Synthesis of 5,6-dihydro-4H-imidazo[1,5-a][4,1]benzoxazepin-6-ones and their transformation into 5,6-dihydro-4H-imidazo[1,5-a][1,4]benzodiazepin-6-ones

Novel 5,6-dihydro-4H-imidazo[1,5-a][4,1]benzoxazepin-6-ones have been prepared from benzoxazepindiones by 1,3-dipolar cycloadditions. Ring opening of the oxygen analogues with amines, chlorination followed by base promoted recyclisation provided 5,6-dihydro-4H-imidazo[1,5-a][1,4] benzodiazepin-6-ones by a novel route.