The search for selective competitive antagonists at the NMDA-subtype of the excitatory amino acid (EAA) receptors has lead in the recent past to the synthesis of several compounds having therapeutic potential as antiexcitotoxins.'Among the new compounds so far introduced 2-carboxy-4-(3-phosphonopropyl) piperazine (CPP; 4) is one of the most frequently employed tools for biochemical and behavioral~ tudies.~-~ Very recently, a ...
