[A convenient synthon for the synthesis of the determinant oligosaccharides Le and ABH (type 1)]

Precursors of blood group oligosaccharides ABH (type 1) and Le have been synthesized starting from benzyl 2-acetamido-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-6-O-ben zyl-2- deoxy-alpha-D-glucopyranoside after simple blocking and deblocking steps. The above disaccharide was prepared by regioselective galactosylation of benzyl 2-acetamido-6-O-benzyl-2-deoxy-alpha-D-glucopyranoside under Helferich conditions in 69% yield.