Abstract
Formate-mediated reductive cross-couplings of vinyl halides with aryl iodides via palladium(I) catalysis occur with highly uncommon cine-substitution. The active dianionic palladium(I) catalyst, [Pd(2)I(4)][NBu(4)](2), is generated in situ from Pd(OAc)(2), Bu(4)NI, and formate. Oxidative addition of aryl iodide followed by dissociation of the dimer provides the monomeric anionic T-shaped arylpalladium(II) species, [Pd(Ar)(I)(2)(NBu(4))], which, upon vinyl halide carbopalladation, forms products of cine-substitution by way of palladium(IV) carbenes, as corroborated by deuterium-labeling experiments.