Synthesis of methyl 3-O-α-d-galactopyranosyl-6-O-α-d-mannopyranosyl-α-d-mannopyranoside,methyl 3-O-α-d-glucopyranosyl-6-O-α-d-mannopyranosyl-α-d-mannopyranoside,methyl 6-O-α-d-galactopyranosyl-3-O-α-d-mannopyranosyl-α-d-mannopyranoside,and methyl 6-O-α-d-glucopyranosyl-3-O-α-d-mannopyranosyl-α-d-mannopyranoside |