Regio-, Stereo-, and Enatioselective Alternating Copolymerization of Propene with Carbon Monoxide

Essentially complete regioselectivity and good catalytic activity can be achieved in the
copolymerization of propene with carbon monoxide using palladium-containing catalytic systems modified
by the basic diphosphine ligand CHdCHzP(CzH&Jz. With ~6,6'-dimethylbiphenyl-2,2'-diyl)bis(dicyclohexylphosphine)
a stereoregular poly(1-oxo-2-methyltrimethylene) was obtained. When the optically pure ligand
was used, the produced copolymer showed an intense band in the circular dichroism spectrum in the region
around 215 nm as expected for a prevailingly isotactic structure. In most cases the copolymers can be isolated
as apoly[spiro-2,5-(3-methyltetrahydrofuran)l. NMR analysis of the regioregular copolymers and comparison
with model compounds suggest that the insertion of the propene units during the growth process takes place
with primary regioselectivity.