Stereochemical and mechanistic aspects of the base-catalysed decomposition of N-alkyloxaziridines to form NH ketimines

The synthesis of a new range of oxaziridines (18)–(23), (30)–(35) by peracid oxidation of diaryl ketimines and aryl aldimines is reported. Relatively stable NH ketimine products (24)–(27) have been isolated from base-catalysed decomposition of the oxaziridines (18)–(20), (30)–(35) and a primary kinetic isotope effect (ca. kH/kD 6.0) was observed during decomposition of the oxaziridine trans-(31). The trans-oxaziridines (31)–(35) were found to decompose at a faster rate than the corresponding cis isomers. The relative rates of base-catalysed decomposition of oxaziridine stereoisomers are consistent with a mechanism involving an α-C–H proton abstraction mechanism.