ORGANIC
LETTERS
2005
Vol. 7, No. 21
4725-4728
Copper-Catalyzed Allylation of Carbonyl
Derivatives Using Allyl(2-pyridyl)silanes
Toshiyuki Kamei, Kazuyoshi Fujita, Kenichiro Itami,*,† and Jun-ichi Yoshida*
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of
Engineering, Kyoto UniVersity, Nishikyo-ku, Kyoto 615-8510, Japan
itami@chem.nagoya-u.ac.jp; yoshida@sbchem.kyoto-u.ac.jp
Received August 10, 2005
ABSTRACT
We have developed an efficient copper-catalyzed allylation of carbonyl derivatives using allyl(2-pyridyl)silanes, in which the strong directing
effect of the 2-pyridyl group was observed. A useful synthesis and allylation of substituted allyl(2-pyridyl)silanes is also described.
Over the last three decades of extensive worldwide research,
the addition reaction of allylmetals to CdZ bonds (Z ) O
or NR) has emerged as one of the most useful carbon-carbon
bond-forming reactions.1 Although it has now become a
textbook reaction in organic synthesis, there still exists
considerable room for further development and improvement.
As a part of our studies using a 2-pyridylsilyl group as a
“removable directing group” in metal catalysis,2 we previ-
ously reported the AgOAc-catalyzed allylation of aldehydes
using allyldimethyl(2-pyridyl)silane (1).3 Though interesting
from a mechanistic point of view (most likely via Lewis base
activation mechanism), the reaction suffered severely from
limited scope. We herein report a unique copper catalysis in
the allylation using 1, where a wide range of carbonyl
derivatives, including ketones and imines, can be applied.
A useful synthesis and allylation of substituted allyl(2-
pyridyl)silanes is also described.
During our study aimed at developing reliable allylation
using 1, we found that the allylation of benzaldehyde (2a,
1.0 equiv) using 1 (1.2 equiv) proceeded smoothly even at
room temperature under the influence of CuI (10 mol %)
and CsF (2.0 equiv) in THF, giving homoallylic alcohol 3a
in 86% yield after acidic workup (Table 1, entry 1). The
Table 1. Effect of Copper Salts in the Allylation of 2a Using 1
† Current address: Research Center for Materials Science, Nagoya
University, Nagoya 464-8602, Japan.
(1) Reviews: (a) Yamamoto, Y.; Asao, N. Chem. ReV. 1993, 93, 2207.
(b) Denmark, S. E.; Fu, J. Chem. ReV. 2003, 103, 2763. (b) Kennedy, J. W.
J.; Hall, D. G. Angew. Chem., Int. Ed. 2003, 42, 4732.
(2) Selected examples: (a) Itami, K.; Mitsudo, K.; Kamei, T.; Koike,
T.; Nokami, T.; Yoshida, J. J. Am. Chem. Soc. 2000, 122, 12013. (b) Itami,
K.; Nokami, T.; Yoshida, J. J. Am. Chem. Soc. 2001, 123, 5600. (c) Itami,
K.; Koike, T.; Yoshida, J. J. Am. Chem. Soc. 2001, 123, 6957. (d) Itami,
K.; Kamei, T.; Yoshida, J. J. Am. Chem. Soc. 2001, 123, 8773. (e) Itami,
K.; Nokami, T.; Ishimura, Y.; Mitsudo, K.; Kamei, T.; Yoshida, J. J. Am.
Chem. Soc. 2001, 123, 11577. (f) Itami, K.; Kamei, T.; Yoshida, J. J. Am.
Chem. Soc. 2003, 125, 14670. (g) Itami, K.; Mitsudo, K.; Fujita, K.; Ohashi,
Y.; Yoshida, J. J. Am. Chem. Soc. 2004, 126, 11058.
results using various copper salts are depicted in Table 1.
The omission of either promoter (CuI or CsF) completely
failed to promote the reaction (entries 2 and 3). Other copper-
(I) salts, such as CuBr, CuCl, and CuCN, also promoted this
allylation, but the efficacy was somewhat lower than that of
CuI (entries 6-8). Interestingly, the cationic copper(I)
(3) Itami, K.; Kamei, T.; Mineno, M.; Yoshida, J. Chem. Lett. 2002,
1084.
10.1021/ol051925s CCC: $30.25
© 2005 American Chemical Society
Published on Web 09/22/2005