Disulfidation of Alkynes and Alkenes with Gallium Trichloride

Article abstract of DOI:10.1021/ol036391e

(Matrix presented) Treatment of diphenyl disulfide and terminal alkynes with gallium trichloride afforded (E)-1,2-diphenylthio-1-alkenes selectively (E/Z > 20/1). Alkenes also underwent this reaction to form trans adducts.

Full text of DOI:10.1021/ol036391e

ORGANIC
LETTERS
2004
Vol. 6, No. 4
601-603
Disulfidation of Alkynes and Alkenes
with Gallium Trichloride
Shin-ichi Usugi, Hideki Yorimitsu, Hiroshi Shinokubo, and Koichiro Oshima*
Department of Material Chemistry, Graduate School of Engineering,
Kyoto UniVersity, Kyoto 615-8510, Japan
oshima@fm1.kuic.kyoto-u.ac.jp
Received December 8, 2003
ABSTRACT
Treatment of diphenyl disulfide and terminal alkynes with gallium trichloride afforded (E)-1,2-diphenylthio-1-alkenes selectively (E/Z > 20/1).
Alkenes also underwent this reaction to form trans adducts.
Vinyl sulfides have synthetic utility in organic chemistry,1
and stereoselective sulfidation of alkynes to obtain vinyl
sulfides has been developed.2 Stereoselective disulfidation
of terminal alkynes was first reported by Sonoda et al.,
forming (Z)-1,2-dithio-1-alkenes under transition metal ca-
talysis in 1991 (Scheme 1).3 Since then, much attention has
been paid to transition-metal-catalyzed disulfidation.4 Al-
though the radical process yielded trans adducts mainly, a
mixture of E/Z isomers (E/Z < 90/10) was obtained except
Scheme 1
for some substrates.5 Highly stereoselective synthesis of (E)-
1,2-dithio-1-alkenes is needed, complementary to transition-
metal-catalyzed disulfidation of alkynes. Here we wish to
report the highly selective disulfidation of terminal alkynes
with disulfide in the presence of gallium trichloride to give
(E)-1,2-dithio-1-alkenes (E/Z > 20/1).
(1) For example: (a) Ager, D. J. Chem. Soc. ReV. 1982, 11, 493. (b)
Takeda, T.; Furukawa, H.; Fujimori, M.; Suzuki, K.; Fujiwara, T. Bull.
Chem. Soc. Jpn. 1984, 57, 1863. (c) Grobel, B.-T. Seebach, D. Synthesis
1977, 357. (d) Trost, B. M.; Lavoie, A. C. J. Am. Chem. Soc. 1983, 105,
5075. (e) Magnus, P.; Quagliato, D. J. Org. Chem. 1985, 50, 1621. (f) De
Lucchi, O.; Pasquato, L. Tetrahedron 1988, 44, 6755. (g) Pettit, G. R.; van
Tamelen, E. E. Org. React. 1962, 12, 356. (h) Boar, R. B.; Hawkins, D.
W.; McGhie, J. F.; Barton, D. H. R. J. Chem. Soc., Perkin Trans. 1 1973,
654. (i) Trost, B. M.; Ornstein, P. L. Tetrahedron Lett. 1981, 22, 3463. (j)
Wenkert, E.; Ferreira, T. W. J. Chem. Soc., Chem. Commun. 1982, 840.
(k) Hojo, M.; Tanimoto, S. J. Chem. Soc., Chem. Commun. 1990, 1284. (l)
Hojo, M.; Harada, H.; Yoshizawa, J.; Hosomi, A. J. Org. Chem. 1993, 58,
6541.
(2) (a) Dabdoub, M. J.; Guerrero, P. G., Jr. Tetrahedron Lett. 2001, 42,
7167. (b) Watanabe, S.; Mori, E.; Nagai, H.; Iwama, T.; Kataoka, T. J.
Org. Chem. 2000, 65, 8893. (c) Huang, X.; Xu, X.-H.; Zheng, W.-X. Synth.
Commun. 1999, 2399. (d) Ogawa, A.; Ikeda, T.; Kimura, K.; Hirao, T. J.
Am. Chem. Soc. 1999, 121, 5108 and references therein.
(3) (a) Kuniyasu, H.; Ogawa, A.; Miyazaki, S.; Ryu, I.; Kambe, N.;
Sonoda, N. J. Am. Chem. Soc. 1991, 113, 9796. Also see the followings
for metal-catalyzed S-S bond cleavage. (b) Kuniyasu, H. In Catalytic
Heterofunctionalization; Togni, A., Grutzmacher, H., Eds.; Wiley-VCH:
Weinhelm, 2001; p 271. (c) Kondo, T.; Mitsudo, T. Chem. ReV. 2000, 100,
3205. (d) Beleskaya, I.; Moberg, C. Chem. ReV. 1999, 99, 3435.
(4) (a) Arisawa, M.; Yamaguchi, M. Org. Lett. 2001, 3, 763. (b) Ogawa,
A.; Kuniyasu, H.; Sonoda, N.; Hirao, T. J. Org. Chem. 1997, 62, 8361. (c)
Gareau, Y.; Orellana, A. Synlett 1997, 62, 8361. (d) Gareau, Y.; Tremblay,
M.; Gauvreau, D.; Juteau, H. Tetrahedron 2001, 57, 5739.
Gallium trichloride (0.50 mmol, 1.0 M hexane solution,
0.50 mL) was added to a benzene solution (2 mL) of diphenyl
disulfide (2a, 0.50 mmol, 109 mg) and 1-octyne (1a, 0.75
mmol, 83 mg) at 0 °C under argon. The solution turned
brown. After the mixture was stirred for 20 min, extractive
workup followed by silica gel column purification afforded
(E)-1,2-di(phenylthio)-1-octene (3a, E/Z > 20/1) in 83%
1
yield (Scheme 2).6 This compound was assigned by the H
(5) (a) Heiba, E. I.; Dessau, R. M. J. Org. Chem. 1967, 32, 3837. (b)
Benati, L.; Montevacchi, P. C., Spagnolo, P. J. Chem. Soc., Perkin Trans.
1 1991, 2103. (c) Benati, L.; Montevacchi, P. C., Spagnolo, P. J. Chem.
Soc., Perkin Trans. 1 1992, 1659.
(6) Other Lewis acids such as BF3‚Et2O, TiCl4, InCl3, Ga(OTf)3, and
GaF3 were ineffective for this disulfidation. The use of GaI3 yielded 3a in
40% yield.
10.1021/ol036391e CCC: $27.50 © 2004 American Chemical Society
Published on Web 01/27/2004

