Structure-activity relationships of tricyclic quinoxalinediones as potent antagonists for the glycine binding site of the NMDA receptor 2

Various modified compounds at the carbamoyl group of tricyclic quinoxalinedione 1b and at the position of bromine atom of 1a,b were synthesized and evaluated for their affinity for the glycine binding site of the NMDA receptor. Replacement of bromine atom of 1a,b with chlorine atom (14a,b) retained the activity.