Central nervous system activity of a novel class of annelated 1,4-benzodiazepines, aminomethylene-2,4-dihydro-1H-imidazo[1,2-a][1,4]benzodiazepin-1-ones.

The synthesis and CNS activity of a noval class of annelated 1,4-benzodiazepines, the aminomethylene-2,4-dihydro-1H-imidazo[1,2-a][1,4]benzodiazepines, are described. An investigation of the structure--activity relationships in the series derived from 8-chloro-2,4-dihydro-2-dimethylaminomethylene-6-phenyl-1H-imidazo[1,2-a][1,4]-benzodiazepin-1-one (10) led to the synthesis of a group of compounds with potent minor tranquillizer activity.