CHEMOENZYMATIC SYNTHESIS OF THE ENANTIOMERS OF IOPANOIC ACID

The two enantiomers of Iopanoic acid 1 were prepared in enantiomeric excess higher than 90\% by enzyme-catalyzed hydrolysis of precursors (+/-)-2a and (+/-)-3a, followed by standard chemical transformations. Among the tested enzymes, chymotrypsin and Lipase PS proved to be the most selective catalysts. The stereochemical outcome of the lipase-catalyzed hydrolyses of esters (+/-)-2a-d is strictly dependent upon both the size of the alkyl group attached to the chiral center and the substituent in the aromatic ring. The enantioselectivity of the reactions was evaluated by chiral HPLC and the configurations of the new products were assigned by chemical correlations.