REGIOSELECTIVE ACYLATION OF 6-DEOXY-L-HEXOSIDES AND 6-DEOXY-D-HEXOSIDES THROUGH LIPASE-CATALYZED TRANSESTERIFICATION - ENHANCED REACTIVITY OF THE 4-OH FUNCTION IN THE L SERIES

Porcine pancreatic, Candida cylindracea, and Pseudomonas fluorescens lipases, suspended in organic solvents, were used to regioselectively acylate methyl α-L- and α-D-rhamnopyranoside and methyl α-L- and α-D-fucopyranoside. While the D-sugars always gave the 2-butyrate as the main product, their L enantiomers showed a different regioselectivity; however, by proper selection of the enzyme, in the L series the rather unreactive 4-OH function could be preferentially acylated.