The Kumada cross-coupling reaction uses a palladium or nickel catalyst to couple an organohalide and a Grignard or organolithium reagent. The mechanism follows the expected oxidative addition-reductive elimination cycle.
Lab Tips:
- Organolithium reagents are highly versatile as they can be prepared in multiple ways, including the direct lithiation of hydrocarbons.
- Fast addition of the organolithium produces α-bromo alkenyllithiums that undergo rearrangement to give lithium acetylides, lowering yields.
- No reagents should be added in excess and the Pd(0) catalyst should be clean to facilitate good yields.
- Base-sensitive functional groups are not tolerated as they will react with the Grignard or organolithium reagent. Tolerance is improved with the Negishi cross-coupling, which uses organozinc reagents instead.
Kürti, L., Czakó, B. (2005). Strategic Applications of Named Reactions in Organic Synthesis; Background and detailed mechanisms. Burlington, MA: Elsevier Academic Press.
- Reagents: Catalytic Palladium or Nickel
- Reactant: Organohalide, Organomagnesium or Organolithium
- Product: Coupled Product
- Type of Reaction: C-C Cross-Coupling
Mechanism
Original Paper
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