
R1 = Me, Et
R2, R3 = H, Me, Et, Pr, Bu, Pri, But, allyl, nꢀpentyl
with primary amines and dihydroiminofurans (18—62%)
with secondary amines.5 However, it is hypothesized that
cyanoenamino ketones analogous to (Z)ꢀ3ꢀalkylaminoꢀ
2,3ꢀdicyanoacrylates 11 are the key intermediates in these
reactions.
We studied the reactions of ylidenes 8 with diethylꢀ
amine and butylamine. The reactions of ylidenes 8 with
diethylamine in chloroform at room temperature were
found to afford a series of unstable products, which we
failed to isolate and identify.
The reactions of all ylidenes under investigation
(8a—e) with primary butylamine instead of diethylamine
afford one product in moderate yields. We found that two
equivalents of amine are necessary for the reaction to
proceed. The mass spectra of the reaction products have
molecular ion peaks with the mass equal to the sum of the
molecular masses of the starting compounds. This fact
indicates that these compounds are addition products of
the primary amine molecule to dithiazole 8. The NMR
spectra show signals of the dithiazole ring, the correspondꢀ
ing substituents R, and the nitrile group (δ 115—116),
whose presence is confirmed also by the presence of the
characteristic band (ν 2200—2210 cm–1) in the IR specꢀ
trum. Therefore, the reaction proceeds as the addition of
the amine molecule to the nitrile group to form the correꢀ
sponding monoamidines 12 (Scheme 5) rather than
according to the mechanism known for 1,2,3ꢀdithiazoles,
which involves the ring opening.
2ꢀ(4ꢀPhenylꢀ5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene)malononitrile (8a).
The yield was 17%, Rf = 0.68 (CH2Cl2). Orange crystals,
m.p. 215—217 °C. Found (%): C, 54.68; H, 2.31; N, 16.91;
S, 26.29. C11H5N3S2. Calculated (%): C, 54.30; H, 2.07;
N, 17.27; S, 26.36. IR, ν/cm–1: 2924, 2852 (C—H), 2216 (CN),
1468, 1280, 1096, 812, 748.1H NMR (CDCl3), δ: 7.59 (m, 5 H,
Ph). 13C NMR (CDCl3), δ: 60.8 (C(CN)2); 111.7 (CN); 117.7
(CN); 128.5 (2 CHPh); 129.4 (2 CHPh); 130.8 (CHPh); 131.0;
161.9; 174.0 (3 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 243 [M]+
(57), 179 (35), 135 (90), 103 (100), 77 (100).
4ꢀPhenylꢀ5Hꢀ1,2,3ꢀdithiazoleꢀ5ꢀthione (9a). The yield was
27%, Rf = 0.93 (CH2Cl2).
2ꢀ[4ꢀ(4ꢀFluorophenyl)ꢀ5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene]ꢀ
malononitrile (8b). The yield was 14%, Rf = 0.73 (CH2Cl2).
Orange crystals, m.p. 224—226 °C. Found (%): C, 50.49;
H, 1.50; N, 16.12. C11H4FN3S2. Calculated (%): C, 50.65;
H, 1.54; N, 15.88. IR, ν/cm–1: 2920 (C—H), 2208 (CN), 1608,
1516, 1448, 1286, 1228, 1164, 1020, 880, 848, 784, 668.
1H NMR (CDCl3), δ: 7.23 (t, 2 H, Ar, J = 8.8 Hz); 7.51 (m,
2 H, Ar). 13C NMR (CDCl3), δ: 60.7 (C(CN)2); 111.8 (CN);
115.7 (2 CH); 117.6 (CN); 132.1 (2 CH); 127.5; 161.0; 165.2;
174.4 (4 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 273 [M]+ (80),
209 (32), 165 (80), 133 (75), 108 (60).
Scheme 5
Comꢀ
pound 12
a
b
c
R
Yield
(%)
42
Comꢀ
pound 12
R
Yield
(%)
39
4ꢀ(4ꢀFluorophenyl)ꢀ5Hꢀ1,2,3ꢀdithiazoleꢀ5ꢀthione (9b). The
yield was 30%, Rf = 0.92 (CH2Cl2).
2ꢀ[4ꢀ(4ꢀMethoxyphenyl)ꢀ5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene]ꢀ
malononitrile (8c). The yield was 14%, Rf = 0.60 (CH2Cl2).
Ph
d
e
2ꢀthienyl
Me
4ꢀFC6H4
4ꢀMeOC6H4
35
57
42

440
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 2, February, 2009
Popov et al.
