SYNTHESIS OF THE TETRASACCHARIDE REPEATING UNIT OF THE ANTIGEN FROM KLEBSIELLA TYPE-20

Starting from D-mannose, D-galactose and D-glucuronolactone, two disaccharide blocks, namely methyl 4,6-di-O-benzyl-2-O-(2,3,4,6-tetra-O-benzyl-beta-D-galactopyranosyl)-alpha-D-mannopyranoside, acting as acceptor, and ethyl 4,6-di-O-acetyl-2-O-allyl-3-O-(methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyluronate)-1-thio-beta-D-galactopyranoside, acting as donor, were synthesised. The two disaccharides were then allowed to react to give, after deprotection, methyl 2-O-beta-D-galactopyranosyl-3-O-(3-O-beta-D-glucopyranosyluronic acid-alpha-D-galactopyranosyl)-alpha-D-mannopyranoside which is the methyl glycoside of the tetrasaccharide repeating unit of the said antigen.