Enolates camphorylsulfonyl oxaziridine

ASYMMETRIC OXIDATION OF LITHIUM ENOLATES OF ESTERS AND AMIDES USING (+)-(2R.8aS)-10-(CAMPHORYLSULFONYL)OXAZIRIDINE... 

Chiral Davis oxaziridines allow the oxidation of phosphonates to a-hydroxy-phosphonates in good ee with apparently wide generality and with a sense of induction that is well controlled by the chirality of the reagent used.109 mCPBA oxidation of a bi-cyclic e do-camphorylsulfonylimine surprisingly resulted in an exo-camphorylsulfonyl-oxaziridine, whereas all other camphorylsulfonylimines resulted only in endo-oxaziiidines.110 Asymmetric oxidation of sulfides to sulfoxides and the a-hydroxylation of enolates were predicted by models in which steric interactions are minimized. 

ASYMMETRIC HYDROXYLATION OF TETRALONE AND PROPIOPHENONE ENOLATES USING (CAMPHORYLSULFONYL)OXAZIRIDINES 1 AND 2... 

Davis, F. A., Sheppard, A. C., Chen, B. C., Hague, M. S. Chemistry of oxaziridines. 14. Asymmetric oxidation of ketone enolates using enantiomerically pure (camphorylsulfonyl)oxaziridine. J. Am. Chem. Soc. 1990,112, 6679-6690. 

Acyclic a-hydroxy ketones of high enantiomeric purity can be prepared by choice of the appropriate conditions and (camphorylsulfonyl)oxaziridine reagent, for example, treatment of deoxy-benzoin (159a) with NaHMDS followed by (+)-(114) at —78°C affords (+ )-(S)-benzoin (160) in 95% ee and 88% isolated yield (Scheme 29) <89JOC202i, 90JA6679). Similarly, (—)-(S)-2-hydroxy-1 -phenyl-1-propanone (161) is produced in 95% ee by hydroxylation of the lithium enolate of... 

Asymmetric hydroxylation of enolates. Davis and Chen have reviewed this reaction using in particular (R,R)- and (S,S)-2-phenylsulfonyl)-3-phenyloxaziridene (1) and (camphorylsulfonyl)oxaziridine (2). Of these reagents, 1 and (+)- and (—)-2, derived from (IR)-lO-camphorsulfonic acid, provide highest enantioselectivity and in addition are easy to prepare. They are effective for hydroxylatation of ketones, esters, -keto esters, amides, lactones, and lactams. 

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