Oxaziranes reduction

A second group of oxazirane reductions is characterized by transfer of the ring oxygen atom to an oxidizable substrate. Thus... 

Further indications of the structure of the oxaziranes are obtained by reduction and isomerization. None of the reactions described in the following sections is incompatible with the three-membered ring structure. 

Some oxaziranes can be prepared very simply from ketones and N-chloroamines. Thus 2-methyl-3,3-pentamethyleneoxazirane is easily obtained from cyclohexanone and iV-methylchloramine its reduction by ferrous salts gives an alkyl radical, which has been used to alkylate, in high yield, protonated heteroaromatic bases in aqueous solution (Scheme 5). 

Oxaziranes are active oxygen compounds and react with a wick variety of reducing agents- The meet important of these is the reaction with potassium iodide since this reaction is the basis of the iodimetric procedure for assay of oxazirane purity. The reaction has also been examined preparatively and forms a basis for reduction of oxaziranrs... 

The a-hydroxy-nitrone (72) is isomerised (toluene-p-sulphonic acid-benzene) to (81). Reduction of (81) with NaBH4 gives the hydroxylamine (83). Incomplete reduction leads to the nitrone (82). Oxidation of (83) with Cu gives the isomeric nitrone (84). The photochemistry of the nitrones (82) and (84) as well as that of the steroidal oxazirans has been studied. Nitrone (82) gives the two oxazirans (85) and (86), while (84) gives a mixture of the oxazirans (87). Irradiation of the oxazirans (87) leads to an azetidine (88, R = Ac). 

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