Brønsted acid-catalyzed ring-opening polycondensation of galactose-based cyclic sulfite

摘要

We performed cationic ring-opening polycondensation of a galactose-based cyclic sulfite monomer to give (1?→?2)-galactan. Treatment of the cyclic sulfite with 10-(+)-camphorsulfonic acid (CSA) in the presence of water initiated ring-opening polycondensation to give benzylated (1?→?2)-galactan. The MALDI-TOF mass spectrum of the obtained polymer showed a simple pattern with even intervals, indicating the formation of benzylated (1?→?2)-galactan with OH termini. When we used 4-penten-1-ol as the alcohol initiator for cationic polycondensation, we obtained a pentenoyl group-terminated polymer and/or cyclic oligosaccharides. The mechanism for the polycondensation reaction was determine through systematic investigations of the polymerization and DOSY spectral measurements of the polymer. The present method may be useful with graft polymerizations designed to give oligogalactan-containing glycosides in one pot.