First synthesis of poly(acylmethylene)s via palladium-mediated polymerization of diazoketones

Palladium-mediated polymerization of diazoketones (1a, 2a, 3a, 4a, and 6a) proceeded to give poly(acylmethylene)s (1b, 2b, 3b, 4b, and 6b), in which all of the main chain carbons had acyl groups. The structures of the novel polymers were characterized by NMR spectroscopy, elemental analyses, and molecular weight measurements (GPC and VPO), where the results of the elemental analyses suggested incorporation of a small amount of azo group (-N=N-) into the main chain (ca. one -N=N- per polymer chain). The presence of a C=C double bond adjacent to the carbonyl carbon in the monomers was required for the polymerization to proceed. Palladium-mediated copolymerizations using a variety of combinations of diazoketones and ethyl diazoacetate, 8, as comonomers proceeded to give various poly(substituted methylene)s.