Candida antarctica lipase B-catalyzed regioselective deacylation of dihydroxybenzenes acylated at both phenolic hydroxy groups

Candida antarctica lipase B proved to be highly active in the deacylation of substituted hydroquinones and resorcinols acylated at both phenolic hydroxy groups. The deacylation reactions were much faster than the corresponding direct acylations of these dihydroxybenzenes catalyzed by the same lipase. More importantly, they took place generally in a markedly regioselective manner: the acyloxy group remote from the substituent was preferentially cleaved. The main or exclusive products obtained were the regioisomers of those produced through the direct acylation of the dihydroxybenzenes. In the case of alkyl-substituted hydroquinone derivatives, the regioselectivity increased with an increase in the bulk of the substituent. In the case of 4-substituted diacylated resorcinols, the 3-O-monoacyl derivatives were obtained generally as the sole products. Quite interestingly, some secondary alcohols proved to act as better acyl acceptors than the corresponding primary alcohols in these enzymatic deacylations.