The use of 2-(phenylsulfonyl)-3-phenyloxaziridine (Davis reagent) or similar oxaziridine reagents enables an oxidation of enolates generated in situ from ketones or esters to provide α-hydroxylated compounds.
Mechanism of the Davis Oxidation
The transfer of oxygen from N-sulfonyloxaziridines to nucleophiles happens in a SN2 mechanism, in which the enolate anion as nucleophile attacks the oxaziridine oxygen atom to give a hemiaminal intermediate.
This hemiaminal intermediate fragments to a sulfinimine and the desired α-hydroxy ketone.
Synthesis of α-hydroxycarbonyl compounds (acyloins): direct oxidation of enolates using 2-sulfonyloxaziridines
F. A. Davis, L. C. Vishwakarma, J. G. Billmers, J. Finn, J. Org. Chem., 1984, 49, 3241-3243.
Chemistry of oxaziridines. 14. Asymmetric oxidation of ketone enolates using enantiomerically pure (camphorylsulfonyl)oxaziridine
F. A. Davis, A. C. Sheppard, B. C. Chen, M. S. Haque, J. Am. Chem. Soc., 1990, 112, 6679-6690.