An electron paramagnetic resonance study of the reaction of nitrosobenzene with cholesterol

The reaction of nitrosobenzene with cholesterol(Δ5-cholesten-3β-ol) producesa fairly stable aminoxyl (nitroxyl) derivative. This steroidal aminoxyl is presumed to be the oxidation product of the hydroxy lamine formed by Alder-ene addition of nitrosobenzene to cholesterol. Evidence is presented to show that, in this ene reaction, the double bond in the Δ5 position of the steroid shifts to the Δ4 rather than the Δ6 position.