Synthesis of structures corresponding to the capsular polysaccharide of Neisseria meningitidis group A

Four differently substituted trimers of the CPS repeating unit have been synthesised in order to investigate the dependence on oligosaccharide size, acetylation and mode of phosphorylation of glycoconjugate vaccines against Neisseria meningitidis group A. A spacer-containing starting monomer, a H-phosphonate elongating monomer and a 6-O-phosphorylated H-phosphonate cap monomer have been synthesised and coupled together to afford, after deprotection, the target trimer structures differing in their acetylation and phosphorylation substitution pattern.