Site‐Selective S‐Arylation of 1‐Thiosugars with Aryl Thianthrenium Salts through Copper(I)‐Mediated, Photoredox‐ Catalyzed Reactions

A process for the synthesis of aryl thioglycosides from the aryl thianthrenium salts and 1‐thiosugars is achieved by copper(I)‐mediated, photoredox‐catalyzed reactions. The desired products could be obtained in 32% to 78% yield after irradiation with 34 W blue light at room temperature. Various functional groups, especially including halogen groups, were well tolerated under standard reaction conditions. This strategy differs conceptually from all previous S‐glycosylations in that thiosugar functionality could be incorporated into complex natural products or drugs at a late stage site‐selectively, which has not been shown via aryl halides and aryldiazonium salts.