1,3-Diazaspiro(4.4)nonane-2,4-dione 5,5'-Cyclopentanespirohydantoin 5,5-Tetramethylenehydantoin 5,5-Tetramethylenespirohydantoin 5-24-07-00271 (Beilstein Handbook Reference) 699-51-4 BRN 0135190 Ba 2839 CB 1683