Catalytic Orthogonal Glycosylation Enabled by Enynal-Derived Copper Carbenes

Herein, we present an approach for catalytic orthogonal glycosylation utilizing earth-abundant copper carbenes. This method operates under mild conditions and employs readily accessible starting materials, including benchtop stable enynal-derived glycosyl donors, synthesized at the gram scale. The reaction accommodates a variety of glycosyl acceptors, including primary, secondary, and tertiary alcohols. The enynal-derived copper carbenes exhibit remarkable reactivity and selectivity, allowing for the formation of glycosidic linkages with different protecting groups and stereochemical patterns. This approach provides access to both 1,2-cis- and -trans-glycosidic linkages. The product stereoselectivity is independent of the anomeric configuration of the glycosyl donor, which also has orthogonal reactivity to widely used alkynes and thioglycoside donors. An iterative synthesis of a trisaccharide further demonstrates the application of this orthogonal reactivity. + image