1,7-Dithioxo systems. Reaction of bis(5,5-dimethyl-3-thioxo-cyclohex-1-en- 1-yl) sulfide with amines

Article abstract of DOI:10.1134/S1070428008040118

Reactions of amines (N,N-dimethylethane-1,2-diamine, benzylamine, aniline) with bis(5,5-dimethyl-3-thioxocyclohex-1-en-1-yl) sulfide result in cleavage of the sulfide bond and formation of the corresponding 3-amino-5,5- dimethylcyclohex-2-ene-1-thiones. A

Full text of DOI:10.1134/S1070428008040118

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 4, pp. 532–535. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © L.V. Timokhina, O.V. Sokol’nikova, L.V. Kanitskaya, M.P. Yashchenko, M.G. Voronkov, 2008, published in Zhurnal Organicheskoi
Khimii, 2008, Vol. 44, No. 4, pp. 537–540.
1,7-Dithioxo Systems. Reaction of Bis(5,5-dimethyl-3-thioxo-
cyclohex-1-en-1-yl) Sulfide with Amines
L. V. Timokhina, O. V. Sokol’nikova, L. V. Kanitskaya,
M. P. Yashchenko, and M. G. Voronkov
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: tim@irioch.irk.ru
Received June 11, 2007
Abstract—Reactions of amines (N,N-dimethylethane-1,2-diamine, benzylamine, aniline) with bis(5,5-di-
methyl-3-thioxocyclohex-1-en-1-yl) sulfide result in cleavage of the sulfide bond and formation of the corre-
sponding 3-amino-5,5-dimethylcyclohex-2-ene-1-thiones. Aminolysis of bis(5,5-dimethyl-3-oxocyclohex-1-en-
1-yl) sulfide occurs at the carbonyl groups with conservation of the divinyl sulfide fragment.
DOI: 10.1134/S1070428008040118
Studies on bis(chalcogenoxopropenyl) sulfide sys-
tems like (Se)S=CC=CSC=CC=S(Se) as possible solar
energy transducers [1] requires knowledge of their
chemical properties. Using bis(5,5-dimethyl-3-thioxo-
cyclohex-1-en-1-yl) sulfide (I) as an example, we ex-
amined reactions of α,β-unsaturated 1,7-dithioxo sul-
fides with amines. As a rule, thioketones readily react
with amines to give Schiff bases [2]. We expected that
aminolysis of dithioxo sulfide I will involve one or
both thiocarbonyl groups to produce the corresponding
mono- and diimino sulfides. Compounds having nitro-
gen-containing functional groups conjugated with
a sulfide moiety could exhibit some biological activity.
Obviously, enamino thiones IIa–IIc were formed as
a result of cleavage of the sulfide bond in initial
compound I.
Compounds IIa–IIc were synthesized by us pre-
viously by several methods, including sulfurization of
3-aminocyclohex-2-en-1-ones with diphosphorus deca-
sulfide, hydrothiolysis of 3-iminocyclohex-1-en-1-
amines, and aminolysis of 3-alkoxycyclohex-2-ene-1-
thiones [3, 4]. In the present communication we pre-
sent the 13C NMR spectra of thioketones IIb and IIc.
An oxygen-containing analog of dithioxo sulfide I,
bis(5,5-dimethyl-3-oxocyclohex-1-en-1-yl) sulfide
(III), reacted with amines under more severe condi-
tions (on heating for a longer time), but its conversion
did not exceed 30%. Unlike compound I, in the reac-
tions of diketone III with amines the divinyl sulfide
fragment in molecule III remained intact. The reaction
of III with benzylamine gave previously unknown
3-(3-benzylimino-5,5-dimethylcyclohex-1-en-1-yl-
sulfanyl)-5,5-dimethylcyclohex-2-en-1-one (IV)
(Scheme 2). The 13C NMR spectrum of the isolated
product mixture (see table) contained signals belong-
ing to unreacted sulfide III and signals with different
intensities at δC 165.1/167.5 and 160.1/162.2 ppm,
which were assigned, respectively, to the C3 (C=N) and
C1 atoms (S–C=C), the intensity ratio being ~1:2 in
each couple. The C2 and C2′ nuclei gave rise to four
signals in the δC range from 118 to 124 ppm with
the same intensity ratio. The =NCH2 carbon nucleus
However, contrary to the expectations, the products
of reactions of sulfide I with N,N-dimethylethane-
1,2-diamine, benzylamine, and aniline in benzene or
chloroform at 20°C were mainly 3-[2-(dimethylamino)-
ethylamino]-5,5-dimethylcyclohex-2-ene-1-thione
(IIa), 3-benzylamino-5,5-dimethylcyclohex-2-ene-1-
thione (IIb), and 5,5-dimethyl-3-phenylaminocyclo-
hex-2-ene-1-thione (IIc), respectively (Scheme 1).
