Chiral Primary Amine Organocatalysts for Syn-selective Asymmetric Cross-Aldol Reactions

Abstract

Based on the “acid-base” interaction strategy, organocatalysts for the asymmetric cross-aldol reaction were synthesized by the in situ combination of chiral primary amines with protonic acids. Unlike general secondary amine catalysts that give anti -selective products, as-prepared primary amine catalysts can give syn -selective cross-aldol products with high yield and high selectivity (up to 90% yield, 90:10 syn / anti ratio, 90% ee). Compared with the complex synthesis of the reported catalysts, the primary amine catalyst that gave the best results was easily prepared using commercial available (1 S ,2 S )-(+)-cyclohexanediamine.