Pd(II)-catalyzed copolymerization of a norbornadiene derivative with substituted phenylacetylenes

Copolymerizations of diethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate (DOHDD) with phenylacetylene (PA) or p-methoxyphenylacetylene (MeOPA) were successfully performed in chloroform using PdBr2 as catalyst. The products of reactivity ratios r1 · r2 for poly(DOHDD-co-PA) and poly(DOHDD-co-MeOPA) are 0.026 and 0.0077, respectively. These values suggest a maximum degree of alternating sequences of 86 and 92% in the two systems, hence a high alternating tendency. It is interesting to note that the present copolymerizations occur by combination of different types of monomer, alkene and alkyne.