Short Synthesis of Phenylpropanoid Glycosides Calceolarioside A and Syringalide B

Abstract

An efficient and practical three-step synthesis of phenylpropanoid glycosides calceolarioside A and syringalide B in >62% overall yield is disclosed. The key step involves the chemoselective and regio­selective direct O-4 cinnamoylation of unprotected 2-phenylethyl-β-d-glucosides with cinnamic anhydrides using a chiral 4-pyrrolidinopyridine organocatalyst. This approach serves as a model for the short synthesis of phenylpropanoid glycosides acylated at O-4 without protection/deprotection steps.