In(OTf)3-Only-Catalyzed Glycosylation via Activation of an Alkyne Appended with an Amide Auxiliary Group

We herein present the development of a novel glycosylation protocol using glycosyl o-N-(o-methoxybenzamidoyl)-propynyl benzoates as donors, activated solely by a catalytic amount of In(OTf)3, eliminating the need for a Au(I) catalyst. This approach offers mild and orthogonal conditions, enabling glycosylation across a broad substrate scope and facilitating versatile one-pot strategies for glycan assembly. Mechanistic insights suggest that In(OTf)3 serves dual roles by being recruited to the auxiliary group through σ-coordination while activating the alkyne via π-interaction.