Orange crystals, m.p. 167—169 °C. Found (%): C, 52.95;
H, 2.76; N, 15.35. C12H7N3OS2. Calculated (%): C, 52.73;
H, 2.58; N, 15.03. IR, ν/cm–1: 3020 and 2928 (C—H), 2196
164.5 (5 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 316 [M]+ (7),
273 (80), 244 (8), 180 (7), 103 (25), 77 (80).
NꢀButylꢀ2ꢀcyanoꢀ2ꢀ[4ꢀ(4ꢀfluorophenyl)ꢀ1,2,3ꢀdithiazolꢀ
5ꢀylidene]ethanimidamide (12b). The yield was 35%. Yellow
crystals, m.p. 88—90 °C. Found (%): C, 54.13; H, 4.63;
N, 16.46. C15H15FN4S2. Calculated (%): C, 53.87; H, 4.52;
N, 16.75. IR, ν/cm–1: 3316 and 3272 (NH), 3080, 2960, 2928,
2856 (CH), 2207 (CN), 1604, 1556, 1504, 1440, 1236, 1164,
1004, 836, 804, 716, 676. 1H NMR (CDCl3), δ: 0.97 (t, 3 H,
CH3, J = 7.3 Hz); 1.45 (m, 2 H, CH2); 1.67 (m, 2 H, CH2); 3.48
(m, 2 H, CH2); 7.19 (t, 2 H, Ar, J = 8.1 Hz); 7.76 (m, 2 H, Ar);
8.11 (s, 1 H, NH); 8.44 (s, 1 H, NH). 13C NMR (CDCl3), δ:
13.8 (CH3); 20.2 (CH2); 31.5 (CH2); 42.5 (CH2); 116.1 (2 CH,
Ar); 116.6 (CN); 129.1 (2 CH, Ar); 133.7, 154.2, 162.5, 163.5,
164.5, 165.8 (6 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 334 [M]+
(15), 291 (100), 262 (5), 121 (25), 95 (25).
NꢀButylꢀ2ꢀcyanoꢀ2ꢀ[4ꢀ(4ꢀmethoxyphenyl)ꢀ1,2,3ꢀdithiazolꢀ
5ꢀylidene]ethanimidamide (12с). The yield was 42%. Yellow
crystals, m.p. 48—50 °C. Found (%): C, 55.75; H, 5.42;
N, 15.85. C16H18N4OS2. Calculated (%): C, 55.47; H, 5.24;
N, 16.17. IR, ν/cm–1: 3196 (NH), 2956, 2928, 2860 (CH), 2201
(CN), 1608, 1564, 1512, 1440, 1316, 1176, 1140, 1036, 1000,
832, 812, 780, 680. 1H NMR (CDCl3), δ: 0.97 (t, 3 H, CH3,
J = 7.3 Hz); 1.44 (m, 2 H, CH2); 1.67 (m, 2 H, CH2); 3.47 (m,
2 H, CH2); 3.88 (s, 3 H, MeO); 7.00 (d, 2 H, Ar, J = 8.8 Hz);
7.71 (d, 2 H, Ar, J = 8.8 Hz); 8.12 (t, 1 H, NH, J = 4.5 Hz); 8.39
(s, 1 H, NH). 13C NMR (CDCl3), δ: 13.9 (CH3); 20.2 (CH2);
31.6 (CH2); 42.6 (CH2); 55.3 (MeO); 116.7 (CN); 114.3 (2 CH,
Ar); 128.6 (2 CH, Ar); 110.1; 130.4, 154.9, 161.6, 163.5, 165.0
(6 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 346 [M]+ (20), 303
(60), 274 (9), 133 (60), 108 (40).
