4-Carboxy-2,2,6,6-tetramethylpiperidine1-oxyl
4-Oxo-tempo
3-Carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy
2-Azaadamantane-N-oxyl
2,2,6,6-Tetramethyl-4-(2-propynyloxy)piperidine 1-oxyl
