The present invention relates 5 to novel oligomers of Neisseria meningitidis serogroup Y capsular polysaccharide repeating unit (Men- Y oligomers) and process for synthesizing novel Men- Y oligomers. In particular, the present invention relates to the chemical synthesis of the tetramer of Men- Y capsular 10 polysaccharide repeating unit capable of being used as a candidate in the development of semisynthetic or fully synthetic conjugate vaccine against meningococcal serogroup Y bacterial infection.
