Design and synthesis of new homo and hetero bis-piperazinyl-1-propanone derivatives as 5-HT₇R selective ligands over 5-HT_1AR

In this work we report the discovery of new homo and hetero bis-piperazinyl-1-propanone derivatives as selective ligands for 5-HT₇ over 5-HT_1A receptor. These newly synthesized compounds possess a 4-arylpiperazine linked through an acyl spacer to another substituted piperazine system and were tested for their binding properties on human cloned 5-HT_1A and 5-HT₇ serotonin receptors. Among these, phenyl, 4- and 2-chlorophenyl, 2-methoxyphenyl, 2-pyridyl, and 2-pyrimidyl derivatives 15, 24, 25, and 27–29 displayed nanomolar affinity values for the 5-HT₇ receptor (K_i 23.5–52.0 nM) and no affinity for the 5-HT_1A receptor.