NꢀButylꢀ2ꢀcyanoꢀ2ꢀ(4ꢀthiophenꢀ2ꢀylꢀ1,2,3ꢀdithiazolꢀ
5ꢀylidene)ethanimidamide (12d). The yield was 39%. Yellow
crystals, m.p. 57—59 °C. Found (%): C, 48.20; H, 4.57;
N, 17.59. C13H14N4S3. Calculated (%): C, 48.42; H, 4.38;
N, 17.37. IR, ν/cm–1: 3268 and 3224 (NH), 3076, 2956, 2928
(CH), 2204 (CN), 1720, 1672, 1532, 1444, 1366, 1292, 1172,
1080, 920, 856, 816, 708. 1H NMR (CDCl3), δ: 0.98 (t, 3 H,
CH3, J = 7.3 Hz); 1.45 (m, 2 H, CH2); 1.68 (m, 2 H, CH2);
3.50 (m, 2 H, CH2); 7.14 (m, 1 H, thienyl); 7.51 (d, 1 H,
thienyl, J = 5.1 Hz); 7.65 (d, 1 H, thienyl, J = 3.7 Hz) 8.14 (s,
1 H, NH); 8.45 (s, 1 H, NH). 13C NMR (CDCl3), δ: 13.8
(CH3); 20.2 (CH2); 31.5 (CH2); 42.5 (CH2); 125.2 (CN); 126.9,
127.9, and 129.7 (3 CH, thienyl); 116.6; 141.5, 148.8, 153.7,
163.4, 164.4 (6 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 332 [M]+
(25), 279 (100), 250 (7), 109 (30), 83 (20).
NꢀButylꢀ2ꢀcyanoꢀ2ꢀ(4ꢀmethylꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene)ꢀ
ethanimidamide (11e). The yield was 52%. Yellow crystals,
m.p. 39—41 °C. Found (%): C, 47.50; H, 5.76; N, 21.75.
C10H14N4S2. Calculated (%): C, 47.22; H, 5.55; N, 22.03. IR,
ν/cm–1: 3200 (NH), 2952, 2928, 2856 (CH), 2210 (CN), 1696,
1596, 1520, 1456, 1376, 1280, 1180, 1084, 1024, 864, 812, 732,
624. 1H NMR (CDCl3), δ: 0.95 (t, 3 H, CH3, J = 7.3 Hz); 1.43
(m, 2 H, CH2); 1.65 (m, 2 H, CH2); 2.49 (s, 3 H, CH3); 3.46 (m,
2 H, CH2); 7.98 (s, 1 H, NH); 8.34 (s, 1 H, NH). 13C NMR
(CDCl3), δ: 13.9 (CH3); 20.3 (CH3); 24.3 (CH2); 31.6 (CH2);
42.5 (CH2); 115.8 (CN); 114.1; 153.8; 155.9; 163.6; 164.9
(5 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 254 [M]+ (35), 211
(100), 182 (15), 41 (25).
(CN), 1608, 1516, 1468, 1444, 1416, 1264, 1184, 1028, 808 cm–1
.
1H NMR (CDCl3), δ: 3.78 (s, 3 H, MeO); 7.01 (d, 2 H, 2 CH,
J = 8.8 Hz); 7.47 (d, 2 H, 2 CH, J = 8.8 Hz). 13C NMR (CDCl3),
δ: 55.4 (CH3); 60.9 (C(CN)2); 111.8 (CN); 117.8 (CN); 113.9
(2 CH, Ar); 131.1 (2 CH, Ar); 123.0; 161.1; 161.9; 174.4
(4 Cquat). MS (EI, 70 eV), m/z (Irel (%)): 273 [M]+ (30), 209
(15), 133 (55), 108 (45).
4ꢀ(4ꢀMethoxyphenyl)ꢀ5Hꢀ1,2,3ꢀdithiazoleꢀ5ꢀthione (8с).
The yield was 30%, Rf = 0.89 (CH2Cl2). Paleꢀbrown crystals,
m.p. 68—71 °C. Found (%): C, 44.95; H, 3.08; N, 6.04.
C9H7NOS3. Calculated (%): C, 44.79; H, 2.92; N, 5.80.
1H NMR (CDCl3), δ: 3.87 (s, 3 H, CH3); 6.98 (d, 2 H, 2 CH,
J = 8.8 Hz), 8.98 (d, 2 H, 2 CH, J = 8.8 Hz). 13C NMR
(CDCl3), δ: 55.4 (CH3); 113.5 (2 CH, Ar); 123.9 (2 CH, Ar);
131.1; 161.4; 167.3 (3 Cquat); 208.4 (C=S). MS (EI, 70 eV), m/z
(Irel (%)): 241 M+ (28), 210 (15), 197 (4), 133 (100).
2ꢀ(4ꢀThiophenꢀ2ꢀylꢀ5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene)malonoꢀ
nitrile (8d). The yield was 12%, Rf = 0.58 (CH2Cl2). Brown
crystals, m.p. 160—162 °C. Found (%): C, 43.31; H, 1.16;
N, 16.80. C9H3N3S3. Calculated (%): C, 43.66; H, 1.31; N, 16.45.
