Application of Redox-Active Ester Catalysis to the Synthesis of Pyranose Alkyl C -Glycosides.

The direct coupling of shelf-stable, tetrachloro--hydroxyphthalimide ester (TCNHPI) glycosyl donors with a variety of alkylzinc reagents under redox catalysis is described. Alkyl -glycosides are formed directly by a decarboxylative, Negishi-type process in 31-73% yields without the need for photocatalytic activation or additional reductants. Extension of this approach to the coupling of TCNHPI donors with stereodefined α-alkoxy furan-containing alkylzinc halides enabled synthesis of methylene-linked -disaccharides via an Achmatowicz rearrangement.