Synthesis, 5-HT1A and 5-HT2A receptor affinity of new 1-phenylpiperazinylpropyl derivatives of purine-2,6- and pyrrolidine-2,5-diones

Two series of 1-phenylpiperazinylpropyl derivatives 10, 11, 16, 17 and 19-24, structurally related to previously described 5-HT1A or 5-HT2A ligands 4 and 1, respectively, were synthesized and their binding properties were determined. Structural modifications which involved 1,3-diazepine ring opening in 4 (compounds 10, 11, 15, 16) and replacement of spiroalkyl moiety in 1 by aryl substituent (19-24) did not improve binding affinity and selectivity of the tested compounds. The results showed, however, that the diazepine ring present in 4 or spiroalkyl ring in 1 are important for high 5-HT1A or 5-HT2A binding affinity and selectivity of these compounds.