RESOLUTION OF (+/-)-TRANS-SOBREROL BY LIPASE PS-CATALYZED TRANSESTERIFICATION AND EFFECTS OF ORGANIC-SOLVENTS ON ENANTIOSELECTIVITY

Resolution of the mucolytic drug (+/-)-trans-sobrerol (1) was achieved by transesterification with vinyl acetate in organic media, catalyzed by free or immobilized Lipase PS. The enantioselectivity of the enzyme was markedly influenced by the nature of the organic solvent, but there was no correlation between enantiomeric ratio values (70-500) and either the hydrophobicity or the dielectric constant of the medium. With the enzyme immobilized onto Hyflo Super Cell and t-amyl alcohol as the solvent, the selectivity of Lipase PS for (-)-1 was extremely high and, at 50 % conversion both (-)-trans-sobrerol and (+)-trans-sobrerol monoacetate were obtained in practically 100 % optical purity.