Scheme 1.
Me
Me
Me
Me
Me
Me
RNH2
S
S
S
S
NHR
I
IIa–IIc
R = Me2NCH2CH2 (a), PhCH2 (b), Ph (c).
532

1,7-DITHIOXO SYSTEMS.
533
Scheme 2.
three singlets at δ 0.98, 1.00, and 1.11 ppm. According
to the signal intensity, the ratio of compounds III, V,
and VI is ~100:10:6.
7
Me
7
Me
7'
Me
7'
Me
Me
Me
Me
Me
5
2
5'
2'
RNH2
4
3
6
1
6'
1'
4'
3'
It should be noted that structural analogs of com-
pound III, bis(2-aryl-3-oxoinden-1-yl) sulfides, react
with amines to give mixtures of the corresponding
enamino ketones and enamino imines [6].
O
S
O
RN
S
O
III
IV, V
Me
Me
Me
Me
EXPERIMENTAL
+
PhN
S
NPh
The IR spectra were recorded in KBr on a Bruker
VI
1
IFS 25 instrument. The H and 13C NMR spectra were
IV, V, R = PhCH2.
measured on a Bruker DPX-400 spectrometer at 400.1
and 100.4 MHz, respectively, using HMDS as external
reference. Quantitative 13C NMR analysis was per-
formed using a pulse delay of 2.5 s and a pulse width
of 90°; tris(acetylacetonato)chromium was added as
relaxant to a concentration of 0.02 M. The relative
error in the determination of fractions of components
was 7.8%. The progress of reactions and the purity of
products were monitored by TLC on Silufol UV-254
plates using chloroform–ethyl acetate (3:1) as eluent.
resonated at δC 53.2 and 55.0 ppm, and the signal at
δC 195.3 ppm corresponded to the carbonyl carbon
atom. In the aromatic region of the spectrum we
observed two groups of partially overlapped signals at
δC 125–128 and 135–140 ppm. This spectral pattern
led us to presume formation of compound IV as a mix-
ture of two stereoisomers.
Quantitative analysis of the 13C NMR spectrum [5]
showed that the fractions of carbon atoms belonging to
dioxo sulfide III and compound IV are 0.728 and
0.272, respectively, i.e., the molar ratio of compounds
III and IV in the isolated mixture is 100 :8.8. The
elemental composition of the mixture, calculated from
the 13C NMR spectrum was consistent with that deter-
mined by elemental analysis (see Experimental), which
provides an additional proof for the assumed structure
of compound IV.
3,3′-Thiobis(5,5-dimethylcyclohex-2-ene-1-thione)
(I) was synthesized according to the procedure re-
ported in [7]. 3,3′-Thiobis(5,5-dimethylcyclohex-2-en-
1-one) (III) was prepared as described in [8].
