Phosphonated furan-functionalized poly(ethylene oxide)s using orthogonal click chemistries: synthesis and Diels–Alder reactivity

The synthesis and the reactivity in Diels–Alder and retro Diels–Alder (DA/rDA) reactions of a series of novel phosphonated furan-functionalized PEO monomethyl ethers were investigated. Dimethylphosphonate-terminated furan-functionalized PEO monomethyl ethers and their phosphonic acid-terminated derivatives have been successfully prepared by using a combination of click copper-catalyzed 1,3-dipolar cycloaddition and Kabachnik–Fields reactions. Influence of both the substitution pattern of the furan ring and the solvent onto the DA/rDA process were investigated. It was found that the 3-substituted furan is the more reactive and that water facilitates both the DA and the rDA reactions, while maintaining the polymeric structure intact. The results demonstrate the potential of such structures for dynamic covalent applications and controlled drug delivery systems such as thermoreversible linkage of biological entities onto metallic nanoparticles.