Synthesis of N,O-type inherently chiral calix[4]arenes substituted on the lower rim and their organocatalysis properties

Abstract

This work presented the first study of organocatalytic behaviors of inherently chiral calix[4] arenes substituted at the lower rim. A pair of N,O-type enantiomers based on inherently chiral calix[4]arenes substituted at the lower rim were readily synthesized and applied to catalyze Henry reaction between aromatic aldehydes and nitromethane. Their organocatalytic reaction can afford the desired products in excellent yields (up to 99%) but poor enantioselectivities (up to 7.5% ee).