Improved design of inherently chiral calix[4]arenes as organocatalysts

Abstract

Improvement of the design of inherently chiral calix[4]arenes as organocatalysts was accomplished via the introduction of a diarylmethanol structure. Novel, inherently chiral calix[4]arenes bearing a tertiary amine or a quaternary ammonium moiety, together with a diarylmethanol moiety, were synthesized from previously reported chiral calix[4]arene amino acid derivatives in an optically pure form. These chiral calix[4]arenes were applied to asymmetric reactions as organocatalysts, and a positive effect of the diarylmethanol structure on enantioselectivity was observed.