Enzymatic optical resolution of norbornanecarboxylic esters using pig liver esterase

The hydrolysis of a series of norbornane‐type carboxylic esters catalyzed by pig liver esterase (PLE) has been investigated. It was found that an exo‐eer function (syn to the C7 methylene group) is hydrolyzed with high preference. Enantioselective hydrolysis can be accomplished when a vicinal carbonyl‐containing function (eer, formyl, acetyl) is present in a trans position with respect to the exo eer. The regiospecificity of the enzymatic hydrolysis has been used for the separation of exo/endo mixtures of the cycloadducts derived from cyclopentadiene and alkene esters. The regiospecificity and enantioselectivity of the enzymatic hydrolysis of norbornane‐type esters were analyzed in terms of Tamm's substrate model and also by Griengl's method.