fig2: Asynchronoustransition state for oxygen atom transfer reactionsof N-sulfonyloxaziridines.

Mentions: At elevatedtemperatures, Davis’ oxaziridines can be utilized to synthesizeepoxides from alkenes.64 Experimentally,the transition state for the transfer of oxygen from N-sulfonyloxaziridines to alkenes has been investigated using theendocyclic restriction test.65 By evaluatinga number of substrates containing an oxaziridine and an alkene, Beakand co-workers concluded that the transition state of oxygen transferfrom an N-sulfonyloxaziridine to a correspondingnucleophile is one in which N–O bond cleavage is more advancedthan C–O bond cleavage (Figure 2, 47). Houk et al. also performed computational studies thatprobe the transfer of oxygen from oxaziridines to alkenes. These calculationssimilarly indicate a concerted, asynchronous process; advanced cleavageof the N–O bond is accompanied by significant buildup of partialnegative charge at nitrogen.66 Thus, toa first approximation, oxaziridines can be considered electrophilicoxidants, and factors that stabilize the incipient negative chargeat nitrogen are expected to increase the reactivity of oxaziridines.