Synthesis and Structure−Activity Relationships of a New Model of Arylpiperazines. 3. 2-[ω-(4-Arylpiperazin-1-yl)alkyl]perhydropyrrolo- [1,2-c]imidazoles and -perhydroimidazo[1,5-a]pyridines: Study of the Influence of the Terminal Amide Fragment on 5-HT1A Affinity/Selectivity

A series of new arylpiperazine derivatives 2, which are devoid of the terminal amide fragment present in related 5-HT1A ligands, was prepared and evaluated for affinity at 5-HT1A and alpha 1 receptors. All the compounds 2 demonstrated high affinity for the 5-HT1A receptor and moderate affinity for alpha 1 receptor binding sites. Structure-activity relationship (SAR) studies suggest that there is influence of electronic factors on the no-pharmacophoric part of the alpha 1 receptor site. However there is no influence of electronic interactions on the stabilization of the 5-HT1A receptor-ligand complex.