Section I: Synthesis of Optically Active 2-Sulfamyl- and Bicyclic 2-Sulfonyloxaziridines. Several optically active 3-aryl-2-sulfamyloxaziridines were prepared by biphasic peracid oxidation of the corresponding chiral sulfamylimines ${\rm (R\sb2 NSO\sb2 N}$ = CHAr). Oxidation of chiral sulfamylimines produces the sulfamyloxaziridines as a mixture of two diastereomers. A crystal structure was obtained for (+)-(R,R)-2-sulfamyl (N-(S)-$\alpha$-methylbenzyl-N-benzyl)-3-(3-nitrophenyl)oxaziridine, which confirmed the absolute configuration as (R,R) for the oxaziridine ring of this compound. It was found that (R,R) oxaziridines yield an excess of R-sulfoxides on oxidation of prochiral sulfides. The absolute configuration of other sulfamyloxaziridines was assigned based on correlations to the configuration of their sulfide oxidation products. The preparation of $\alpha$-chiral-organolithium compounds was examined in order to synthesize optically active 3-substituted-1,2-benzisothiazole-1,1-dioxides. Oxidation of these compounds with peracids in a biphasic system affords the corresponding bicyclic-2-sulfonyloxaziridines as a mixture of two diastereomers. Section 2: Asymmetric Oxidations of Sulfides. A series of aryl alkyl sulfides were oxidized using chiral oxaziridines. The results of these asymmetric oxidations were rationalized through the construction of a chiral recognition model. The results of these asymmetric oxidations were rationalized through the construction of a chiral recognition model. Since changes in both solvent polarity and substrate $\pi$-basicity produced negligible changes in enantioselectivity, it was concluded that $\pi$-acid-$\pi$-base complexation was not important to chiral recognition. The results were found to be more consistent with steric repulsion as the dominant force in selectivity. It was discovered that subtle changes in the substitution pattern of the 3-aryl group of the oxaziridine produced large changes in enantioselectivity. Those derivatives having aryl groups substituted on both sides of the ring (e.g. 2-Cl,5-${\rm NO\sb2,}$ 3,5-di-${\rm NO\sb2,}$ pentafluoro) were demonstrably superior in selectivity to those which were monosubstituted (e.g. 2-${\rm NO\sb2,3-NO\sb2,}$ 4-${\rm NO\sb2,}$ 2-Cl). It was concluded that a large 3-aryl group was favorable to selectivity. Enantiomeric excesses up to 90.6% were observed in some cases. Examination of Newman projections leads to the conclusion that a planar transition state geometry, in which the sulfide lone pair bisects the plane of the oxaziridine ring, is favored over a spiro geometry, where the sulfide lone pair shares the plane of the oxaziridine ring. (Abstract shortened with permission of author.)