Photocatalytic Synthesis of α-Ketonyl Glycosyl Compounds from Glycosyl Thiols and Silyl Enol Ethers.

The synthesis of C1-ketonyl glycosyl compounds featuring α-selectivity has seldom been reported. We herein devise a glycosyl radical-based approach to facilely access stereoenriched ketonyl glycosyl compounds via an Ir photoredox-catalyzed desulfurative addition to silyl enol ethers, using in situ-generated tetrafluoropyridinyl thioglycosides from glycosyl 1-thiols as radical precursors. This protocol features readily prepared starting materials, mild conditions, excellent functional group tolerance, satisfactory scale-up, and notable amenability to late-stage modification of pharmaceutically relevant complex molecules.