Tetranuclear zinc cluster: a dual purpose catalyst for per-O-acetylation and de-O-acetylation of carbohydrates

Abstract

The trifluoroacetic acid adduct of tetranuclear zinc cluster Zn₄(OCOCF₃)₆O catalysis in per-O-acetylation and de-O-acetylation of carbohydrates at 70 °C can be tuned by adjusting the reaction medium. Per-O-acetylation of hexopyranoses with a near stoichiometric amount of acetic anhydride in toluene resulted in the exclusive formation of pyranosyl products as an anomeric mixture, whereas de-O-acetylation of acetates occurred in methanol in high yields. In the latter, methanol acts as both nucleophile and solvent, and the reaction conditions were compatible to acid- and base-sensitive groups and amino acid derivatives.