Enzymatic separation of hardly separable mixtures of structural isomers

Lipase-meditated separation of six hardly separable mixtures of structural isomers was carried out. It has become apparent that the hydrolysis rate of the C(5)-acetoxyl group of methyl (±)-5-acetoxy-4-aryl-(2E)-pentenoate possessing the ortho-substituents in the aromatic ring was slower than that of the corresponding compound with no substituents at the ortho-position. The hydrolysis rate of the C(5)-acetoxyl group of methyl (±)-5-acetoxy-2-aryl-(3E)-pentenoate possessing a remote reaction site from the ortho-substituents in the aromatic ring was proved to be faster than that of methyl (±)-5-acetoxy-4-aryl-(2E)-pentenoate.