ORGANIC
LETTERS
2008
Vol. 10, No. 1
133-136
Indium(III) Acetate-Catalyzed
Intermolecular Radical Addition of
Organic Iodides to Electron-Deficient
Alkenes
Katsukiyo Miura,* Mitsuru Tomita, Junji Ichikawa, and Akira Hosomi*
Department of Chemistry, Graduate School of Pure and Applied Sciences, UniVersity
of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
miura@chem.tsukuba.ac.jp; hosomi@chem.tsukuba.ac.jp
Received November 8, 2007
ABSTRACT
In the presence of phenylsilane and a catalytic amount of indium(III) acetate, organic iodides added to electron-deficient alkenes in ethanol
at room temperature. Both simple and functionalized organic iodides were applicable to this reaction. A plausible reaction mechanism involves
the formation of indium hydride species by hydride transfer from silicon to indium and an indium hydride-mediated radical chain process.
Synthetic radical reactions directed toward fine organic
synthesis have rapidly been developed in the last three
decades.1 At present carbon radicals are recognized as
reactive, but controllable carbon species valuable for highly
selective, efficient bond formation. Triorganotin hydrides
such as Bu3SnH have frequently been used as efficient radical
mediators, which serve for generation of carbon radicals and
radical quenching by hydrogen-donation.1 Unfortunately,
their use has two critical drawbacks, that is, the toxicity of
organostannanes and the difficulty of product purification.2,3
A number of hydride-based radical mediators have been
developed as substitutes for triorganotin hydrides.4-7 Ad-
ditionally, the catalytic use of radical mediators in the
presence of stoichiometric hydride sources has received much
attention from the viewpoint of environmentally friendly and
economical synthesis.5c,6,8 Such catalytic reactions are very
effective in radical reduction and intramolecular radical
addition of organic halides and pseudohalides. However,
intermolecular addition of these radical precursors (R-X)
to alkenes (CH2dCHE) using catalytic mediators (M-H)
shows much room for improvement (Scheme 1).6b,8b
(4) Hydrosilanes and related compounds: (a) Giese, B.; Kopping, B.;
Chatgilialoglu, C. Tetrahedron Lett. 1989, 30, 681. (b) Chatgilialoglu, C.
Acc. Chem. Res. 1992, 25, 188. (c) Chatgilialoglu, C.; Guerra, M.; Guerrini,
A.; Seconi, G. J. Org. Chem. 1992, 57, 2427. (d) Yamazaki, O.; Togo, H.;
Matsubayashi, S.; Yokoyama, M. Tetrahedron 1999, 55, 3735. (e) Studer,
A.; Amrein, S.; Schleth, F.; Schulte, T.; Walton, J. C. J. Am. Chem. Soc.
2003, 125, 5726.
(5) Hydrogermanes: (a) Sakurai, H.; Mochida, K.; Hosomi, A.; Mita,
F. J. Organomet. Chem. 1972, 38, 275. (b) Chatgilialoglu, C.; Ballestri, M.
Organometallics 1995, 14, 5017. (c) Nakamura, T.; Yorimitsu, H.;
Shinokubo, H.; Oshima, K. Bull. Chem. Soc. Jpn. 2001, 74, 747. (d) Miura,
K.; Ootsuka, K.; Hosomi, A. Synlett 2005, 3151.
(6) Indium and gallium hydrides: (a) Inoue, K.; Sawada, A.; Shibata,
I.; Baba, A. J. Am. Chem. Soc. 2002, 124, 906. (b) Hayashi, N.; Shibata, I.;
Baba, A. Org. Lett. 2005, 7, 3093. (c) Takami, K.; Mikami, S.; Yorimitsu,
H.; Shinokubo, H.; Oshima, K. Tetrahedron 2003, 59, 6627 and references
cited therein.
(7) Dialkyl phosphites and hypophosphorous acid: Barton, D. H. R.;
Jang, D. O.; Jaszberenyi, J. C. J. Org. Chem. 1993, 58, 6838 and references
cited therein.
(1) (a) Renaud, P.; Sibi, M. P. Radicals in Organic Synthesis; Wiley-
VCH: Weinheim, Germany, 2001. (b) Curran, D. P.; Porter, N. A.; Giese,
B. Stereochemistry of Radical Reactions; VCH: Weinheim, Germany, 1996.
(c) Curran, D. P. In ComprehensiVe Organic Synthesis; Trost B. M.,
Fleming, I., Eds.; Pergamon Press: Oxford, UK, 1991; Vol. 4, Chapter
4.1-4.2, p 715. (d) Giese, B. Radicals in Organic Synthesis: Formation of
Carbon-Carbon Bonds; Pergamon Press: Oxford, UK, 1986.
(2) Boyer, I. J. Toxicology 1989, 55, 253.
(8) (a) Corey, E. J.; Suggs, J. W. J. Org. Chem. 1975, 40, 2554. (b)
Giese, B.; Gonza´lez-Go´mez, J. A.; Witzel, T. Angew. Chem., Int. Ed. Engl.
1984, 23, 69. (c) Lopez, R. M.; Hays, D. S.; Fu, G. C. J. Am. Chem. Soc.
1997, 119, 6949.
(3) Baguley P. A.; Walton, J. C. Angew. Chem., Int. Ed. 1998, 37, 3073
and references cited therein.
10.1021/ol702712d CCC: $40.75
© 2008 American Chemical Society
Published on Web 12/12/2007