A highly efficient palladium-catalyzed synthesis of unsym. substituted 3-(diarylmethylenyl)indolinones from readily accessible starting materials is developed. The domino reaction involves a sequence of intermol. carbopalladation, C-H activation, and C-C bond formation. A plausible mechanistic pathway for the reaction is discussed on the basis of the kinetic isotope effect [KH/KD (intermol.) = 1, KH/KD (intramol.) = 2.7] as well as the electronic effect. [on SciFinder (R)]