AN APPROACH TO THE CHEMICAL SYNTHESIS OF THE NATURAL CAPSULAR POLYSACCHARIDE FROM STREPTOCOCCUS-PNEUMONIAE TYPE-3

Chemical synthesis of the heteropolysaccharide derivative [--> 4)-beta-D-Glcp(1 --> 3)-alpha,beta-D-GlcpUA(1 -->]n using the tritylcyanoethylidene condensation method is carried out. The polysaccharide consists, in average, of ten disaccharide fragments, with a 1,2-cis-glucopyranosiduronic linkage per three disaccharide units. The sodium borohydride reduction followed by deacetylation afforded glucan, consisting of glucopyranosidic units and sorbitol on the <<reducing>> end. The monomer, methyl-4-O-acetyl-3-O-(2,3,6-tri-O-acetyl-4-O-triphenylmethyl-beta-D-glucopyranosyl)-1,2-O-(1-exo - cyano)ethylidene-alpha-D-glucopyranuronate, for the polycondensation was synthesized from D-Glc. The product of the tritylcyanoethylidene condensation contains grouping(s) yielding the aromatic atom signals in H-1 and C-13 NMR spectra.