Suzuki reaction

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. [Miyaura, N. "et al." "Tetrahedron Lett." 1979, 3437.] [Miyaura, N.; Suzuki, A. "Chem. Commun." 1979, 866.] It is widely used to synthesize poly-olefins, styrenes, and substituted biphenyls, and has been extended to incorporate alkyl bromides [http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/2002/124/i46/abs/ja0283899.html] . Several reviews have been published. [Suzuki, A. "Pure Appl. Chem." 1991, "63", 419-422. (Review)] [Miyaura, N.; Suzuki, A. "Chem. Rev." 1995, "95", 2457-2483. (Review, DOI|10.1021/cr00039a007)] [Suzuki, A. "J. Organometallic Chem." 1999, "576", 147–168. (Review)]

The reaction also works with pseudohalides, such as triflates (OTf), instead of halides, and also with boron-esters 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.

In many publications this reaction also goes by the name Miyaura-Suzuki 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 organo-palladium species 3. Reaction with base gives intermediate 4, which via transmetalation [Matos, K.; Soderquist, J. A. "J. Org. Chem." 1998, "63", 461–470. (DOI|10.1021/jo971681s)] 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. [Stille, J. K.; Lau, K. S. Y. "Acc. Chem. Res." 1977, "10", 434–442. (DOI|10.1021/ar50120a002)] The oxidative addition initially forms the cis-palladium complex, which rapidly isomerizes to the trans-complex. [Casado, A. L.; Espinet, P. "Organometallics" 1998, "17", 954–959.]

Reductive elimination

Using deuterium-labelling, Ridgway "et al." have shown the reductive elimination proceeds with retention of stereochemistry. [Ridgway, B. H.; Woerpel, K. A. "J. Org. Chem." 1998, "63", 458–460. (DOI|10.1021/jo970803d)]

cope

With a novel organophosphine ligand (SPhos), a catalyst loading of down to 0.001 mol% has been reported ["Catalysts for Suzuki-Miyaura Coupling Processes: Scope and Studies of the Effect of Ligand Structure" Timothy E. Barder, Shawn D. Walker, Joseph R. Martinelli, and Stephen L. Buchwald J. AM. CHEM. SOC. 2005, 127, 4685-4696 DOI|10.1021/ja042491j] :

ee also

* Heck reaction
* Hiyama coupling
* Kumada coupling
* Negishi coupling
* Petasis reaction
* Stille reaction
* Sonogashira coupling

References

External links

* [http://www.organic-chemistry.org/namedreactions/suzuki-coupling.shtm Suzuki coupling]