4, 4-Dimethyloxazolidine-N-oxyls (doxyls), the very useful nitroxide spin labels, can be reconverted rapidly and efficiently to their parent ketones with nitrogen dioxide (conveniently as contained in commercial nitric oxide) in. ethanol at room temperature. This reaction is interpreted as involving initial oxidation to give an oxoammonium salt, eg, 5 from 1, followed by fragmentation to an oxonium ion, eg, 6, and cleavage to ketone. The mass spectra of ...
