1-(苯甲酰氧基)-2,2,6,6-四甲基-4-哌啶酮

3-(甲氧羰基)-2,2,6,6-四甲基-4-氧代-

4-溴-1-氧基-2,2,5,5-四甲基-delta3-吡咯啉-3-羧酸

6-hydroxy-5,5,7,7-tetramethyl-1-oxa-6-azaspiro[2.5]octane