X-Ray structure and stereochemical properties of (S,S)-(–)-2-methylsulphonyl-3-phenyloxaziridine and of (S,S)-(–)-2-methylsulphonyl-3-(2-chloro-5-nitrophenyl)oxaziridine

Abstract

X-Ray analysis of crystalline, optically pure 2-methylsulphonyl-3-phenyloxaziridine (2a) and 2- methylsulphonyl-3-(2-chloro-5-nitrophenyl)oxaziridine (2b), obtained by asymmetric oxidation of the corresponding prochiral N-benzlidenemethylsulphonylimine (1a) and N-(2-chloro-5-nitrobenzylidene)methylsulphonylimine (1b) with (1S)-(+)-peroxycamphoric acid, (+)-PCA, followed by fractional crystallization of the crude products, shows that the absolute configuration at the chiral nitrogen and carbon atoms of the oxaziridine rings of both (–)-(2a) and (–)-(2b) derivatives is (S,S). C.d. spectra of (–)-(2a) and (–)-(2b) indicate that the chiroptical properties of these compounds can be correlated with the observed (S,S) configuration. On the other hand, asymmetric oxidations of prochiral sulphides and olefins, carried out with both (–)-(2a) and (–)-(2b) as chiral oxidizing reagents, indicate that the stereochemical properties of these oxaziridine derivatives are dependent on the substituted or unsubstituted structure of the phenyl group directly linked to the carbon atom of the three-membered ring.