Direct Observation of Noninnocent Reactivity of ZnBr2 with Alkyl Halide Complexes of Nickel

Nickel-catalyzed cross-coupling reactions of alkylzinc reagents with alkyl halides (Negishi couplings) are powerful tools in synthetic organic chemistry. These reactions typically provide the coupled alkane with ZnBr 2 as the final products. We report here that generated ZnBr 2 does not always act innocently but can mediate a halogen abstraction from the nickel alkyl halide complex. Such reactivity warrants consideration in developing mechanisms and catalyst design for these versatile reactions.