Synthesis, Pharmacophore Modeling, and Biological Evaluation of Novel 5H-Thiazolo[3,2-a]pyrimidin-5-one Derivatives as 5-HT_2A Receptor Antagonists

Novel 5H-thiazolo[3,2-a]pyrimidin-5-one derivatives linked through an ethylene bridge to various phenylpiperazine groups were prepared for evaluation as 5-HT_2A receptor antagonists. The target compounds 11a–p were prepared through the initial synthesis of the 2-chloroethyl intermediates 10a–d which were then reacted with the appropriate phenylpiperazines. All compounds were tested for their antagonistic activity on 5-HT_2Areceptors using inhibition of 5-hydroxytryptophan(5-HTP)-induced head twitches in mice. Pharmacophore modeling study, based on a hypothetical pharmacophore template generated from a set of diverse known active ligands, revealed good fitting of the designed compounds to the generated hypothetical pharmacophore.