Synthesis and binding properties of new long-chain 4-substituted piperazine derivatives as 5-HT1A and 5-HT7 receptor ligands

New long-chain 4-substituted piperazines linked to a thienopyrimidine or a quinazoline system weresynthesized and tested for their binding properties on human cloned 5-HT1Aand 5-HT7serotonin receptors. Some structural modifications, concerning tree main portions, that is, terminal fragment, chainlength, and aryl substituents, were examined. The 2- and 3-substituted thienopyrimidinone and quinazolinone systems were selected as terminal fragment and a chain length of four or five methylene unitswas set. Explored aryl substituents were phenyl, phenylmethyl, 3- or 4-chlorophenyl, and 2-ethoxyphenyl. Title compounds showed affinity for 5-HT1A and 5-HT7 receptors. In particular, 2-ethoxyphenylderivatives40and45displayedKivalues in the nanomolar range on both receptors, acting as dual ligands.