Cp(π-Allyl)Pd-Initiated Polymerization of Diazoacetates: Reaction Development, Kinetic Study, and Chain Transfer with Alcohols

A new initiating system, (cyclopentadienyl) (π-allyl)palladium(II) [Cp(π-allyl)Pd], for the polymerization of diazoacetate monomers has been developed. Homo- and copolymers bearing an ester substituent at every main-chain carbon atom were efficiently synthesized from various alkyl and aryl diazoacetates. In particular, this polymerization system can tolerate various functional groups, which allows for effective postpolymerization functionalization of the resultant polymers. Detailed kinetic study indicates that this polymerization has the characteristics of slow initiation and rapid propagation. Furthermore, alcohols were found to function as chain transfer agents as confirmed by polymerization experiments and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analyses of the polymer products, thus providing an effective method for controlling the molecular weight of the polymer.