Suzuki reaction

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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.^[1]^[2] It is widely used to synthesize poly-olefins, styrenes, and substituted biphenyls, and has been extended to incorporate alkyl bromides [1]. Several reviews have been published.^[3]^[4]^[5]

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".

1 Reaction mechanism

1.1 Oxidative addition 1.2 Reductive elimination

[edit] 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^[6] with the boron-ate complex 6 forms the organopalladium species 8. Reductive elimination of the desired product 9 restores the original palladium catalyst 1.

[edit] Oxidative addition

Oxidative addition proceeds with retention of stereochemistry with vinyl halides, while giving inversion of stereochemistry with allylic and benzylic halides.^[7] The oxidative addition initially forms the cis-palladium complex, which rapidly isomerizes to the trans-complex.^[8]

[edit] Reductive elimination

Using deuterium-labelling, Ridgway et al. have shown the reductive elimination proceeds with retention of stereochemistry.^[9]

[edit] Scope

Recent applications of the Suzukiâ€“Miyaura cross-coupling reaction in organic synthesis has been summarized by Kotha and co-workers.^[10] With a novel organophosphine ligand (SPhos), a catalyst loading of down to 0.001 mol% has been reported ^[11]:

Suzuki Reaction Catalyst Loading Barder 2005

[edit] References

^ Miyaura, N. et al. Tetrahedron Lett. 1979, 3437. ^ Miyaura, N.; Suzuki, A. Chem. Commun. 1979, 866. ^ 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, 147â€“168. (Review) ^ Matos, K.; Soderquist, J. A. J. Org. Chem. 1998, 63, 461â€“470. (doi:10.1021/jo971681s) ^ Stille, J. K.; Lau, K. S. Y. Acc. Chem. Res. 1977, 10, 434â€“442. (doi:10.1021/ar50120a002) ^ Casado, A. L.; Espinet, P. Organometallics 1998, 17, 954â€“959. ^ Ridgway, B. H.; Woerpel, K. A. J. Org. Chem. 1998, 63, 458â€“460. (doi:10.1021/jo970803d) ^ Recent applications of the Suzukiâ€“Miyaura cross-coupling reaction in organic synthesis Sambasivarao Kotha, Kakali Lahiri and Dhurke Kashinath Tetrahedron 2002, 48, 9633-9695 doi:10.1016/S0040-4020(02)01188-2 ^ 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