Three-membered rings, with two heteroatoms

Diaziridines, diazirines and dioxiranes are all relatively stable, isolable systems, although some dioxiranes are explosive. 

Three-membered rings with two heteroatoms are usually encountered only as reagents. Diazirines are nsefnl carbene precnrsors - they are generally more stable than the equivalent isomeric diazo compounds, thongh they are sometimes explosive in the pure state. They can be prepared by oxidation of diaziridines that, in tnm, are available via the condensation of a ketone or aldehyde with ammonia and chloramine. Chloro-diazirines, from the reaction of amidines with hypochlorite, wiU undergo Sn2 or Sn2 displacement reactions.  

Oxaziridines, prepared by the oxidation of imines, are selective oxygen-transfer reagents. In particular, the camphor-derived reagent is widely nsed for enantioselective oxygenation of enolates and other nucleophiles. 

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STRUCTURE OF THREE-MEMBERED RINGS WITH TWO HETEROATOMS... 

Although the three-membered rings with two heteroatoms were discovered only after 1950, they are accessible by very simple procedures familiar to the chemists decades before. The most common starting materials, peracids and N-haloamines, were available to the chemist before 1900 preparation, as well as isolation, follows standard procedures. 

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