ORGANIC
LETTERS
2
001
Vol. 3, No. 8
245-1248
Benzylic Intermolecular Carbon−Carbon
Bond Formation by Selective Anodic
Oxidation of Dithioacetals
1
Kazuhiro Chiba,* Rikiya Uchiyama, Shokaku Kim, Yoshikazu Kitano, and
Masahiro Tada
Laboratory of Bio-organic Chemistry, Tokyo UniVersity of Agriculture and Technology,
3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
Received February 20, 2001
ABSTRACT
Novel anodic intermolecular carbon−carbon bond formation has been accomplished by the oxidative carbon−sulfur bond fission of benzylic
dithioacetals to give a wide variety of aromatic compounds. The substitution reaction successfully took place by the selective anodic oxidation
of a sulfur atom of a dithioacetal. Stepwise double-substitution reactions were also achieved by the regulation of oxidation potential.
It has recently been shown that electrosynthesis provides an
atom-substituted organotin compounds gave R-heteroatom-
substituted carbocations via carbon-tin bond cleavage. It
has been further revealed that the R-heteroatoms assist in
lowering oxidation potentials and in cleaving the carbon-
tin bonds. Organosulfur compounds have attraction that can
also secure anodic intermolecular carbon-carbon bond
formation initiated by oxidative carbon-sulfur bond fission.
Previously, we accomplished anodic generation of unstable
o-quinomethanes and o-quinodimethanes initiated by ben-
zylic carbon-sulfur bond fission, and these intermediates
were successfully trapped by alkenes to give varied poly-
efficient means of inter- and intramolecular carbon-carbon
1
bond formation. The potential of the electrochemical method
is used to generate reactive intermediates to construct a wide
variety of products under mild conditions. The anodic
oxidation of heteroatom compounds often leads to the
formation of the carbocation adjacent to the heteroatom, and
the cation reacts with the heteroatom or with activated carbon
nucleophiles, such as allylsilanes and sily ethers, to give the
2
final products. For example, anodic oxidation of R-hetero-
3
cyclic compounds.
(1) Moeller, K. D.; Marzabadi, M. R.; New, D. G.; Chiang, M. Y.; Keith,
S. J. Am. Chem. Soc. 1990, 112, 6123. Hudson, C. M.; Marzabadi, M. R.;
Moeller, K. D.; New, D. G.; Tinao, L. V. J. Am. Chem. Soc. 1992, 114,
Among those heteroatom compounds that act as precursors
of carbocations, dithioacetals have been utilized in chemical
reactions because of their high reactivity and ease of
preparation. Intermolecular carbon-carbon bond formation
using dithioacetal has been primarily accomplished by Lewis
acid catalyzed carbon-sulfur bond fission followed by a
1
033. Hudson, C. M.; Moeller, K. D. J. Am. Chem. Soc. 1994, 116, 3347.
Swenton, J. S.; Callinan, A.; Chen, Y.; Rohde, J. J.; Kerns, M. L.; Morrow,
G. W. J. Org. Chem. 1996, 61, 1267. Gao, J.; Rusling, J. F.; Zhou, D.
1
996, J. Org. Chem. 61, 5972. Little, D. R. Chem. ReV. 1996, 96, 93.
Yoshida, J.; Suga, S.; Suzuki, S.; Kinomura, N.; Yamamoto, A.; Fujiwara,
K. J. Am. Chem. Soc. 1999, 121, 9546. Frey, D. A.; Reddy, S. H. K.;
Moeller, K. D. J. Org. Chem. 1999, 64, 2805. Suga, S.; Suzuki, S.;
Yamamoto, A.; Yoshida, J. J. Am. Chem. Soc. 2000, 122, 10244.
(3) Chiba, K.; Sonoyama, J.; Tada, M. J. Chem. Soc., Chem. Commun.
1995, 1381. Chiba, K.; Yamaguchi, Y.; Tada, M. Tetrahedron Lett. 1998,
39, 9035. Chiba, K.; Arakawa, T.; Tada, M. J. Chem. Soc., Perkin Trans.
1 1998, 17, 2939-42. Jinno, M.; Kitano, Y.; Tada, M.; Chiba, K. Org.
Lett. 1999, 1, 435.
(
2) Yoshida, J.; Takada, K.; Ishichi, Y.; Isoe, S. J. Chem. Soc., Chem.
Commun. 1994, 2361. Yoshida, J. Synth. Org. Chem. Jpn. 1995, 53,
3.Yoshida, J.; Nishiwaki, K. J. Chem. Soc., Dalton Trans. 1998, 2589.
Yoshida, J.; Suga, S.; Fuke, K.; Watanabe, M. Chem. Lett. 1999, 3, 251.
5
1
0.1021/ol015734a CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/27/2001
Chiba
