Novel route to 2,6-diphenyl-1,4-dithiine

Full text of DOI:10.1023/B:COHC.0000048298.81086.c9

Chemistry of Heterocyclic Compounds, Vol. 40, No. 9, 2004
LETTERS TO THE EDITOR
NOVEL ROUTE TO 2,6-DIPHENYL-1,4-DITHIINE
L. G. Shagun, L. P. Ermolyuk, I. A. Dorofeev, L. N. Il'icheva, and M. G. Voronkov
Keywords: diphenacyl sulfide, 2,6-diphenyl-1,4-dithiine, sodium sulfide, thiophenacyl (2-mercapto-2-
phenylvinyl) sulfide, 1-phenyl-2-chloroethane-1,1-dithiol.
1
,4-Dithiine and its derivatives have not been well studied [1]. We synthesized 2,6-diphenyl-1,4-dithiine
for the first time [2] by hydrothiolysis of diphenacyl sulfide at -20°C. The reaction occurs through a step of
formation of thiophenacyl (2-mercapto-2-phenylvinyl) sulfide [3].
Continuing a study of the chemical properties of α-halo-gem-dithiols [4], we observed that the reaction
of an ether solution of 1-phenyl-2-chloroethane-1,1-dithiol (1) with an aqueous solution of sodium sulfide at
-
5°C leads to formation of thiophenacyl (2-mercapto-2-phenylvinyl) sulfide (2).
SH
S
2
Ph
+
+
Na2S
2 NaCl
Cl
SH
Ph
Ph
S
SH
1
2
The latter, when treated with hydrogen chloride in methanol solution at -10°C, readily eliminates
hydrogen sulfide and undergoes ring closure to form 2,6-diphenyl-1,4-dithiine (3) in 80% yield.
S
HCl
2
–
H2S
Ph
S
Ph
3
Thus we have found a novel approach to synthesis of difficultly accessible 2,6-substituted derivatives of
1
,4-dithiine, starting from highly reactive α-halo-gem-dithiols.
Thiophenacyl (2-Mercapto-2-phenylvinyl) Sulfide (2). Na S (0.4 g, 0.16 mmol) in water (3 ml) was
2
added with stirring to a solution (cooled down to -5°C) of gem-dithiol 1 (0.4 g, 2 mmol) in ether (20 ml). The
reaction mixture was stirred for 2 h until the starting dithiol 1 disappeared. The ether layer was removed and
dried above Na SO . After removal of ether, we obtained 0.25 g (85%) of sulfide 2 in the form of a thick
2
4
_
6
_________________________________________________________________________________________
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk
64033; e-mail: tim@irioch.irk.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9,
pp. 1400-1401, September, 2004. Original article submitted April 8, 2004.
1
216 0009-3122/04/4009-1216©2004 Springer Science+Business Media, Inc.

1
3
3
yellow-orange oil, identical to the product described previously in [3]. C NMR spectrum (400 MHz, CDCl ,
-
1
HMDS), δ, ppm: 45.3 (CH ); 128-135 (C ); 147 (C-SH); 194 (C=S). IR spectrum (thin film), ν, cm : 2550
2
Ph
(
SH). Found, %: C 63.10; H 4.80; S 31.28. C H S . Calculated, %: C 63.56; H 4.63; S 31.78.
16 14 3
2
,6-Diphenyl-1,4-dithiine (3). Dry HCl was passed into solution of sulfide 2 (0.25 g) in anhydrous
methanol (20 ml) for 2 h at -10°C. The reaction mixture was poured over finely crushed ice. The precipitate
formed was filtered off, washed with water, and dried under vacuum. We obtained 0.19 g (86%) of dithiine 3 as
yellow crystals; mp 78-79°C. The physicochemical characteristics of dithiine 3 were identical to those obtained
in [2].
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(
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