Synthesis and Dual D<sub>2</sub> and 5-HT<sub>1A</sub> Receptor Binding Affinities of 7-piperazinyl and 7-piperidinyl-3,4-dihydroquinazolin-2(1H)-ones

A series of new 7-piperazinyl and 7-piperidinyl-3,4-dihydroquinazolin-2(1H)-ones has been synthesized. The described compounds are structurally related to adoprazine, a potential atypical antipsychotic bearing potent D2 receptor antagonist and 5-HT1A receptor agonist properties. Suitably modified aryl bromides were prepared and condensed with tert-butyl piperazine-1-carboxylate to afford the advanced intermediate piperazinyl-3,4-dihydroquinazolin-2(1H)-one. Likewise Suzuki-Miyaura cross-coupling reaction of cyclic vinyl boronate with appropriate aryl bromides rendered piperidinyl-3,4-dihydroquinazolin-2(1H)-one. The reductive amination of the piperazinyl and piperidinyl-3,4- dihydroquinazolin-2(1H)-ones with suitably designed biarylaldehydes accomplished the synthesis of these title compounds. The described compounds were screened for D2 and 5-HT1A receptors binding affinities. The structure-activity relationship studies revealed that cyclopentenylpyridine and cyclopentenylbenzyl groups contribute significantly to the dual D2 and 5-HT1A receptor binding affinities of these compounds.