Click chemistry with poly(2-oxazoline)s

A new 2-oxazoline with a pendant alkyne moiety, 2-(pent-4-ynyl)-2-oxazoline, 1 (PynOx), was synthesized from commercial available compounds. Polymerization of PynOx with methyl triflate as initiator and copolymerization with 2-methyl- or 2-ethyl-2-oxazoline (MeOx or EtOx) as comonomers results in well-defined water-soluble polymers of narrow molar mass distributions and predefined degrees of polymerization. Since the alkyne moiety is compatible with the living cationic polymerization, no protection group was needed. The consecutive copper-catalyzed Huisgen 1,3-dipolar cycloadditions of two different azides with the polymer bound alkynes to the 1,2,3-triazoles were quantitative.