Programmable alkene skeleton construction via switchable radical and organometallic sorting.

The programmable synthesis of complex alkene skeletons, including regioisomers, stereoisomers and conjugated homologues in a single operation, is a long-standing goal in synthetic chemistry, given the profound influence of these structural features on molecular function. Traditional methods typically rely on predesigned substrates or rigid reaction pathways, which often restrict structural diversity. Here we report a nickel-catalysed sequential coupling of alkynes, organohalides and a diboron reagent. This method not only simultaneously achieves regioselective and unique stereoselective modulation in alkyne difunctionalization, affording uncommon 1,2-trans and 2,1-cis alkenes, but also accomplishes the construction of conjugated homologues via the controlled incorporation of two alkynes, thereby achieving the rare divergent synthesis of two conjugated diene products. Mechanistic studies reveal that the electronic properties of the ligands regulate the generation of organometallic species versus radicals, while the intrinsic metal-binding ability of the various radicals further modulates their reactivity, collectively governing product selectivity.