ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 4, pp. 586–587. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © L.V. Timokhina, L.V. Kanitskaya, 2010, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 4, pp. 593–594.
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Hydrothiolysis of N,N-Dimethyl-3-methylsulfanyl-3-phenyl-
prop-2-en-1-iminium Iodide
L. V. Timokhina and L. V. Kanitskaya
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: tim@irioch.irk.ru
Received July 19, 2009
DOI: 10.1134/S107042801004024X
We previously showed that the reaction of 3-chloro-
N,N-dimethyl-3-phenylprop-2-en-1-iminium perchlo-
rate with hydrogen sulfide in anhydrous DMF at
–60°C involved attack by the sulfur-centered nucleo-
phile exclusively at the C=N+ iminium carbon atom
with formation of 3-chloro-3-phenylprop-2-enethial
[1]. In continuation of our studies on regioselectivity
of nucleophilic substitution in conjugated iminium
cations we examined hydrothiolysis of N,N-dimethyl-
3-methylsulfanyl-3-phenylprop-2-en-1-iminium iodide
(I). It was found that the reaction of salt I, as well as of
its 3-chloro-substituted analog, with hydrogen sulfide
in DMF or methanol at room temperature involves
only the C=N+ bond with formation of 3-methylsul-
fanyl-3-phenylprop-2-enethial (II) in situ. Compound
II was not isolated from the reaction mixture due to its
fast transformation into slightly colored 2,4,6-tris(2-
methylsulfanyl-2-phenylethenyl)-1,3,5-trithiane (III).
The ability of thioaldehydes to form trimers is well
known. It was also noted that hydroxy-containing sol-
vents favor the trimerization process [2]. We per-
formed quantum-chemical analysis of possible struc-
tural transformations of thioaldehyde II and revealed
its ability to undergo trimerization in polar medium
[3]. Compound III decomposed on storage to give
3-methylsulfanyl-3-phenylprop-2-enal [4].
2,4,6-Tris(2-methylsulfanyl-2-phenylethenyl)-
1,3,5-trithiane (III). a. A solution of 0.33 g (1 mmol)
of salt I in 5 ml of anhydrous dimethylformamide was
cooled to –50°C and purged with argon, and hydrogen
sulfide was then passed through the solution. The mix-
ture changed from dark yellow to red yellow. After 1 h,
the mixture was allowed to gradually warm up to
–10°C and poured into an ice–water mixture. The pre-
cipitate was filtered off, washed with ice water, and
dried in a vacuum desiccator over phosphoric anhy-
dride. Yield 0.18 g (95%).
b. Dry hydrogen sulfide was passed over a period
of 1 h through a solution of 0.66 g (2 mmol) of salt I in
10 ml of anhydrous methanol, cooled to –20°C. The
mixture lightened, and the precipitate was filtered
off, washed with methanol, and dried under reduced
pressure. Yield 0.37 g (97%). Light yellow crystals
2 · I–
Ph
1
NMe
S
Ph
decomposing at 76–80°C. H NMR spectrum, δ, ppm:
H2S
1.02 s (6H, CH3), 2.15 s (3H, CH3), 5.12 m (3H, 2-H,
4-H, 6-H), 5.65 m (3H, CH=), 7.30 m (15H, Ph).
Found, %: C 61.50; H 5.09; S 33.07. C30H30S6. Calcu-
lated, %: C 61.85; H 5.15; S 33.00.
–Me2NH·HI
SMe
SMe
I
II
Ph
S
Ph
After storage for a week at room temperature on
exposure to air compound III was transformed into
a dark yellow substance which was dissolved in
chloroform, and the solution was passed through
a column charged with silica gel (40–100 mesh). The
column was eluted with chloroform–ethyl acetate
SMe
S
S
SMe
Ph
SMe
III
586
Timokhina
