Organocatalyzed O-glycosylation of glycosyl trichloroacetimidates donors: L-prolinethioamide as brønsted acid catalyst

In this study, we present the utilization of L-proline-derived thioamide small organic molecules as an effective organocatalyst for the O-glycosylation of various glycosyl trichloroacetimidate donors, eliminating the need for any cocatalysts or additives. The catalytic process achieves high yields with a wide array of alcohol and sugar nucleophiles, demonstrating a broad substrate scope and operational simplicity under mild reaction conditions. Preliminary mechanistic investigations indicate that L-prolinethioamide facilitates the glycosylation reaction via Br & oslash;nsted acid/base catalysis, involving the formation of a catalyst-acceptor adduct.