Herein we investigate the scope and limitations of a new synthetic approach towards α‐ and β‐ketopyranosides relying on the functionalization of the anomeric CH bond of carbohydrates by insertion of a metal carbene. A key bromoacetate grafted at the 2‐position is the cornerstone of a stereoselective glycosylation/diazotransfer/quaternarization sequence that makes possible the construction of a quaternary