ORGANIC
LETTERS
2002
Vol. 4, No. 11
1843-1845
Rhodium(I)-Catalyzed Silylation of Aryl
Halides with Triethoxysilane: Practical
Synthetic Route to Aryltriethoxysilanes
Miki Murata,* Masanori Ishikura, Masayuki Nagata, Shinji Watanabe, and
Yuzuru Masuda*
Department of Materials Science, Kitami Institute of Technology,
Kitami 090-8507, Japan
Received February 22, 2002
ABSTRACT
The specific silylation of aryl iodides and bromides with triethoxysilane (EtO)3SiH in the presence of NEt3 and a catalytic amount of [Rh-
(cod)(MeCN)2]BF4 provides the corresponding aryltriethoxysilanes in high yield.
Hypervalent siloxane derivatives, which are obtained from
aryl(trialkoxy)silanes and tetrabutylammonium fluoride, are
versatile reagents for carbon-carbon1-3 and carbon-het-
eroatom bond formation4 and provide an alternative to the
reaction of organotin or -boron compounds. Furthermore,
considerable attention has recently been paid to rhodium-
catalyzed addition of aryl(trialkoxy)silanes to carbonyl
compounds, such as aldehydes,5 R,â-unsaturated ketones, and
esters.5,6 Aryl(trialkoxy)silanes can be prepared by reacting
aryl Grignard reagents with tetraalkyl orthosilicate, but it is
difficult to prevent the formation of undesirable diaryl-
silanes.1b,2,7
Recently, we have developed the palladium(0)-catalyzed
metalation of organic halides utilizing triethoxysilanes
(EtO)3SiH (1)8 or pinacolborane9 as metalating reagents in
the presence of tertiary amines. In the case of the silylation
of aryl halides with 1 to provide aryl(triethoxy)silanes 3,
however, the electronic and steric characteristics of substrates
have a significant impact on the reactions, i.e., the starting
halides were restricted to aryl iodides having electron-
donating groups at para-position.8a Very recently, the pal-
ladium(0)-catalyzed silylation has been extended to aryl
bromides by DeShong, but the silylation of ortho-substituted
or electron-deficient aryl halides was difficult by a similar
limitation.10 During the course of our studies, we found a
new catalytic system for the silylation of aryl halides 2 with
1 (Scheme 1). We herein describe a rhodium(I)-catalyzed
silylation of 2, including aryl iodides and bromides having
electron-withdrawing groups. Recently, Berry has reported
(1) (a) Tamao, K.; Kobayashi, K.; Ito, Y. Tetrahedron Lett. 1989, 30,
6051. (b) Shibata, K.; Miyazawa, K.; Goto, Y. Chem. Commun. 1997, 1309.
(c) Mowery, M. E.; DeShong, P. J. Org. Chem. 1999, 64, 1684. (d) Mowery,
M. E.; DeShong, P. Org. Lett. 1999, 1, 2140. (e) Lee, H. M.; Nolan, S. P.
Org. Lett. 2000, 2, 2053.
(2) Aqueous NaOH can be used as an activator in place of fluoride ion.
See: Murata, M.; Shimazaki, R.; Watanabe, S.; Masuda, Y. Synthesis 2001,
2231.
(3) For general reviews for palladium-catalyzed cross-coupling reaction
of organosilicon compounds, see: (a) Hatanaka, Y.; Hiyama, T. Synlett
1991, 845. (b) Hiyama, T. In Metal-catalyzed Cross-coupling Reactions;
Diederich, F., Stang, P. J., Eds.; Wiley-VCH: Weinhein, 1998; p 421. (c)
Hiyama, T.; Shirakawa, E. In Topics in Current Chemistry; Miyaura, N.,
Ed.; Springer-Verlag: Heidelberg, 2002; Vol. 219, p 61.
(4) (a) Lam, P. Y. S.; Deudon, S.; Averill, K. M.; Li, R.; He, M. Y.;
DeShong, P.; Clark, C. G. J. Am. Chem. Soc. 2000, 122, 7600. (b) Lam, P.
Y. S.; Deudon, S.; Hauptman, E.; Clark, C. G. Tetrahedron Lett. 2001, 42,
2427.
(6) Oi, S.; Honma, Y.; Inoue, Y. Org. Lett. 2002, 4, 669.
(7) (a) Chappelow, C. C.; Elliott, R. L.; Goodwin, J. T., Jr. J. Org. Chem.
1960, 25, 435. (b) Selin, T. G.; West, R. J. Am. Chem. Soc. 1962, 84, 1856.
(8) (a) Murata, M.; Suzuki, K.; Watanabe, S.; Masuda, Y. J. Org. Chem.
1997, 62, 8569. (b) Murata, M.; Watanabe, S.; Masuda, Y. Tetrahedron
Lett. 1999, 40, 9255.
(9) (a) Murata, M.; Watanabe, S.; Masuda, Y. J. Org. Chem. 1997, 62,
6458. (b) Murata, M.; Oyama, T.; Watanabe, S.; Masuda, Y. J. Org. Chem.
2000, 65, 164. (c) Murata, M.; Oyama, T.; Watanabe, S.; Masuda, Y.
Synthesis 2000, 778. (d) Murata, M.; Watanabe, S.; Masuda, Y. Tetrahedron
Lett. 2000, 41, 5877.
(5) Murata, M.; Shimazaki, R.; Ishikura, M.; Watanabe, S.; Masuda, Y.
Synthesis, in press.
(10) Manoso, A. S.; DeShong, P. J. Org. Chem. 2001, 66, 7449.
10.1021/ol025770p CCC: $22.00 © 2002 American Chemical Society
Published on Web 05/03/2002