Polymer Bulletin, Vol.39, No.6, 677-684, 1997
Palladium-catalyzed three-component coupling - Polymerization of diyne, aryl dihalide, and hydride
The palladium-catalyzed three-component coupling reaction of acetylenes, aryl halides, and hydride and it＇s application to polymer synthesis are described. The coupling reaction of 1,2-diphenylacetylene, iodobenzene, and sodium diethyl benzylmalonate was carried out at 80 degrees C for 48 h in 1,4-dioxane with Pd(OAc)(2)/tri-o-tolylphosphine, from which triphenylethylene was obtained in 71% isolated yield. The benzylic hydrogen of sodium diethyl benzylmalonate was supposed to be a hydride source in the present reaction by detecting diethyl benzalmalonate in the reaction system. Based on the results, the coupling polymerization of 1,2-bis(4-phenylethynylphenyl)ethane, 4,4＇-diiodobiphenyl, and sodium diethyl benzylmalonate was carried out at 80 degrees C for 48 h to produce a polymer (M-n=8500, M-W/M-n=3.0) in high yield. Using various aryl dihalides, the corresponding polymers having trisubstituted ethylene units were also obtained in high yields.