Formation of Glycosyl Trichloroacetamides from Trichloroacetimidate Donors Occurs through an Intermolecular Aglycon Transfer Reaction.

Abstract

To probe the reaction mechanism, underlying the rearrangement of oft-used trichloroacetimidate glycosyl donors into the corresponding anomeric trichloroacetamides, we have used a combination of 13C- and 15N-labeled glycosyl trichloroacetimidate donors in a series of crossover experiments. These unambiguously show that trichloroacetamides are formed via an intermolecular aglycon transfer mechanism. This insight enables the design of more effective glycosylation protocols, preventing the formation of dead-end side products.