Enantioselective Organocatalytic Construction of Spiroindane Derivatives by Intramolecular Friedel-Crafts-Type 1,4-Addition.
The highly enantioselective organocatalytic construction of spiroindanes containing an all-carbon quaternary stereocenter by intramolecular Friedel-Crafts-type 1,4-addition is described. The reaction was catalyzed by a cinchonidine-based primary amine and accelerated by water and p-bromophenol. A variety of spiro compounds containing quaternary stereocenters were obtained with excellent enantioselectivity (up to 95 % ee). The reaction was applied to the asymmetric formal synthesis of the spirocyclic natural products (-)-cannabispirenones A and B.
Department of Applied Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan. yoshida@applc.keio.ac.jp.
Keisuke
K
Yoshida
Department of Applied Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.
Yukihiro
Y
Itatsu
Department of Applied Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.
Yuta
Y
Fujino
Department of Applied Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.
Hiroki
H
Inoue
Department of Applied Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan. takao@applc.keio.ac.jp.
Ken-Ichi
K
Takao
asymmetric catalysis; cyclization; natural products; organocatalysis; spiro compounds