A new strategy for liquid-phase synthesis of disaccharides based on the use of glycosidases

A new strategy for the glycosidase-catalyzed liquid-phase synthesis of olig osaccharides, which facilitates the purification of the products, is descri bed. This strategy is based on the use of glycosidases in two key steps: (i ) glycosidation of a sugar bound to a soluble-support, and (ii) specific re moval of the unreacted monosaccharide acceptor. Glucose is attached to the MPEG support through a linker derived from valeric acid. The introduction o f the linker moiety was performed by an O-anomeric alkylation reaction. The galactosylation of the glucose-bound to the soluble-support using beta-gal actosidase gave, after removal of by-products by precipitation and filtrati on of the support, galactosyl-glucose disaccharides bound to MPEG. Finally the alkylated disaccharides were released from the MPEG by ethanolysis. Unr eacted glucose could be removed from the support by hydrolysis using glucos idases.