Palladium‐Catalyzed Allylic Substitution: Reversible Formation of Allyl‐Bridged Dinuclear Palladium(I) Complexes

ESI-MS monitoring of the title reaction has led to the discovery that dinuclear allyl-bridged PdI complexes are formed reversibly in substantial amounts during catalysis (see scheme; Bz=benzoyl). The structure of one such complex was determined by X-ray analysis (see picture; P yellow, N blue, O red, Pd dark gray). Upon consumption of the starting materials a new dinuclear complex resulting from reductive CCl bond cleavage of CH2Cl2 was observed.