Conformationally restricted butyrophenones with mixed dopaminergic (D2) and serotoninergic (5-HT(2A)) affinities. Synthesis of 5-aminoethyl-and 6- aminomethyl-4-oxotetrahydroindoles as potential atypical antipsychotics

Abstract

We describe the synthesis of 5-aminoethyl- and 6-aminomethyl-4- oxotetrahydroindoles as butyrophenone derivatives in the indole series, as potential atypical antipsychotics. The affinities of these compounds for serotonin (5-HT(2A)) and dopamine (D2) receptors were evaluated in vitro. The ratios of pK(i)'s for 5-HT(2A)/D2 receptors may be useful for rapid screening of new compounds and assessing potential induction of extrapyramidal symptoms; ratio values ≥1.12 (Meltzer's ratio) are predictive of an atypical antipsychotic profile. Compounds 26e (QF 0408B) and 26f (QF 0409B) showed high affinity for both D2 and 5-HT(2A) receptors, and their Meltzer's ratios were 1.32 and 1.17 respectively, while haloperidol showed a ratio of 0.93.