A. Safir, B. Novak
Jan 16, 1998
Citations
0
Influential Citations
23
Citations
Journal
Journal of the American Chemical Society
Abstract
The alternating copolymerizations of carbon monoxide with the electron-poor bicyclic olefins, diethyl bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate (1) and diethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate (2), is achieved with neutral palladium(II) initiators. These Pd(II) complexes utilize a σ,π-alkyl ligand, a halide anion, and 1 equiv of a stabilizing donor ligand (pyridine or triphenylphosphine). The preferred catalyst, due to reactivity and stability, is iodo(endo-6-phenyl-2-norbornene-endo-5σ,2π)(triphenylphosphine)palladium(II) (6). This initiator produces living copolymerizations of 1 with CO in the presence of H2O and O2. The polymer isolated, poly(1-alt-CO), retains the Pd as the endgroup, and can be used to reinitiate copolymerization leading to chain extension or diblock copolymer formation. Both of the copolymers poly(1-alt-CO) and poly-(2-alt-CO) undergo retro Diels−Alder reaction to produce furan derivative 7 and a new cross-conjugated material, poly(ketovinylene) (PKV). While...