Leaves from oak (Quercus robur) contain an acyltransferase that catalyzes the conversion of β-glucogallin (1-O-galloyl-β-D-glucose) to 1,6-di-O-galloylglucose, an intermediate in the biosynthesis of gallotannins. Substrate specificity studies revealed th at this enzyme was also active with several structurally related 1-O-phenylcarboxyl-β-D-glucoses; appreciable reaction rates, however, were observed only in the form ation of 1,6-di-O-protocatechuoyl-β-D-glucose. This to date unknown ester, as well as its digalloyl analog, was synthesized using acyltransferase immobilized on phenyl-Sepharose, and characterized by UV and 1 H NMR spectroscopy. In addition, the 1,2-di-O-β-D-glucose esters of benzoic and anisic acid were obtained in this investigation.