One-Pot Regioselective Diacylation of Pyranoside 1,2- cis Diols.

A one-pot strategy for functionalizing pyranoside 1,2- cis -diols with two different ester protecting groups is reported. The approach employs regioselective acylation via orthoester hydrolysis promoted by a carboxylic acid, e.g., levulinic acid, acetic acid, benzoic acid, or chloroacetic acid. Upon removal of water and introduction of a coupling agent, the carboxylic acid is esterified to the hydroxyl group liberated during hydrolysis. Although applied to 1,2- cis -diols on pyranoside scaffolds, the method should be applicable to such motifs on any six-membered ring.