METHOD OF SYNTHESIS OF 1,3-DIHYDRO-7-NITRO-5-PHENYL-2H-1,4- -BENZODIAZEPINE-2-ONE (NITRAZEPAM) (VARIANTS) Russian patent published in 2000 - IPC

FIELD: organic chemistry, chemical technology, pharmacy. SUBSTANCE: invention describes the novel method of synthesis of 1,3-dihydro-7-nitro- -5-phenyl-2H-1,4-benzodiazepine-2-one by interaction of 2-chloro-5-nitrobenzophenone with ethylenediamine in medium of organic solvent at heating followed by oxidation of obtained 2,3-dihydro-7-nitro-5-phenyl-1H-1,4-benzodiazepine with hexavalent chrome compound in concentrated sulfuric acid in solvent medium and isolation of the end product. Interaction of 2-chloro-5-nitrobenzophenone with ethylenediamine is carried out in isopropyl alcohol at 70-80 C, oxidation of 2,3-dihydro- -7-nitro-5-phenyl-1H-1,4-benzodiazepine is carried out in acetone or acetonitrile medium at 18-20 C with sodium (potassium) bichromate saturated aqueous solution at mole ratio of components 2,3-dihydro-7-nitro-5-phenyl-1H-1,4-benzo-diazepine : sodium (potassium) bichromate : concentrated sulfuric acid : acetone or acetonitrile = 1: (0.92-1.02):(7.5- -8.5):(72-76). Isolation of the end product is carried out by separation of precipitate from reaction mass and treatment of the latter with alkali in aqueous medium to pH = 3.0-3.5. EFFECT: improved technology of synthesis, increased yield of end product. 2 cl, 6 ex