Unsaturated carbohydrates. Part XVII. Synthesis of branched-chain sugar derivatives by application of the Claisen rearrangement

Abstract

2,3-Dideoxy-4-O-vinylhex-2-enopyranoside derivatives on heating to 180° undergo the Claisen rearrangement to give 2,3,4-trideoxy-2-C-(formylmethyl)hex-3-enopyranoside isomers. Suprafacial [3,3] sigmatropic processes are involved, so that stereochemical integrity is maintained at the allylic centres. The reaction represents a novel means whereby branch points can be introduced into carbohydrates.