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Title= Suzuki Coupling

Mechanism
The mechanism if the reaction as follows

Oxidative addition
The mechanism if the reaction as follows

The Suzuki reaction is the organic reaction of an aryl- or vinyl-boronic acid with an aryl- or vinyl-halide catalyzed by a palladium(0) complex. It is widely used to synthesize poly-olefins, styrenes, and substituted biphenyls, and has been extended to incorporate alkyl bromides. Several reviews have been published.



The reaction also works with pseudohalides, such as triflates (OTf), instead of halides. Boronic esters and organotrifluoroborate salts may be used instead of boronic acids.


 * Relative reactivity: R2-I > R2-OTf > R2-Br >> R2-Cl

First published in 1979 by Akira Suzuki, the Suzuki reaction couples boronic acids (containing an organic part) to halides. The reaction relies on a palladium catalyst such as tetrakis(triphenylphosphine)palladium(0) to effect part of the transformation. The palladium catalyst (more strictly a pre-catalyst) is 4-coordinate, and usually involves phosphine supporting groups.

The 2010 Nobel Prize in Chemistry was awarded to Suzuki for his discovery and development of this reaction. In many publications this reaction also goes by the name Suzuki-Miyaura reaction. It is also often referred to as "Suzuki Coupling".

Reaction mechanism
The mechanism of the Suzuki reaction is best viewed from the perspective of the palladium catalyst. The first step is the oxidative addition of palladium to the halide 2 to form the organopalladium species 3. Reaction with base gives intermediate 4, which via transmetalation with the boron-ate complex 6 forms the organopalladium species 8. Reductive elimination of the desired product 9 restores the original palladium catalyst 1.



Oxidative addition
Oxidative addition proceeds with retention of stereochemistry with vinyl halides, while giving inversion of stereochemistry with allylic and benzylic halides. The oxidative addition initially forms the cis-palladium complex, which rapidly isomerizes to the trans-complex.

Reductive elimination
Using deuterium-labelling, Ridgway et al. have shown the reductive elimination proceeds with retention of stereochemistry. Relative reactivity of different metal complexes in the C-C reductive elimination was established: Pd(IV), Pd(II) > Pt(IV), Pt(II), Rh(III) > Ir(III), Ru(II), Os(II).

Scope
The Suzuki coupling has been used on a citronellal derivative for the synthesis of caparratriene, a natural product that is highly active against leukemia:



Recent applications of the Suzuki–Miyaura cross-coupling reaction in organic synthesis have been summarized by Kotha and co-workers. With a novel organophosphine ligand (SPhos), a catalyst loading of down to 0.001 mol% has been reported :