Kumada coupling

The Kumada coupling is a name reaction in organic chemistry. It serves the alkenylation and arylation of alkenyl or aryl halides - or triflates. There is a metal-catalyzed reaction; as catalysts nickel compounds. The reaction is named after Makoto Kumada, who published one of the first publications on this reaction. The reaction is of preparative interest, since in contrast to similar reactions such as the Suzuki or Stille coupling sp3 residues can be used.

Reaction mechanism

As a catalyst, nickel complexes are usually with phosphine ligands dppe or dppp example used. In the first step, the bromide or triflate used oxidative addition to the nickel complex. Subsequently, a transmetalation of the Grignard reagent used of magnesium on nickel takes place with magnesium bromide is formed. After the following cis- trans isomerization of the reductive elimination is carried out between the organic radicals to yield the product released, and the catalyst is formed.

In addition, nickel catalysts also expensive palladium complexes may be used.