Application of Redox-Active Ester Catalysis to the Synthesis of Pyranose Alkyl <i>C</i>-Glycosides

Abstract

The direct coupling of shelf-stable, tetrachloro-<i>N</i>-hydroxyphthalimide ester (TCNHPI) glycosyl donors with a variety of alkylzinc reagents under redox catalysis is described. Alkyl <i>C</i>-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 <i>de novo</i> synthesis of methylene-linked <i>exo-C</i>-disaccharides via an Achmatowicz rearrangement.