Unified strategy for the synthesis of C-aryl glycosides

A unified approach for the synthesis of the four major groups of C-aryl glycosides has been developed. The strategy incorporates two integrated approaches, the first of which features the [4+2] cycloaddition of a glycosyl furan with a substituted benzyne followed by the acid-catalyzed opening of the resultant adduct. The second route involves the sequential palladium-catalyzed opening of a benzyne-furan cycloadduct with an iodo glycal followed by oxidation of the resultant dihydronaphthol ring and reduction of the glycal moiety. The utility of this strategy has been established by a concise formal synthesis of the C-aryl glycoside antibiotic galtamycinone.