Solvent-free benzylation of polyols by phase-transfer catalysis or supported reagent methods

Solvent-free techniques were successfully and efficiently applied under mild conditions to the perbenzylation of methyl α- d -glucopyranoside and methyl 6-bromo(and 6-chloro)-6-deoxy-α- d -glucopyranoside, and to the selective monobenzylation of diethyl (R,R)-tartrate. Selective 2-O- or 3-O-benzylation of methyl 4,6-O-benzylidene-α- d -galactopyranoside, requiring CH2Cl2 as solvent, was observed depending on the nature of the ammonium catalyst.