Davis oxidation explained

In organic chemistry, the Davis oxidation or Davis' oxaziridine oxidation refers to oxidations involving the use of the Davis reagent (2-(phenylsulfonyl)-3-phenyloxaziridine) or other similar oxaziridine reagents.^[1] This reaction mainly refers to the generation of α-hydroxy carbonyl compounds (acyloins) from ketones or esters.^{[2] [3]} The reaction is carried out in a basic environment to generate the corresponding enolate from the ketone or ester. This reaction has been shown to work for amides.^[4]

Other oxidations carried out by Davis' reagent include the oxidation of sulfides and selenides to sulfoxides^{[5] [6]} and selenoxides^[7] without further oxidation; the oxidation of alkenes to epoxides;^{[8] [9] [10]} and the oxidation of amines to hydroxylamines and amine oxides.^[11]

Mechanism

Regarding the α-hydroxylation of carbonyls, the base first converts the ketone or ester into its corresponding enolate. Then, the enolate anion as a nucleophile attacks the oxygen atom of the oxaziridine in a S_N2 mechanism, forming a hemiaminal intermediate. The intermediate then fragments into a sulfinimine, and, after protonation, the desired α-hydroxyketone or α-hydroxyester.^{[12] [13]}

See also

• Rubottom oxidation - also produces α-hydroxy carbonyl compounds

Notes and References

1. Book: Kürti . László . Czakó . Barbara . Strategic Applications of Named Reactions in Organic Synthesis . 29 September 2005 . 978-0-12-429785-2 . 130–131.
2. Davis. Franklin A.. Franklin A. Davis. Vishwakarma . Lal C.. Billmers. Joanne G.. Finn. John. 1 August 1984. Synthesis of α-hydroxycarbonyl compounds (acyloins): direct oxidation of enolates using 2-sulfonyloxaziridines. The Journal of Organic Chemistry. 49. 17. 3241–3243. 10.1021/jo00191a048.
3. Davis . Franklin A. . Chen . Bang Chi . Franklin A. Davis . Asymmetric hydroxylation of enolates with N-sulfonyloxaziridines . Chemical Reviews . 1992 . 92 . 5 . 919–934 . 10.1021/cr00013a008.
4. Evans . David Albert . Morrissey . Michael M. . Dorow . Roberta L. . David A. Evans . Asymmetric oxygenation of chiral imide enolates. A general approach to the synthesis of enantiomerically pure α-hydroxy carboxylic acid synthons . Journal of the American Chemical Society . 1985-07-01 . 107 . 14 . 4346–4348 . 10.1021/ja00300a054.
5. Mata . Ernesto G. . Recent advances in the synthesis of sulfoxides from sulfides . Phosphorus, Sulfur, and Silicon and the Related Elements . 1996 . 117 . 1 . 231–286 . 10.1080/10426509608038790.
6. Bohé . Luis . Lusinchi . Marie . Lusinchi . Xavier . Oxygen atom transfer from a chiral N-alkyl oxaziridine promoted by acid. The asymmetric oxidation of sulfides to sulfoxides . Tetrahedron . 1999 . 55 . 1 . 155–156 . 10.1016/S0040-4020(98)01035-7.
7. Davis . Franklin A. . Stringer . Orum D. . Billmers . Joanne M. . Franklin A. Davis . Oxidation of selenides to selenoxides using 2-sulfonyloxaziridines . . 1983 . 24 . 12 . 1213–1216 . 10.1016/S0040-4039(00)81617-2.
8. Davis . Franklin A. . Abdul-Malik . Nadia F. . Awad . Sami B. . Harakal . Mark E. . Franklin A. Davis . Epoxidation of olefins by oxaziridines . . 1981 . 22 . 10 . 917–920 . 10.1016/0040-4039(81)89008-9.
9. Davis . Franklin A. . Harakal . Mark E. . Awad . Sami B. . Chemistry of oxaziridines. 4. Asymmetric epoxidation of unfunctionalized alkenes using chiral 2-sulfonyloxaziridines: evidence for a planar transition state geometry . . 1983 . 105 . 10 . 3123–3126 . 10.1021/ja00348a029.
10. Bohé . Luis . Lusinchi . Marie . Lusinchi . Xavier . Oxygen atom transfer from a chiral oxaziridinium salt. Asymmetric epoxidation of unfunctionalized olefins . Tetrahedron . 1999 . 55 . 1 . 141–154 . 10.1016/S0040-4020(98)01034-5.
11. Zajac . Walter W. Jr. . Walters . Thomas R. . Darcy . Michael G. . Oxidation of amines with 2-sulfonyloxaziridines (Davis' reagents) . . 1988 . 53 . 25 . 5856–5860 . 10.1021/jo00260a012.
12. Davis . Franklin A. . Sheppard . Aurelia C. . Chen . Bang Chi . Haque . M. Serajul . Franklin A. Davis . Chemistry of oxaziridines. 14. Asymmetric oxidation of ketone enolates using enantiomerically pure (camphorylsulfonyl)oxaziridine . . 1990 . 112 . 18 . 6679–6690 . 10.1021/ja00174a035.
13. Davis . Franklin A. . Weismiller . Michael C. . Murphy . Christopher K. . Reddy . R. Thimma . Chen . Bang Chi . Franklin A. Davis . Chemistry of oxaziridines. 18. Synthesis and enantioselective oxidations of the [(8,8-dihalocamphoryl)sulfonyl]oxaziridines . . 1992 . 57 . 26 . 7274–7285 . 10.1021/jo00052a050.