Donor specificity and regioselectivity in Lipolase mediated acylations of methyl α-D-glucopyranoside by vinyl esters of phenolic acids and their analogues

Abstract

Methyl α-D-glucopyranoside as a model acceptor was acylated by several phenolic and non-phenolic vinyl esters using immobilised Lipolase. Donor specificity and regioselectivity of reaction were investigated. Conversion and rate of acylation by structurally varied donors indicates that the synthetic reactivity of Lipolase corresponds to the hydrolytic activity of feruloyl esterase type A. Lipolase exhibited remarkable regioselectivity for primary position of methyl α-D-glucopyranoside. The acylation occurred exclusively at 6-O primary position when vinyl esters of phenolic acids (hydroxybenzoates, hydroxyphenylalkanoates and hydroxycinnamates) served as acyl donors (5-77%). In addition to the major 6-O-acyl products (52-79%), 2,6-di-O-acylated derivatives were isolated from reaction mixtures (2-13%) when non-phenolic donors were used (vinyl esters of fully methoxylated derivatives of phenolic acids, along with vinyl benzoates, cinnamates or some heterocyclic analogues).

Keywords: Donor specificity; Feruloyl esterase activity; Glucopyranoside acylation; Lipolase; Regioselectivity.