Abstract
A new series of 2-alkoxy-4-amino-5-chlorobenzamide derivatives bearing five- to seven-membered heteroalicyclic rings in the amine moiety was synthesized and evaluated for serotonin-3 (5-HT3) receptor antagonistic activity by assaying the ability to antagonize the von Bezold-Jarisch reflex in rats. The five- to seven-membered heteroalicycles comprise pyrrolidine, morpholine, 1, 4-thiazine, piperidine, piperazine, 1, 4-oxazepine, 1, 4-thiazepine, azepine, and 1, 4-diazepine rings. Among them, some benzamide derivatives having a 1, 4-diazepine ring showed a potent 5-HT3 receptor antagonistic activity. In particular, 4-amino-5-chloro-N-(1, 4-dimethylhexahydro-1H-1, 4-diazepin-6-yl)-2-ethoxybenzamide (96) and the 1-benzyl-4-methylhexahydro-1H-1, 4-diazepine analogue 103 showed potent 5-HT3 receptor antagonistic activity without 5-HT4 receptor binding affinity.