3-[2-(Dimethylamino)ethylamino]-5,5-dimethyl-
cyclohex-2-ene-1-thione (IIa). A solution of 0.31 g
(1 mmol) of sulfide I in 10 ml of freshly distilled
13C NMR spectra (δC, ppm) of compounds III–VI
By reaction of dioxo sulfide III with aniline we ob-
tained previously unknown 3-(5,5-dimethyl-3-phenyl-
iminocyclohex-1-en-1-ylsulfanyl)-5,5-dimethylcyclo-
hex-2-en-1-one (V) and N,N′-[3,3′-thiobis(5,5-dimeth-
ylcyclohex-2-en-3-ylidene)]dibenzenamine (VI)
Atom
III
155.11 160.1, 162.2
129.00 118–124
IV
V
VI
C1
C2
C3
C4
C5
C6
C1′
C2′
C3′
C4′
C5′
C6′
C7
C7′
141.15
115.08
165.81
040.96
0a34.02a
0a47.53a
160.02
120.41
196.12
050.89
0a32.96a
0a44.32a
149.90
118.46
166.50
042.74
033.12
045.12
149.90
118.46
166.50
045.43
032.27
042.80
196.21 165.1, 167.5
050.69 50.3, 51.0
1
(Scheme 2). In the H and 13C NMR spectra of the
isolated product we observed signals from unreacted
compound III and those with lower intensity, which
were assigned to compounds V and VI (see Experi-
mental and table). The aromatic region of the 1H NMR
spectrum contained three groups of signals, indicating
the presence of monosubstituted phenyl rings: over-
lapping doublets at δ 6.65–6.74 ppm were assigned to
the ortho-protons, and two couples of partially over-
lapping triplets at δ 7.03–7.17 and 7.23–7.33 ppm cor-
responded to protons in the meta and para positions.
Olefinic proton singlets at δ 5.90 and 6.40 ppm are
likely to belong to 2-H (2′-H) in unsymmetrical sulfide
V, and the signal at δ 6.00 ppm, to analogous protons
in diimino derivative VI. Methyl protons resonated as
034.01
044.56
155.11
129.00
196.21
050.69
034.01
044.56
32–34
118–124
195.3
32–34
027.77 28.0–29.2 27.97–27.80 27.97–27.80
027.77 28.0–29.2 27.97–27.80 27.97–27.80
a
Alternative assignment is possible.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 4 2008

TIMOKHINA et al.
534
chloroform was cooled to 2–5°C, and a solution of
0.18 g (2 mmol) of N,N-dimethylethane-1,2-diamine in
3 ml of chloroform was added dropwise under stirring
in an argon atmosphere. The mixture was stirred for
2 h at 2–5°C, vigorous evolution of hydrogen sulfide
[identified by a test with a solution of Pb(OAc)2] was
observed, and the original dark green color changed to
dark orange. The mixture was then washed with water,
the organic phase was dried over Na2SO4, the solvent
was removed, and the tarry residue was recrystallized
from ethanol–hexane (1:1). Yield 0.15 g (68%), orange
finely crystalline powder, mp 88–91°C; published data
[4]: mp 90–92°C. IR spectrum, ν, cm–1: 1049 (C=S),
1543 (C=C), 3238 (NH). Found, %: C 62.86; H 9.54;
N 12.34; S 14.09. C12H22N2S. Calculated, %: C 63.72;
H 9.73; N 12.39; S 14.45.
Reaction of dioxo sulfide III with benzylamine.
A solution of 0.39 g (3.6 mmol) of benzylamine in
5 ml of benzene was added dropwise to a solution of
0.5 g (1.8 mmol) of sulfide III in 10 ml of benzene.
The mixture was stirred for 22 h at 70–75°C, and it
changed from colorless to red–orange. The mixture
was then washed with water saturated with carbon
dioxide, the organic phase was dried over Na2SO4, and
the solvent was removed under reduced pressure. The
residue, 0.48 g, was a mixture of initial sulfide III and
3-(3-benzylimino-5,5-dimethylcyclohex-1-en-1-ylsul-
fanyl)-5,5-dimethylcyclohex-2-en-1-one (IV). IR spec-
trum, ν, cm–1: 698, 735 (δC–Harom), 1556 br (C=C,
C=CS, C=N), 1654 (C=O). Found, %: C 70.36; H 7.40;
N 2.67; S 10.74. Calculated (from the 13C NMR spec-
trum), %: C 69.7; H 7.9; N 4.0; S 11.2.
