Synthesis of spin-labeled nitroxyl esters of steroids

The preparations of spin-labeled nitroxyl esters of prednisone, cortisone, deoxycorticosterone, and cholesterol are described. The ESR spectra indicate that the esters of the three steroids with an oxygen atom at the 11 position have narrower band widths than those with only protons at that position. Mass spectral, chemical, and ESR studies confirmed the structures and purity of the compounds prepared. Reaction of four esters with prednisone antibodies showed reversible binding and large crossover binding.