Stereocontrolled Synthesis of 2-Deoxy- C-glycopyranosyl Arenes Using Glycals and Aromatic Amines.

An efficient and stereoselective one-pot, two-step tandem α-arylation of glycals from readily available aryl amines via stable diazonium salts has been developed. Moreover, the stereoselective preparation of the challenging β- C-glycosyl arenes by the anomerization of α- C-glycosides using HBF4 is also described. This protocol has a broad substrate scope and a wide functional-group tolerance. It can be used for the gram-scale preparation of 3-oxo- C-glycosides, which are versatile substrates for the preparation of many biologically important C-glycosides.