The Bayer-Villiger oxidation is a useful method for conversion of aldehydes and ketones to esters by the insertion of an oxygen atom from a peroxycarboxylic acid (RCO3H). For example, treating acetophenone with a peroxycarboxylic acid converts it to the ester phenyl acetate.
MechanismBack to Top
The Baeyer-Villiger oxidation is also widely used for synthesizing lactones from cyclic ketones. A common reagent used to carry out the Baeyer-Villiger oxidation is m-chloroperoxybenzoic acid. Certain other peroxycarboxylic acids can be used as well and we will discuss shortly a "green" variation of the Baeyer-Villiger oxidation by a peroxycarboxylic acid.
The following is a mechanism proposed for Baeyer-Villiger oxidation by a peroxycarboxylic acid.
Baeyer-Villiger MonooxygenaseBack to Top
Asymmetric oxidations play an important role in organic synthesis. Many valuable highly efficient chemocatalytic methods have been developed. Besides chemocatalysts, enzymes turned out to present useful catalysts. Notably a broad range of different types of oxidation reactions can be catalyzed by bio catalysts.
To start with the oxidation of a carbon atom, one can convert a ketone moiety into an ester in an asymmetric fashion by means of a so called Baeyer-Villiger monooxygenase.
ExamplesBack to Top
Baeyer-Villiger oxidation of a Mannich base having an appropriate substituent for selective migration on to the oxo carbonyl group opens a valuable possibility for the synthesis of $\beta$-amino esters and acids. Examples are the synthesis of epi-cytoxazone and the $\alpha$-hydroxy-$\beta$-amino acid derivatives from ketones respectively.
ApplicationBack to Top
- The Baeyer-Villiger reaction is widely appreciated in organic synthesis as it is applicable to a broad range of carbonylic compounds while the moiety that will migrate during the reaction can also be predicted to some extent.
- An additional attractive feature of the Baeyer-Villiger reaction is that the migrating group will typically retain its configuaration. This allows effective and selective oxidation reactions. However, a major drawback of the reaction is the intrinsic need for a potent and therefore hazardous oxidising agent.
- The classical approach to perform a Baeyer-Villiger reaction includes the use of organic peroxyacids as catalyst. In addition to the fact that these reactive compounds have to be handled with care, they are also relatively expensive.