Synthesis of C-Alkynyl Glycosides by Photoredox-Catalyzed Reductive Coupling of Alkynyl Bromides with Glycosyl Bromides.

A general, convenient, and highly α stereoselective approach to access C-alkynyl glycosides via the photoredox-catalyzed reductive coupling of alkynyl bromides and glycoside bromides has been developed. Cheap and small-load eosin Y is used as the photocatalyst, and organic base N,N-diisopropylethylamine serves as the reducing reagent. This strategy features readily available starting materials, diverse substrates, mild conditions, and high α stereoselectivity. Moreover, a glycoconjugated peptide could also be achieved using this strategy.