Synthesis of a novel zwitterionic bisphosphonate cyclopolymer containing residues of alendronic acid

The reaction of 4-(diallylammonio)butanoate, H3PO3 and PCl3 in CH3SO3H created water-insoluble 4-diallylamino-1-hydroxybutylidene-1,1-bisphosphonic acid I, a novel monomer that contained residues of the osteoporosis drug alendronic acid. Monomer (±) I, a zwitterionic tetraprotic acid, in the presence of 2 equivs. NaOH(aq) and the initiator ammonium persulfate, underwent cyclopolymerization to yield water-soluble poly(zwitterion-dianion) (± =) II. Under the influence of pH, II was equilibrated to water-soluble poly(zwitterion-trianion) (± ≡) III, polytetraanion (= =) IV, poly(zwitterion-anion) (± −) V, cationic polyelectrolyte (+) VI and water-insoluble polyzwitterion (±) VII. The solution properties of backbone charges were investigated, and protonation constants of several centers in IV were determined. Polymers that contained residues of alendronic acid should have applications in various fields, including the field of medicine.