Stable Axially Chiral Cyclohexylidenes from Catalytic Asymmetric Knoevenagel Condensation
Meijia Ying1, Kaixuan Wang1, Wenjun Yan1
1Key Laboratory of Green Chemistry & Technology Ministry of Education, College of Chemistry, Sichuan University, P. R. China.
Abstract:
Axially chiral cycloalkylidenes are interesting but less developed axially chiral molecules. Here, a bispidine-based chiral amine catalytic system was developed to promote efficiently the asymmetric Knoevenagel condensation of N-protected oxindoles and benzofuranones with 4-substituted cyclohexanones. A variety of alkylidenecycloalkanes with stable axial chirality were obtained in good yields and fairly good er (enantiomeric ratio). Based on the absolute configuration determination of product and DFT calculations, a possible mechanism of stereoselective induction was proposed.
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