Gold(I)-Catalyzed Access to 1-Alkynyl C-Glycosides from 1-Silylated Alkynes: An Alternative Paradigm for the Direct and α-Stereoselective Alkynylation of Glycosides

Analogous to O -glycosides, C -glycosides are natural products exhibiting various bioactivities. Alkynyl C -glycosides represent important key intermediates toward more complex derivatives; however, a convenient access through a single catalytic and highly stereocontrolled step remains an important and only partially solved challenge. Here, a mechanistically designed gold(I)-catalyzed silyl-assisted efficient and highly α-stereoselective process is reported. The postulated mechanism has been ascertained by combining 1 H, 31 P and VT NMR and in situ MS experiments.