Baeyer-Villiger oxidation



The Baeyer-Villiger oxidation is an Johann Friedrich Wilhelm Adolf von Baeyer (1835-1917) and the Swiss chemist Victor Villiger (1868-1934).

Reagents typically used to carry out this rearrangement are transesterification.

Mechanism

The carboxylic acid. For unsymmetrical ketones, the migrating group is the one that gives the most stable cation. If the migrating carbon is chiral, the stereochemistry is retained.

Cation stability: H > tertiary alkyl > cyclohexyl > secondary alkyl, aryl > primary alkyl > methyl

In the antibonding O-O sigma bond. This step is also (at least in silico) assisted by two or three peroxyacid units enabling the hydroxyl proton to shuttle to its new position[6].

Thus, cyclic ketones produce carboxylic acids although sometimes a alcohol is formed when the formate is hydrolytically unstable.

Biocatalytic BV oxidation

The Baeyer-Villiger oxidation can also be performed by NADPH and the costs associated with BVMO's themselves because lengthy purification steps are required. In vivo oxidations with metabolically active microbial cells introduce complications on their own.

In one study [7] the enzyme purification issue is addressed and a special thermally stable monooxygenase is isolated from a specific E-coli strain. This isopropanol as a sacrificial catalyst. The solubility of the organic reactant and product is low in the aqueous phase thus averting asymmetric catalysts.

References

  1. ^ Ber. 32 (3): 3625–3633. doi:10.1002/cber.189903203151.
  2. ^ Ber. 33 (1): 858–864. doi:10.1002/cber.190003301153.
  3. ^ Crudden, C. M.; Chen, A. C.; Calhoun, L. A. (2000). "A Demonstration of the Primary Stereoelectronic Effect in the Baeyer-Villiger Oxidation of α-Fluorocyclohexanones". Angew. Chem. Int. Ed. 39 (16): 2851–2855. doi:10.1002/1521-3773(20000818)39:16<2851::AID-ANIE2851>.0.CO;2-Y.
  4. ^ Burton, J.W.; Clark, J.S.; Derrer, S.; Stork, T.C.; Bendall, J.G.; Holmes, A.B. (1997). "Synthesis of Medium Ring Ethers. 5. The Synthesis of (+)-Laurencin" (Abstract). J. Am. Chem. Soc. 119 (32): 7483–7498. doi:10.1021/ja9709132.
  5. ^ Michael Renz, Bernard Meunier (1999). "100 Years of Baeyer-Villiger Oxidations". European Journal of Organic Chemistry 1999 (4): 737 - 750. doi:<737::AID-EJOC737>3.0.CO;2-B 10.1002/(SICI)1099-0690(199904)1999:4<737::AID-EJOC737>3.0.CO;2-B.
  6. ^ a b The Role of Hydrogen Bonds in Baeyer-Villiger Reactions Shinichi Yamabe and Shoko Yamazaki J. Org. Chem.; 2007; 72(8) pp 3031 - 3041; (Article) doi:10.1021/jo0626562
  7. ^ Frank Schulz; François Leca; Frank Hollmann; Manfred T Reetz (2005). "Towards practical biocatalytic Baeyer-Villiger reactions: applying a thermostable enzyme in the gram-scale synthesis of optically active lactones in a two-liquid-phase system" (PDF). Beilstein Journal of Organic Chemistry 1 (10). doi:10.1186/1860-5397-1-10.

See also

  • Dakin reaction
 
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