STEREOSPECIFIC CHEMOENZYMATIC SYNTHESIS OF GALACTOPYRANOSYL-L-SERINE

The transglycosylation from raffinose and lactose to Aloc-Ser-OMe is catalyzed respectively by a and beta-galactosidases. The simplicity of the enzymatic synthesis. the stereospecificity of the condensations in one-pot reactions and the ease of purification give the method value for large scale preparation of beta-linked derivatives. The protective groups of the serine residue can be cleaved under mild conditions: the ester group has been removed quantitatively by papain catalyzed hydrolysis and the Aloc group by a Pd (0) hydrostannolytic cleavage.