Stable Axially Chiral Cyclohexylidenes from Catalytic Asymmetric Knoevenagel Condensation.

Abstract

Axially chiral cycloalkylidenes are interesting but less developedaxially chiral molecules. Here, a bispidine-based chiral amine catalytic system was developed to promote efficiently the asymmetric Knoevenagel condensation ofN-protected oxindoles and benzofuranones with 4-substituted cyclohexanones. A variety of alkylidenecycloalkanes with stable axial chirality were obtained in good yields with high er. Based on the absolute configuration determination of product and DFT calculations, a possible mechanism of stereoselective induction was proposed.