The Baeyer-Villiger oxidation reaction uses an oxidizing agent such as peroxyacid to convert ketones or cyclic ketones to esters and lactones/ hydroxy acid respectively. Peroxyacid first attacks a protonated carbonyl group, forming a tetrahedral intermediate named the Criegee intermediate. An alkyl migration and loss of carboxylic acid then takes place in a concerted process, followed by deprotonation to form the ester.
- Reagents: Peroxyacid, CH2Cl2
- Reactant: Ketone
- Product: Ester
- Type of Reaction: Oxidation
Lab Tips
- Oxidation with peroxyacid tolerates many functional groups, e.g. the double bond in α,β-unsaturated ketones is not oxidized. [1]
- Multiple oxidizing agents can be used: CF3CO3H > monopermaleic acid > monoperphthalic acid > 3,5-dinitroperbenzoic acid > p-nitroperbenzoic acid > mCPBA and performic acid > perbenzoic acid > peracetic acid >> H2O2 > t-BuOOH. [2]
- Regiochemistry is dependent on the migratory aptitude of different alkyl groups. For acyclic symmetrical ketones, the migrating group must be 2°, 3° or vinylic. For unsymmetrical ketones, the (approximate) order of migration is 3° alkyl > 2° alkyl > aryl > 1° alkyl > methyl. In bicyclic systems, various stereoelectronic aspects can influence which group migrates.
- Retention of stereochemistry occurs at the migrating center during the rearrangement step. [1]
- Promising catalysts include substituted seleninic acids that can be generated in situ from diaryl diselenides with H2O2 (called the Syper method of activation). [2,3]
2. ten-Brink, G.-J., Vis, J.-M., Arends, I. W. C. E., Sheldon, R. A. Selenium-catalyzed oxidations with aqueous hydrogen peroxide. 2. Baeyer-Villiger reactions in homogeneous solution. J. Org. Chem. 2001, 66, 2429-2433.
3. Syper, L. The Baeyer-Villiger oxidation of aromatic aldehydes and ketones with hydrogen peroxide catalyzed by selenium compounds. A convenient method for the preparation of phenols. Synthesis 1989, 167-172.
Mechanism
Top Citations
Original Paper
Related Reactions
- Dakin-West Reaction
Related Compounds
- Hydrogen peroxide (CAS 7722-84-1)
- m-chloroperoxy benzoic acid (CAS 937-14-4)
