1-Benzoyl-4-bromo-1,2,3,4-tetrahydro-benzo[b]azepin-5-one (67.5 g, 200 mmol) from Example E5.7, acetamidine hydrochloride (92.7 g, 980 mmol) and potassium carbonate (136.0 g, 980 mmol) were suspended in acetonitrile (2.0 liters) and heated at reflux for 17 h under nitrogen. Additional acetamidine hydrochloride (18.5 g, 200 mmol) and potassium carbonate (27.7 g, 200 mmol) were added and the reaction mixture was heated at reflux for a further 6 h. Additional acetamidine hydrochloride (18.5 g, 200 mmol) and potassium carbonate (27.7 g, 200 mmol) were added again and the reaction mixture was heated at reflux for a further 6 h. On cooling to room temperature, the reaction mixture was filtered and the filtrate was concentrated in vacuo. The residue was taken up in dichloromethane (1.4 liters), washed with water (500 ml), dried over sodium sulfate, filtered and reduced in vacuo. The crude products were purified by flash chromatography on silica gel (eluant; 45% EtOAc:45% acetonitrile: 10% methanol) to yield the title compound (26.7 g, 34%) and 6-benzoyl-2-methyl-5,6-dihydro-4H-1-oxa-3,6-diaza-benzo[e]azulene (3.3 g, 4%).
