Pd-Catalyzed Ring-Opening Polymerization of Cyclobutanols through C(sp)-C(sp) Bond Cleavage.

A new approach to ring-opening polymerization (ROP) based on C(sp)-C(sp) bond cleavage is reported. This process is based on the ability of Pd to promote both the β-carbon elimination of a bifunctional cyclobutanol precursor and the C-C coupling process with the resulting Pd-alkyl intermediate. Consequently, novel polyketone materials are obtained. Owing to the modular synthesis of the used cyclobutanol monomers, the present ROP reaction allows the introduction of substitution patterns in the polymeric chain that are not accessible by current polyketone synthesis methodologies. We have explored in detail the initiation, propagation, and termination steps of this new polymerization process.