Sulfenimines, asymmetric oxidations, sulfinimines

Another approach to the enantiomerically enriched sulfinimines reported by Davis and co-workers is the enantioselective oxidation of sulfenimines with an asymmetric oxidizing reagent, (-)-jV-(phenylsulfonyl)(3,3-dichlorocamphoryl)-... 

N-Sulfonyloxaziridines are an important class of selective, neutral, and aprotic oxidizing reagents.11 Enantiopure N-sulfonyloxaziridines have been used in the asymmetric hydroxylation of enolates to enantiomerically enriched a-hydroxy carbonyl compounds,9 11-13 the asymmetric oxidation of sulfides to sulfoxides,14 1S selenides to selenoxides,16 sulfenimines to sulfinimines,17 and the epoxidation of alkenes.18... 

Sulfenimines undergo asymmetric oxidations to form sulfinimines via a reaction with Davis reagents. The sulfenimine 77 was oxidized by 9 to yield the sulfmimine 78 in 82% yield and 97% ee. Yields and enantiomeric excess varied based on the oxaziridine reagent used.64... 

Enantiopure sulfinimines are ammonia imine synthons useful in the asymmetric synthesis of amines and -amino acid derivatives. Sulfinimines unavailable via the Andersen synthesis (R = H) are prepared hy asymmetric oxidation of the sulfenimines, ArS-N=C(R)PhX, with (+)-( ) or (-)-(1) at -20 to 20 °C in CCI4 (eq 8). Crystallization improves the ee to >95%. The sulfoxide chiral recognition model correctly predicts the configuration of the product. 

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