Previous results of anticonvulsant activity in several imidooxy carboxylates related to (aminooxy)acetic acid in young chicks, prompted an in-depth reinvestigation of these analogues in mice. A series of 22 succinimidooxy, phthalimidooxy, and naphthalimidooxy carboxylates were synthesized and evaluated for anticonvulsant activity by the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS). Methyl (succinimidooxy)acetate (2d), ethyl (succinimidooxy)acetate (2e), methyl (phthalimidooxy)acetate (3d), ethyl (phthalimidooxy)acetate (3e), and ethyl 2-(phthalimidooxy)propionate (3g), which were initially found to be active as anticonvulsants in young chicks were uniformly inactive in the Phase I seizure tests involving maximal electroshock (MES), pentylenetetrazol (scMet), or neurologic toxicity toxicity (Tox). Several newer analogues, ethyl (succinimidooxy)formate (2c) and methyl 3-(phthalimidooxy)-2-methylacrylate (4h) were found to be active in the scMet (3a) or both (4h) evaluations. Most interesting was the anticonvulsant results of N-(benzyloxy)-2-azaspiro[4,4] nonane-1,3-dione (5b), which displayed anti-MES activity and a protective index (TD50/ED50) of greater than 4.5.