A method to synthesize benzyl group protected alpha-pentagalloylglucose (.alpha.-PGG) and related compounds. The method comprises the steps of: suspending a highly reactive acylation agent and an acylating catalyst in a donor solvent; adding .alpha.-D-glucose or an analogue thereof to the mixture; reacting the mixture at room temperature for a time sufficient for reaction to occur; evaporating the solvent; taking up the residue in an appropriate solvent; filtering the residue and solvent mixture; and evaporating off the solvent.