Synthesis and catalytic application of palladium pyrazolin-3-ylidene complexes

Oxidative addition of a 3-halo 1,2-disubstituted pyrazolium salt to a palladium(0) complex leads to the formation of the first reported palladium pyrazolin-3-ylidene complex. Comparison of the new system with the analogous imidazolin-2-ylidene complex in Heck catalysis shows higher yields for the new system by a factor of 2.