Enantioselective Organocatalytic Construction of Spiroindane Derivatives by Intramolecular Friedel–Crafts‐Type 1,4‐Addition |
| |
Authors: | Dr Keisuke Yoshida Yukihiro Itatsu Yuta Fujino Hiroki Inoue Prof?Dr Ken‐ichi Takao |
| |
Institution: | Department of Applied Chemistry, Keio University, Yokohama, Japan |
| |
Abstract: | 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. |
| |
Keywords: | asymmetric catalysis cyclization natural products organocatalysis spiro compounds |
|