ORGANIC
LETTERS
2005
Vol. 7, No. 14
3001-3004
Gold(I)−Phosphine Catalyst for the
Highly Chemoselective Dehydrogenative
Silylation of Alcohols
Hajime Ito,* Katsuhiro Takagi, Takahiro Miyahara, and Masaya Sawamura*
DiVision of Chemistry, Graduate School of Science, Hokkaido UniVersity, and
PRESTO, JST, Sapporo 060-0810, Japan
hajito@sci.hokudai.ac.jp; sawamura@sci.hokudai.ac.jp
Received April 30, 2005
ABSTRACT
A gold(I) complex of Xantphos AuCl(xantphos) catalyzes the dehydrogenative silylation of alcohols with high chemoselectivity and solvent
tolerance. It is selective for the silylation of hydroxyl groups in the presence of alkenes, alkynes, alkyl halides (RCl, RBr), ketones, aldehydes,
conjugated enones, esters, and carbamates.
The development of environmentally benign processes is an
important subject in organic synthesis.1 We have focused
on the dehydrogenative silylation of hydroxy groups with
hydrosilanes as a useful method with high atom effciency.2-5
Recently, we reported that a Cu(I)-Xantphos catalyst is
remarkably active for the dehydrogenative silylation of
alcohols with high selectivity.6,7 These studies revealed a
strong ligand effect of Xantphos, which accelerates dehy-
drogenative silylation of alcohols.
Here, we report that a gold(I) complex of Xantphos
catalyzes the dehydrogenative silylation of alcohols and
(1) (a) Trost, B. M. Science 1991, 254, 1471-1477. (b) Trost, B. M.
Angew. Chem., Int. Edit. Engl. 1995, 34, 259-281. (c) Sheldon, R. A. Pure
Appl. Chem. 2000, 72, 1233-1246.
(4) Several transition metal catalysts are reported to have limited
compatibility with functional groups (alkenes, alkynes and ketones); see:
(a) Oehmichen, U.; Singer, H. J. Organomet. Chem. 1983, 243, 199-204.
(b) Luo, X. L.; Crabtree, R. H. J. Am. Chem. Soc. 1989, 111, 2527-2535.
(c) Doyle, M. P.; High, K. G.; Bagheri, V.; Pieters, R. J.; Lewis, P. J.;
Pearson, M. M. J. Org. Chem. 1990, 55, 6082-6086. (d) Gregg, B. T.;
Cutler, A. R. Organometallics 1994, 13, 1039-1043. (e) Lorenz, C.;
Schubert, U. Chem. Ber. 1995, 128, 1267-1269. (f) Maifeld, S. V.; Miller,
R. L.; Lee, D. Tetrahedron Lett. 2002, 43, 6363-6366. (g) Schmidt, D.
R.; O’Malley, S. J.; Leighton, J. L. J. Am. Chem. Soc. 2003, 125, 1190-
1191. (h) Miller, R. L.; Maifeld, S. V.; Lee, D. Org. Lett. 2004, 6, 2773-
2776.
(5) For Lewis acid and base catalysts, see: (a) Tanabe, Y.; Okumura,
H.; Maeda, A.; Murakami, M. Tetrahedron Lett. 1994, 35, 8413-8414.
(b) Blackwell, J. M.; Foster, K. L.; Beck, V. H.; Piers, W. E. J. Org. Chem.
1999, 64, 4887-4892. See also ref 3d.
(6) Ito, H.; Watanabe, A.; Sawamura, M. Org. Lett. 2005, 7, 1869-
1871.
(2) Greene, T. W.; Wuts, P. G. M. ProtectiVe Groups in Organic
Synthesis, 3rd ed.; Wiley & Sons: New York, 1999.
(3) For selected references for transition metal-catalyzed silylation of
alcohols with hydrosilanes, see: (a) Sommer, L. H.; Lyons, J. E. J. Am.
Chem. Soc. 1969, 91, 7061-7067. (b) Ojima, I.; Kogure, T.; Nihonyanagi,
M.; Kono, H.; Inaba, S. Chem. Lett. 1973, 501-504. (c) Chalk, A. J. J.
Chem. Soc., Chem. Commun. 1970, 847-848. (d) Lukevics, E.; Dzintara,
M. J. Organomet. Chem. 1985, 295, 265-315. (e) Yamamoto, K.; Takemae,
M. Bull. Chem. Soc. Jpn. 1989, 62, 2111-2113. (f) Funatsu, A.; Kubota,
T.; Endo, M. (Shin-Etsu Chemical Industry Co., Ltd., Japan). Jpn. Kokai
Tokkyo Koho JP2001-114788, 2001. (g) Chung, M. K.; Ferguson, G.;
Robertson, V.; Schlaf, M. Can. J. Chem.-ReV. Can. Chim. 2001, 79, 949-
957. (h) Chung, M. K.; Orlova, G.; Goddard, J. D.; Schlaf, M.; Harris, R.;
Beveridge, T. J.; White, G.; Hallett, F. R. J. Am. Chem. Soc. 2002, 124,
10508-10518. (i) Field, L. D.; Messerle, B. A.; Rehr, M.; Soler, L. P.;
Hambley, T. W. Organometallics 2003, 22, 2387-2395. (j) Biffis, A.;
Braga, M.; Basato, M. AdV. Synth. Catal. 2004, 346, 451-458.
10.1021/ol050979z CCC: $30.25
© 2005 American Chemical Society
Published on Web 06/10/2005