The reactivity of polychlorobenzenes vs. polyfluorobenzenes for palladium-catalysed direct arylation was studied. The PdCl(C3H5)(dppb)/KOAc system was found to promote the direct arylation of some polychlorobenzenes with aryl bromides. However, the reactivity of polychlorobenzenes was found to be lower than that of polyfluorobenzenes. The best yields were obtained from the coupling of 1,2,4,5-tetrachlorobenzene or 1,3,5-trichlorobenzene with electron-deficient aryl bromides. The C3 arylation of 2,5-dichlorothiophene was also found to proceed nicely.
