Synthesis of ω-phosphonated poly(ethylene oxide)s through the combination of kabachnik-fields reaction and “click” chemistry
Résumé
The synthesis of newx-phosphonic acid-terminatedpoly(ethylene oxide) (PEOs) monomethyl ethers was investi-gated by the combination of Atherton–Todd or Kabachnik–Fields reactions and the ‘‘click’’ copper-catalyzed 1,3-dipolarcycloaddition of azides and terminal alkynes. The Atherton–Todd route fails to give the corresponding phosphonic acid-ter-minated PEOs due to competitive cleavage of the PANbondduring the dealkylation step. In contrast, the Kabachnik–Fieldsroute leads with very good yields tox-phosphonic acid-PEOthrough ‘‘click’’ reaction of azido-PEO onto dimethyl aminopro-pargyl phosphonate prepared by Kabachnik–Fields reactionbetween propargylbenzylimine and dimethyl phosphonate,followed by acidic hydrolysis. The reported methodology, pre-cluding the use of anionic polymerization of ethylene oxide,leads to novel well-defined phosphonic acid-terminated PEOsfrom commercially available products in good yields. Moreover,such a strategy can be adapted to anchor phosphonic acid func-tionality onto a wide range of polymers.