Russian Journal of General Chemistry, Vol. 73, No. 2, 2003, pp. 321 322. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 2, 2003,
pp. 345 346.
Original Russian Text Copyright
2003 by Kirpichenko, Shainyan, Suslova, Albanov.
LETTERS
TO THE EDITOR
Lithiation of 3,3-Dimethyl-3-silathiane as a Route
to -Substituted Six-Membered Cyclic Organosilicon Sulfides
S. V. Kirpichenko, B. A. Shainyan, E. N. Suslova, and A. I. Albanov
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia
Received May 15, 2002
Thiasilacycloalkanes are most commonly prepared
by cyclization of ( , -dihaloalkyl)dialkylsilanes under
the action of S-nucleophiles, intramolecular cycliza-
tion of (chloroalkyl)(mercaptoalkyl)silanes, or intra-
molecular free-radical cyclization of (mercaptoalkyl)-
alkenylsilanes [1]. In particular, these methods have
been used for preparing, in good yields, a rare re-
presentative of six-membered heterocycles, 3,3-di-
methyl-3-silathiane [2 5]. However, because of the
inaccessibility of starting materials, the above
methods have scarcely been used in the synthesis of
2-Substituted 3,3-dimethyl-3-silathianes IIIa
IIIc. A 1.6 M solution of butyllithium in hexane
(Merck), 7 ml, was added with stirring at 0 C to a
solution of 1.46 g of 3,3-dimethyl-3-silathiane (I) and
1.42 g of tetramethylethylenediamine in 3 ml of THF.
After 1-h stirring, a solution of halide RX (11 mmol
in 2 ml of THF) was added. The reaction mixture was
stirred at room temperature for 2 8 h, poured into
water, and acidified with 10% HCl to pH 5. The or-
ganic layer was separated, and the aqueous layer was
treated with hexane. The combined organic solutions
2
2
-substituted 3-silatianes of which 2-methyl [6] and
-phenyl derivatives [3] have only been described. At
were dried with MgSO , and the solvent was removed
4
by rotary evaporation. Compounds IIIa and IIIc were
isolated by vacuum distillation. Compound IIIb was
purified by column chromatography on Silica gel 60
(35 70 mesh, Merck) with gradient elution (hexane,
hexane cyclohexane, and hexane benzene).
the same time, acyclic -silyl sulfides are not infre-
quently functionalized via reactions with electrophiles
of -carbanions generated from 2-substituted 3-sila-
thianes [1]. The latter approach was recenty applied
for -substitution of a thiane deprotonated with
n-BuLi/KOBu-t [7].
2
,3,3-Trimethyl-3-silathiane (IIIa). Physicoche-
1
mical characteristics and H NMR spectrum are si-
milar to those described in [9].
We found that -carbanion II generated from si-
lathiane I reacts with electrophiles RX to give 2-sub-
stituted 3-silatianes IIIa IIIc in yields depending on
the nature of the base and electrophile. Thus, suc-
cessive treatment of silathiane I with n-butyllithium
2
-Benzyl-3,3-dimethyl-3-silathiane (IIIb). R 0.41
f
2
3
1
(
cyclohexane benzene, 2:1), n 1.5172. H NMR
D
spectrum, , ppm: 0.00 s (3H, MeSi), 0.18 s (3H,
2
3
(
1.1 equiv) and methyl iodide in THF at 0 C gives
MeSi), 0.60 d.d.d (1H, 4-CH, J 14.7, J 10.2 and
3
4
heterocycle IIIa in 44% yield, while the deptoronation
of compound I with the n-butyllithium tetramethylene- 1.94 d.d.d.d.d (1H, 5-CH, J 13.6, J 9.6 and 2.6 Hz),
4.4 Hz), 0.78 d.d.d.d (1H, 4-CH, J 7.7, 3.9, J 0.5 Hz),
2
3
3
diamine complex (TMEDA) increases the yield of
compound IIIa to 67%. However, even under such
conditions and at longer reaction times, the yield of
compound IIIb is as low as 15%. In the latter case,
2.09 d.d. d.d.d (1H, 5-CH, J 7.3 and 2.5 Hz), 2.21
3
d.d (1H, 2-CH, J 10.1 and 6.0 Hz), 2.40 d.d.d (1H,
2
6-CH, J 14.2 Hz), 2.58 d.d.d.d (1H, 6-CH), 2.76 d.d
2
(1H, CH , J 14.2 Hz), 2.94 d.d (1H, CH ), 7.30 m
aa
1
3
1
-chloro-1,2-diphenylethane PhCHClCH Ph (IV) was
(5H, C H ). C NMR spectrum,
, ppm: 5.6
2
6
5
C
4
5
2
isolated as by-product (yield 8%). The mechanism of
(MeSi), 3.1 (MeSi), 13.7 (C ), 27.0 (C ), 30.7 (C ),
31.1 (C ), 35.8 (C ), 126.2 (C ), 128.2 (C ), 128.8
6
formation of compound IV has been proposed in [8].
o
p
2
9
(
C ), 140.8 (C ). Si NMR spectrum, Si, ppm: 5.9.
m i
R
Me Si
S n-BuLi/TMEDA Me Si
S
Me Si
S
2
2
2
Found, %: S 14.08; Si 11.16. C H SSi. Calculated,
RX
13 20
%
: S 13.56; Si 11.88.
,3-Dimethyl-2-(trimethylsilyl)-3-silathiane (IIIc).
I
II
IIIa IIIc
3
2
0
1
RX = MeI (a), C H CH Cl (b), (CH ) SiCl (c).
Yield 50%, bp 87 C (2 mm), n 1.4963. H NMR
6
5
2
3 3
D
1
070-3632/03/7302-0321$25.00 2002 MAIK Nauka/Interperiodica
Kirpichenko
