Synthesis of imidazolidinediones and oxazolidinediones from cyclization of propargylureas and propargyl carbamates.

A synthetic procedure for the preparation of imidazolidinediones by the base-catalyzed cyclization of propargylureas is described. This method appears to be the most versatile way of obtaining these compounds containing tertiary groups substituted on ring-nitrogen number 3. One of these derivatives, 3-tert-butyl-5,5-dimethyl-2,4-imidazolidinedione (1a), has shown a moderate level of subcutaneous metrazole seizure threshold activity (scMet indicates potential for control of petit mal epileptic seizures) in control screens on mice, as determined by the National Institute of Neurological and Communicative Disorders and Stroke.