Acid-catalysed benzylation and allylation by alkyl trichloroacetimidates

Abstract

Benzyl and allyl trichloroacetimidate (1) and (2) are convenient reagents for the O-alkylation of hydroxy groups under mildly acidic conditions, which are compatible with imide, ester, and acetal protecting groups. The base-catalyzed addition of benzyl alcohol or allyl alcohol to trichloroacetonitrile provides a simple synthesis of these imidates, but published methods for the recovery of related molecules by distillation leads to variable amounts of a rearranged product, N-alkyl trichloroacetamide. A modified procedure, suitable for the large scale synthesis of (1) and (2) without the need for a distillation step, is reported. The introduction of benzyl and allyl ethers to a variety of carbohydrate derivatives illustrates the potential of these reagents.