3-Benzylamino-5,5-dimethylcyclohex-2-ene-1-
thione (IIb). A solution of 0.21 g (2 mmol) of benzyl-
amine in 5 ml of benzene was added dropwise to
a dark green solution of 0.31 g (1 mmol) of sulfide I in
10 ml of anhydrous benzene. The mixture was stirred
for 4 h at 20°C in a continuous stream of argon, evolu-
tion of hydrogen sulfide was observed, and the mixture
turned dark orange. The precipitate was filtered off,
washed with benzene, and dissolved in chloroform–
ethyl acetate (3:1), the solution was passed through
a column charged with silica gel (100/400 mesh), and
the column was eluted with chloroform–ethyl acetate
(3:1). Yield 0.16 g (64%), bright yellow needles,
mp 136–137°C. The melting point and IR spectrum of
the product were consistent with those reported in [3].
13C NMR spectrum (CDCl3), δC, ppm: 27.6 (CH3),
33.5 (C5), 43.4 (C4), 47.1 (CH2NH), 57.4 (C6), 111.9
(C2), 160.5 (C3), 219.2 (C=S), 127.4 (Cp), 128.0 (Cm),
128.9 (Co), 135.9 (Ci). Found, %: C 73.95; H 7.81;
N 5.57; S 13.02. C15H19NS. Calculated, %: C 73.47;
H 7.76; N 5.71; S 13.06.
Reaction of dioxo sulfide III with aniline. The
reaction mixture obtained from 0.5 g (1.8 mmol) of
sulfide III and 0.34 g (3.6 mmol) of aniline in 10 ml of
benzene was stirred for 7 days at 20°C. The bright
yellow mixture was washed with water saturated with
carbon dioxide, the organic phase was dried over
Na2SO4, the solvent was removed under reduced pres-
sure, and the tarry residue was treated with hexane.
From the hexane solution we isolated 0.36 g (73%) of
unreacted sulfide III. The undissolved material was
ground with a small amount of diethyl ether to obtain
0.1 g of a mixture of compound III, 3-(5,5-dimethyl-3-
phenyliminocyclohex-1-en-1-ylsulfanyl)-5,5-dimethyl-
cyclohex-2-en-1-one (V), and N,N′-[3,3′-thiobis(5,5-
dimethylcyclohex-2-en-3-ylidene)]dibenzenamine (VI)
as a light orange powder. IR spectrum, ν, cm–1: 696,
756 (δC–Harom); 1497, 1526 (C=C, C=Carom); 1582
(C=CS); 1603 (C=N); 1657 (C=O). 1H NMR spectrum
(CDCl3), δC, ppm: 0.98 s, 1.00 s, 1.11 s (CH3); 5.90 s,
6.00 s, 6.40 s (HC=); 6.65–6.74 d (o-H); 7.03–7.17 t
(m-H); 7.23–7.33 (p-H). 13C NMR spectrum (CDCl3),
δC, ppm: 119.38 (Co), 123.69 (Cm), 126.41 (Cp), 137.87
(Ci) (V); 123.07 (Cp), 123.80 (Co), 126.41 (Cm), 139.44
(Ci) (VI).
5,5-Dimethyl-3-phenylaminocyclohex-2-ene-1-
thione (IIc). The reaction was carried out as described
above using 0.31 g (1 mmol) of sulfide I in 10 ml of
anhydrous benzene and 0.19 g (2 mmol) of aniline in
5 ml of anhydrous benzene. Yield 0.15 g (65%),
orange crystals, mp 180–182°C. The melting point and
IR spectrum of the product were consistent with those
reported in [3]. 13C NMR spectrum (CDCl3), δC, ppm:
28.0, 29.7 (CH3), 33.6 (C5), 43.3 (C4), 57.7 (C6), 114.1
(C2), 158.5 (C3), 221.9 (C=S), 124.6 (Cm), 126.8 (Cp),
129.3 (Co), 137.1 (Ci). Found, %: C 72.63; H 7.35;
N 6.15; S 14.09. C14H17NS. Calculated, %: C 72.72;
H 7.36; N 6.06; S 13.85.
This study was performed under financial support
by the Council for Grants at the President of the
Russian Federation (project no. NSh-4575.2006.3) and
by the Russian Foundation for Basic Research (project
no. 05-03-32036).
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