ENANTIOSELECTIVE ENTRY INTO BENZOXABICYCLO[2.2.1]HEPTYL SYSTEMS VIA ENZYMATIC DESYMMETRIZATION - TOWARD CHIRAL BUILDING-BLOCKS FOR LIGNAN SYNTHESIS

The meso diacetate, 9, available in seven steps from piperonal, is eff iciently desymmetrized with preferential cleavage of the R-arm-acetate under catalysis by porcine pancreatic lipase in 10% DMSO-phosphate bu ffer, pH 8. The resulting monoacetate 12, a potentially useful chiral building block for the synthesis of derivatives of the Podophyllum lig nans, is obtained in good chemical yield (66-83%) and in high optical yield (95% ee) on a multigram scale. (C) 1996 Elsevier Science Ltd