A decarbonylative approach to alkylnickel intermediates and C(sp)-C(sp) bond formation.

The myriad nickel-catalyzed cross-coupling reactions rely on the formation of an organonickel intermediate, but limitations in forming monoalkylnickel species have limited options for C(sp) cross-coupling. The formation of monoalkylnickel(II) species from abundant carboxylic acid esters would be valuable, but carboxylic acid derivatives are primarily decarboxylated to form alkyl radicals that lack the correct reactivity. In this work, we disclose a facile oxidative addition and decarbonylation sequence that forms monoalkylnickel(II) intermediates through a nonradical process. The key ligand, bis(4-methylpyrazole)pyridine, accelerates decarbonylation, stabilizes the alkylnickel(II) intermediate, and destabilizes off-cycle nickel(0) carbonyl species. The utility of this new reactivity in C(sp)-C(sp) bond formation is demonstrated in a reaction that is challenging by purely radical methods-the selective cross-coupling of primary carboxylic acid esters with primary alkyl iodides.