Enzymatic synthesis of dimeric and trimeric sugar-fatty acid esters

A new approach to the preparation of dimeric (gemini) and trimeric sugar fa tty acid esters has been developed. It was shown that immobilized Candida a ntarctica lipase (Novozyme) readily catalyzes acylation of 1,2:3,4-di-O-iso propylidene-D-galactopyrose and methyl-alpha-D-glucopyranoside with 2-bromo myristic acid, with the reaction rate being about three times slower than t hat observed with myristic acid. However, virtually no product was detected after incubating this enzyme with 2-bromomyristic acid and 4-O-(3',4'-O-is opropylidene-beta-D-galactopyranosyl)-2,3 :5,6-di- O-isopropylidene-1,1-di- O-methyl-D-glucose (lactose tetra-acetal) for 3 days. On the contrary, Muco r miehei lipase (Lipozyme) catalyzed the formation of 6'-O-(2-bromomyristoy l)-4-O-(3',4'-O-isopropylidene-beta-D-galactopyranosyl)-2,3:5,6-di-O-isopro pylidene-1,1-di-O-methyl-D-glucose at preparatively useful rates, although it was found to be inferior to Novozyme in the acylation of the monosacchar ide-based substrates. The products obtained after enzymatic transformation were chemically dimerised with dicarboxylic acids, and after deprotection, in the case of 1,2:3,4-di-O-isopropylidene-D-galactopyranose and lactose te tra-acetal esters, the desired gemini were obtained in reasonable overall y ields. A trimeric sugar ester surfactant was prepared in a similar fashion in just one step by reacting 6-O-(2-bromomyristoyl) methyl-alpha-D-glucosid e with 1,3,5-tris (4-carboxybutyloxy) benzene. (C) 1999 Elsevier Science In c. All rights reserved.