Off-Template Claisen Rearrangement of a D-Glucose-Derived Bicyclic Substrate

Abstract

The Claisen rearrangement of branched-chain furanose 5, which has an allylic alcohol function as a side chain, by heating in triethyl orthoacetate afforded a diastereomeric mixture 6 of the rearrangement products. The ratio of the products was estimated to be nearly 3:1 based on the ¹H NMR analysis. The configuration at the newly introduced chiral center in each product was established by chemical conversion of the mixture 6 to tricyclic products 13R and 13S. The preferential formation of the rearrangement product having R-configuration at the newly formed chiral center was rationalized by consideration of the chair-like transition states.