Regioselective Benzoylation of 4,6-O-Benzylidene Acetals of Glycopyranosides in the Presence of Transition Metals

GRAPHICAL ABSTRACT

Abstract

Benzoylation of 4,6-O-benzylidene acetals of glycopyranosides by benzoic anhydride in acetonitrile in the presence of Cu(CF₃COO)₂ as a promoter gave 2-benzoates for α-D-glucopyranosides and α-D-mannopyranosides and 3-benzoates for β-D-galactopyranosides in good yields with high regioselectivity. Benzoylation of 4,6-O-benzylidene acetals of glycopyranosides of D-galactose and D-mannose by benzoyl chloride in the presence of MoO₂(acac)₂ as a catalyst in all studied cases led to regioselective 3-О-substitution.

Keywords:

• 4,6-O-benzylidene acetals
• Copper (II) trifluoroacetate
• Molybdenum (VI) dioxide bis(acetylacetonate)
• Regioselective benzoylation