ENZYMATIC SOLVENT-FREE SYNTHESIS OF SUGAR ACETAL FATTY-ACID ESTERS

An enzymic solvent-free acylation of sugar acetals with a range of long-chain fatty acids (lauric, myristic, palmitic, stearic) and their methyl esters is described. The lipase-catalysed reaction was carried out at 1:1 and 2:1 molar ratios of fatty acid or methyl ester of fatty acid to sugar acetal to obtain mono- or diesters, respectively. A range of 6 monoesters of 1,2-O-isopropylidene-D-glucofuranose and 1,2:3,4-Di-O-isopropylidene-D-galactopyranose as well as 5-mono- and 3,5-diesters of 1,2-O-isopropylidene-D-xylofuranose were prepared. The synthesis was performed at 75-degrees-C in open vials or under vacuum, to provide an equilibrium shift towards the final products via evaporation of water or methanol produced in the course of the reaction. Typically yields of 50-90% were obtained under optimal conditions.