Scheme 2
Scheme 3
NMR spectrum previously reported.7 Dichloromethane, 1,2-
dichloroethane, and toluene were effective solvents for this
reaction. The reaction resulted in complete recovery of the
starting material in coordinating solvents such as tetra-
hydrofuran, diethyl ether, and DMF. An excess of 1-octyne
did not influence the yield of 3a. We obtained 3a in 83%
yield with the use of 3.0 equiv of 1-octyne.
of an excess of 1-octyne (3.0 equiv) improved the yield of
1,2-di(alkylthio)-1-octene (entries 10 and 12). The reaction
of di(tert-butyl) disulfide afforded a complex mixture and
di(tert-butylthio)alkene was not detected at all.
Table 2 summarizes the results of the addition of diphenyl
disulfide to various alkenes in the presence of gallium
Various alkynes were examined under the optimized
reaction conditions (Table 1). Phenylacetylene gave (E)-1,2-
Table 2. Disulfidation of Various Alkenes with Gallium
Trichloridea
Table 1. GaCl3-Mediated Reaction of Various Alkynes with
Disulfidea
entry
R
1
R′
Ph
Ph
Ph
Ph
Ph
Ph
Ph
2
3
yield (%)
1
2
3
4
5
6
7
8
n-Bu
i-Pr
t-Bu
Ph
1b
1c
1d
1e
1f
1g
1a
1a
1a
1a
1a
1a
1e
1e
2a
2a
2a
2a
2a
2a
2a
2b
2c
2c
2d
2d
2b
2c
3b
3c
3d
3e
3f
3g
3a
3i
3j
3j
3k
3k
3l
83
58
50
87
69
40
83
85
49
63
20
49
84
50
p-CF3C6H4
p-MeOC6H4
n-C6H13
p-Tol
n-Bu
9
10c
11
12c
13
14c
s-Bu
Ph
p-Tol
n-Bu
a Reaction conditions: PhSSPh (0.50 mmol), alkene (1.0 mmol), GaCl3
3m
(0.50 mmol), PhH (2 mL), 0 °C, 40 min.
a Disulfide (0.50 mmol), alkyne (0.75 mmol), GaCl3(0.50 mmol), and
PhH (2 mL) were employed. b A reaction mixture was allowed to warm to
room temperature and stirred for 12 h. c 3.0 equiv of alkyne was used.
trichloride.8 Treatment of cyclopentene with diphenyl di-
sulfide and gallium trichloride afforded trans-1,2-di(phen-
ylthio)cyclopentane 6a in good yield. Exclusive formation
of the trans isomer was deduced by the examination of the
1H NMR spectrum previously reported.9 (E)-3-Hexene gave
meso-form 6b and (Z)-3-hexene gave dl-form 6c, which
indicates the stereospecificity of the reaction. Mono- and
disubstituted alkenes 5d-5f were suitable to yield the
corresponding adducts 6d-6f. An attempt to react diphenyl
disulfide with tri- and tetrasubstituted alkenes failed to give
the di(phenylthio)alkanes.
diphenylthio-1-phenylethene in 87% yield. The reactions of
3-methyl-1-butyne and 3,3-dimethyl-1-butyne with diphenyl
disulfide afforded the corresponding di(phenylthio)alkenes
in moderate yields. Coordinating functional groups such as
hydroxy and carbonyl groups prevented the formation of the
adduct. An internal alkyne, 4-octyne, gave (E)-4,5-di-
(phenylthio)-4-octene (3h) in low yield (14%), accompanied
with an unexpected product, (E)-4-chloro-5-phenylthio-4-
octene (4, 42%) (Scheme 3).
The addition of several disulfides to alkynes was also
examined. Treatment of di(4-methylphenyl) disulfide with
1-octyne proceeded in good yield (entry 8). However, di(n-
butyl) disulfide and di(s-butyl) disulfide gave rise to lower
yields compared to diaryl disulfides (entries 9 and 11). Use
Treatment of a 1:1 mixture of diphenyl disulfide and di-
(4-methylphenyl) disulfide with 1-octyne in the presence of
(8) BF3-catalyzed trans addition of disulfides to alkenes was reported.
However, disulfidation of alkynes gave a mixture of E/Z isomers in low
yield. See: Caserio, M. C.; Fisher, C. L.; Kim, J. K. J. Org. Chem. 1985,
50, 4390.
(9) Kitamura, T.; Matsuyuki, J.; Taniguchi, H. J. Chem. Soc., Perkin
Trans. 1 1991, 1607.
(7) Miyake, H.; Yamamura, K. Bull. Chem. Soc. Jpn. 1988, 61, 3752.
602
Org. Lett., Vol. 6, No. 4, 2004

