Cyclocopolymerization Based on Alternating Insertions of Isocyanide and Allene Units into a Palladium-Carbon Bond

A new mode of polymerization has been developed that involves the alternating heteroinsertion of isocyanide and allene. Aryl isocyanides that contain both isocyano and allenyl moieties were designed and synthesized. The molecules rapidly polymerized in the presence of [bis(triphenylphosphino)methyl]palladium chloride through the fully alternating insertions of the isocyanide and allene moieties into a palladiumcarbon bond to afford novel polymers that contain quinoline backbones. The polymer chain was elongated by the addition of further monomer following its initial consumption, and the present polymerization is living in nature through retention of chain end active species. This is the first polymerization involving alternating incorporation of isocyanide and allene.