Gold Catalysis in Glycosylation Reactions

Abstract

Glycosylation of alcohols containing acid-sensitive groups, as for example 1,2-5,6-di-O-isopropylidene-glucofuranose, Fmoc-threonine tert-butyl ester or farnesol, is achieved using gly­cosyl trichloroacetimidates activated by gold(I) chloride (5-10 mol%). While glycosylation with 2-O-acyl protected glycosyl donors proceeds with 1,2-trans-selectivity, non-neighboring group active glycosyldonors give mixtures of anomeric glycosides or α-glycosides depending upon their structure and the reactivity of the glycosyl acceptor.