Alpha-alkylation of ketones by addition of zinc enamides to unactivated olefins.
A zinc enamide generated from the corresponding N-aryl imine undergoes addition to an unactivated olefin, such as ethylene, 1-octene, and isobutylene, to generate an alpha-alkylated gamma-zincioimine intermediate in good to excellent yield. Terminal and gem-disubstituted olefins react with >99% regioselectivity, allowing the C-C bond formation to take place at the more hindered carbon of the double bond. The organozinc intermediate undergoes further C-C bond formation with a carbon electrophile to give, upon hydrolysis of the imine, an alpha-alkylated ketone bearing a variety of functionalized primary, secondary, and tertiary alkyl groups.
Nakamura
Masaharu
M
PRESTO, Japan Science and Technology Corporation, Department of Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. masaharu@chem.s.u-tokyo.ac.jp
Hatakeyama
Takuji
T
Nakamura
Eiichi
E