Lipase-catalyzed regioselective acylation of tritylglycosides in supercritical carbon dioxide

Abstract

Candida rugosa lipase (CRL) was used to catalyze the regioselective acylation of methyl 6- O-trityl β- d-glucopyranoside in supercritical CO 2 (SCCO 2), using vinyl acetate as the acyl donor and obtained final conversion values up to 91.4%. The effect of pressure, temperature, enzyme quantity and sugar/ester molar ratio on the catalytic efficiency and regioselectivity of CRL was evaluated. The regioselectivity of the reaction was shifted towards the synthesis of 3- O-acetyl 6- O-trityl β- d-glucopyranoside and this is a function of the chemico-physical parameters of the supercritical medium employed. In fact, by varying the CO 2 pressure used in the process up to 20 MPa at constant temperature, we were able to obtain the formation of the sole 3- O-acetyl 6- O-trityl β- d-glucopyranoside regioisomer. A kinetic study was also performed and the relative kinetic parameters calculated.