4H-IMIDAZO[1,5-A][1,4]BENZODIAZEPINE-3-CARBOXYLIC ACID, 8-FLUORO-5,6-DIHYDRO-5-METHYL-6-OXO- synthesis

78755-81-4

84378-44-9

The general procedure for the synthesis of 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo[F]imidazo[1,5-a][1,4]diazepine-3-carboxylic acid from ethyl 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo[f]imidazo[1,5-a][1,4]diazepine-3-carboxylate is as follows: 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo[1,5-a][1,4]diazepine-3-carboxylic acid was prepared from 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo[1,5-a][1,4]diazepine-3-carboxylic acid as follows. -6-oxo-5,6-dihydro-4H-benzo[F]imidazo[1,5-a][1,4]diazepine-3-carboxylic acid ethyl ester (0.5 g, 1.7 mmol) was suspended in tetrahydrofuran (THF, 50 mL). Aqueous sodium hydroxide (2M, 10 mL) was added to the suspension to completely dissolve the solid. The reaction mixture was stirred at room temperature until completion of the reaction was confirmed by thin layer chromatography (TLC) monitoring. Upon completion of the reaction, the solvent was evaporated under reduced pressure. The residue was dissolved in water and acidified with 2M hydrochloric acid to precipitate the target product as a solid. The solid product was collected by filtration and dried under vacuum to afford 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo[f]imidazo[1,5-a][1,4]diazepine-3-carboxylic acid as a colorless solid (0.45 g, 100% yield). The structure of the product was confirmed by 1H NMR (CD3OD): δ 3.24 (3H, s, CH3), 4.62 (1H, br d, J = 15.4 Hz, CHaHb), 5.19 (1H, br d, J = 15.4 Hz, CHaHb), 7.62 (1H, ddd, JHF = 12.5 Hz, JHH = 7.7 and 3.1 Hz. CFCHCH), 7.79 (1H, dd, JHF = 8.9 Hz, JHH = 3.1 Hz, CCHCF), 7.87 (1H, dd, JHF = 9.1 Hz, JHH = 4.5 Hz, CHCHCF), 9.63 (1H, s, NCHN).