gallium trichloride gave a statistical mixture of four adducts
(1:1:1:1) (Scheme 4). Moreover, an addition of gallium
Scheme 5
Scheme 4
In conclusion, we have developed highly stereoselective
trans addition of disulfides to alkynes selectively. This
method will be a useful synthetic tool for the formation of
(E)-dithioalkenes, complementary to transition-metal-cata-
lyzed cis addition of disulfides.
trichloride to a 1:1 mixture of diphenyl disulfide and di(4-
methylphenyl) disulfide in the absence of alkyne provided
an equilibrium mixture of disulfides (4-methylphenyl phenyl
disulfide, diphenyl disulfide, and di(4-methylphenyl) disul-
fide) in the ratio of 2:1:1 within 30 min at 0 °C.10 This
exchange reaction also proceeded with a catalytic amount
of gallium trichloride (5 mol%).
Acknowledgment. This work was supported by Grants-
in-Aids for Scientific Research (nos. 12305058 and 10208208)
from the Ministry of Education, Culture, Sports, Science and
Technology, Government of Japan.
We assume the reaction mechanism as shown in Scheme
5.7 Gallium trichloride coordinates with disulfide to form
thiosulfonium-like species 7. This species 7 reacts with
alkyne to generate a thiirenium ion 8.11 Nucleophilic attack
of 8 yields trans adduct.
Supporting Information Available: Experimental pro-
cedures and compound data. This material is available free
of charge via the Internet at http://pubs.acs.org.
OL036391E
(10) (a) Arisawa, M.; Yamaguchi, M. J. Am. Chem. Soc. 2003, 125, 6624.
Disulfide-thiol exchange reaction was reported. See: (b) Dalman, G.;
McDermed, J.; Gorin, G. J. Org. Chem. 1964, 29, 1480. (c) Eldjarn, L.;
Pihl, A. J. Am. Chem. Soc. 1957, 79, 4589.
(11) The reaction of thiirenium ion with diphenyl disulfide to afford (E)-
1,2-diphenylthio-alkene selectively in low yield was reported. See: (a)
Benati, L.; Montevecchi, P. C. Gazz. Chim. Ital. 1991, 121, 387. (b) Benati,
L.; Montevecchi, P. C. Gazz. Chim. Ital. 1989, 119, 609.
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