A novel class of potential central nervous system agents. 3-Phenyl-2-(1-piperazinyl)-5H-1-benzazepines

A series of 3-phenyl-2-piperazinyl-5H-1-benzazepines and related compounds were synthesized and evaluated for potential neuroleptic activity. The preparation of these compounds was carried out by 2,3-dichlorination of 3-phenyl-2,3,4,5-tetrahydro-1H-1-benzazepin-2-ones with phosphorus pentachloride followed by amination and concurrent dehydrochlorination. Compounds having the 4-chloro or 4-fluoro substituent in the 3-phenyl group were found to possess the neuroleptic-like activity. Among them, 2-(4-methyl-1-piperazinyl)-3-(4-fluorophenyl)-5H-1-benzazepine dihydrochloride (23) was comparable to chlorpromazine in inhibiting exploratory activity, conditioned avoidance response, and self-stimulation response and more potent than chlorpromazine in antagonizing apomorphine-induced emesis. These neuroleptic effects may be based on an antidopaminergic property of the compound. In causing catalepsy or ptosis, however, 23 was weaker than chlorpromazine. Therefore, this ring system is of interest as a novel class of neuroleptics. Some compounds having the 7-chloro or 7-bromo substituent showed potent anticonvulsant effects against maximal seizures induced by electroshock or pentylenetetrazole.