KumadaTamaoCorriu

Kumada–Tamao–Corriu coupling, also known as Kumada coupling, is a transition-metal–catalyzed cross-coupling reaction that forms carbon–carbon bonds between organohalides (such as aryl or vinyl halides) and Grignard reagents (organomagnesium halides). The reaction is typically catalyzed by nickel or palladium complexes and is valued for its relatively straightforward setup and broad substrate scope with organomagnesium reagents.

The reaction was developed independently by Kumada in 1972 and later by Tamao and Corriu, leading to the eponymous Kumada–Tamao–Corriu coupling. It represents one of the earliest nickel- and palladium-catalyzed cross-couplings and helped establish the viability of Grignard reagents as partners in catalytic C–C bond formation. Over time, refinements in ligands and catalysts expanded the range of usable substrates, though the method remains more sensitive to moisture and air than some later cross-couplings.

Mechanistically, the coupling proceeds via a catalytic cycle that typically involves oxidative addition of the organohalide to a low-valent metal center (Ni(0) or Pd(0)) to form a metal(II) aryl or vinyl species, transmetalation with the Grignard reagent, and reductive elimination to forge the new C–C bond while regenerating the active metal species. Side reactions can include homocoupling of Grignard reagents and protic quenching.

Scope and limitations: the reaction accommodates aryl and vinyl halides, and a variety of Grignard reagents, under strictly anhydrous, air-free conditions. Aryl chlorides are less reactive and sometimes require more reactive catalysts or ligands. Compared with Suzuki–Miyaura coupling, Kumada coupling often offers different reactivity patterns but generally has stricter functional-group tolerance due to the highly reactive Grignard reagents.