POTENTIAL APPLICATIONS OF ENZYME-MEDIATED TRANSESTERIFICATIONS IN THE SYNTHESIS OF BIOACTIVE COMPOUNDS

The yeast lipase Candida cylindracea (CCL) and porcine pancreatic lipase (PPL) have been used for regioselective deacylation of peracetylated benzopyrones, diphenylpropenones and acetophenones for the first time. The deacylation study on different classes of polyphenols has revealed that the presence of carbonyl group attached to the aromatic ring is needed by the lipases to exhibit regioselectivity towards hydrolysis of acetoxyl groups. The acetoxyl groups at positions other than the one at ortho position to the carbonyl group get selectively hydrolysed by PPL in organic solvents. The transesterification reactions using triflouroethylbutyrate (TFEB), catalysed by PPL and CCL on some polyols in dry organic solvents were also performed. It was found that the primary hydroxyl is acylated. In D-panthenol, the oxidised dextrorotatory form of which is a major constituent of vitamin B-complex, the primary hydroxyl group at the far end of the asymmetric carbon atom gets exclusively acylated. This work should be of importance in the synthesis of building blocks of biologically active natural products which may provide structural leads to anti AIDS and anticancer agents.