The preparation of 3-Bromo-1,3,4,5-tetrahydro-2H-benzo[b]azepin-2-one is as follows:10 parts by weight of the heated melted polyphosphoric acid was added to the drying kettle, With stirring, The above 2-bromo-3,4-dihydro-N-hydroxy- (2H) -naphthalimide was added in portions at a temperature of 60 ° C, Insulation reaction for 20 hours; The reaction solution was added dropwise to 12.5 parts by weight of water to carry out hydrolysis, Still Washed to give 3-bromo-1,3,4,5-tetrahydro-2H-1-benzazepin-2-one crude; 10 parts by weight of methanol and 0.1 part by weight of activated carbon were added, Heating decolorization, After filtration, the filtrate was cooled to 10 ° C for 20 hours, centrifuged, washed and dried to give 3-bromo-1,3,4,5-tetrahydro-2H-1-benzazepan-2-one. The purity of the product was 3, 10-bromo-1,3,4,5-tetrahydro-2H-1-benzazepan-2-one as high as 99.6% and the yield was as high as 98%.
