A facile protocol for direct conversion of unprotected sugars into phenyl 4,6-O-benzylidene-per-O-acetylated-1,2-trans-thioglycosides

A short and practical methodology for conversion of unprotected d-glucose, maltose, cellobiose and lactose into the corresponding phenyl 4,6-O-benzylidine-per-O-acetylated-1,2-trans-thioglycosides is described. The protocol is based on the execution of five reaction steps (bromoacetylation, thiophenolysis under phase transfer catalysis conditions, deacetylation, benzylidenation and acetylation) in one continuous procedure and provides a fast access to the title compounds as pure crystalline products without chromatographic purification.