Oxaziridine reactions deoxygenation

The unstable dibenz[c,/][l,2]oxazepines (312 R = CN, Cl) have been isolated as the major products of the UV irradiation of 9-cyano- and 9-chloro-acridine 10-oxides (310) in benzene (c/. the analogous Af-imide to 1,2-diazepine conversion on p. 598). Although none of the oxaziridine tautomer (311) was detectable by UV spectroscopy, the subsequent deoxygenation of (312) to acridine suggests the existence of a thermal equilibrium between (311) and (312) (79T1273). These dibenzo compounds (312) are the only fully unsaturated oxazepines yet isolated but the 2,3-benzoxazepin-l-one system (314) has recently been prepared by the reaction of benzonitrile oxide with the benzopyranone (313) (80JCS(Pl)846). 

However, more complex sulfur nucleophiles, such as thiourea, thiocyanate ion, and xanthate salts appeared to accomplish deoxygenation of the oxaziridines by ring-opening attack at carbon followed by the usual reactions leading to thia-ziridines, which lost elemental sulfur." ... 

In the following years, studies conducted by Sharpless,6 7 Bach,8,9 Curci,10 and others11 relied on reaction kinetics to formulate support of a SN2-type displacement by the nucleophilic substrate on the electrophilic oxygen atom of the three-membered ring. Similarly, the deoxygenation of oxaziridines, such as 1, is kinetically consistent with the aforementioned Sn2 mechanism. 

---