IR, ν/cm–1: 3096, 2924 (C—H), 2204 (CN), 1632, 1444, 1244,
1
1052, 886, 828, 720, 668 cm–1. H NMR (CDCl3), δ: 7.16 (m,
1 H, thienyl); 7.48 (d, 1 H, thienyl, J = 4.8 Hz); 7.84 (d, 1 H,
thienyl, J = 5.1 Hz). 13C NMR (CDCl3), δ: 60.0 (C(CN)2);
111.5 (CN); 117.6 (CN); 132.0, 130.7 and 127.3 (3 CH, thienyl);
134.9; 174.1 and 155.4 (3 Cquat). MS (EI, 70 eV), m/z (Irel (%)):
249 [M]+ (87), 222 (15), 185 (35), 141 (98), 109 (72), 82 (37).
4ꢀ(2ꢀThienyl)ꢀ5Hꢀ1,2,3ꢀdithiazoleꢀ5ꢀthione (9d). The yield
was 28%, Rf = 0.90 (CH2Cl2).
2ꢀ(4ꢀMethylꢀ5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene)malononitrile (8e).
The yield was 23%, Rf = 0.70 (CH2Cl2). Paleꢀorange crystals,
m.p. 150—152 °C. Found (%): C, 39.71; H, 1.69; N, 23.16.
C6H3N3S2. Calculated (%): C, 40.11; H, 1.87; N, 22.88. IR,
ν/cm–1: 2920 (CH), 2212 (CN), 1456, 1376, 1272, 1200, 1028,
964, 932, 892, 788, 668 cm–1 1H NMR (CDCl3), δ: 2.86 (s,
.
3 H, CH3). 13C NMR ((CDCl3), δ: 20.3 (CH3); 64.1 (C(CN)2);
112.7 (CN); 116.5 (CN); 160.3 and 173.9 (2 Cquat). MS (EI,
70 eV), m/z (Irel (%)): 181 [M]+ (27), 73 (100), 64 (45), 46 (22).
4ꢀMethylꢀ5Hꢀ1,2,3ꢀdithiazoleꢀ5ꢀthione (9е). The yield was
18%, Rf = 0.95 (CH2Cl2).
Synthesis of Nꢀbutylꢀ2ꢀcyanoꢀ2ꢀ(4ꢀRꢀ1,2,3ꢀdithiazolꢀ5Hꢀ
ylidene)acetamidines 12 (general procedure). nꢀButylamine
(0.2 mL, 2 mmol) was added dropwise to a solution of ylidene 8
(1 mmol) in chloroform (30 mL) at room temperature under
argon. The reaction mixture was stirred for 2 h and then
chromatographed on a silica gel column (Silicagel Merck 60,
CH2Cl2 as the eluent).
NꢀButylꢀ2ꢀcyanoꢀ2ꢀ(4ꢀphenylꢀ1,2,3ꢀdithiazolꢀ5ꢀylidene)ꢀ
ethanimidamide (12а). The yield was 42%. Yellow crystals,
m.p. 94—96 °C. Found (%): C, 57.23; H, 5.29; N, 17.35.
C15H16N4S2. Calculated (%): C, 56.93; H, 5.10; N, 17.70.
IR, ν/cm–1: 3628 and 3212 (NH), 2956, 2928, 2852 (CH),
2206 (CN), 1596, 1448, 1336, 1280, 1196, 872, 740, 700 cm–1
.
1H NMR (CDCl3), δ: 0.97 (t, 3 H, CH3, J = 7.3 Hz); 1.45 (m,
2 H, CH2); 1.67 (m, 2 H, CH2); 3.48 (m, 2 H, CH2); 7.50 (m,
3 H, Ph); 7.74 (m, 2 H, Ph); 8.10 (s, 1 H, NH); 8.42 (s, 1 H,
NH). 13C NMR (CDCl3), δ: 13.7 (CH3); 20.1 (CH2); 31.3
(CH2); 42.3 (CH2); 116.4 (CN); 126.8 (2 CH, Ph); 128.8
(2 CH, Ph); 130.6 (CH, Ph); 137.3; 155.0, 155.2, 163.3 and
This study was financially supported by the Russian
Foundation for Basic Research (Project No. 08ꢀ03ꢀ00003a).

4ꢀSubstituted 5Hꢀ1,2,3ꢀdithiazolꢀ5ꢀylidenes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 2, February, 2009
441
5. H. S. Lee, K. Kim, Tetrahedron Lett., 1998, 39, 6895.
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Received September 16, 2008;
in revised form December 25, 2008