Enantioselective alternating copolymerization of alpha-olefins with carbonmonoxide using a cationic palladium-chiral diphosphine complex

Enantioselective alternating copolymerization of carbon monoxide with propy lene, 1-heptene, 1-octene, and styrene was carried out using a palladium ca talyst modified by 1,4-3,6-dianhydro-2,5-dideoxy-2,5-bis(diphenylphosphino) -L-iditol (DDPPI). The chiral diphosphine was proved to be effective for en antioselective copolymerization. The pure poly(1,4-ketone)s were obtained b y dissolving the copolymers containing spiroketal and 1,4-ketone units in 1 ,1,1,3,3,3-hexafluoro-2-propanol and reprecipitating with methanol. Optical rotation, elemental analysis, and H-1 NMR, C-13 NMR, and IR spectra showed that our copolymers were optically active, isotactic, alternating poly(1,4 -ketone) structures. An oxidant and a weakly or noncoordinating anion were important in the copolymerization.