METHOD OF SYNTHESIS OF DRUG NITRAZEPAM - 1,3-DIHYDRO-5-PHENYL-7-NITRO-2H-1,4-BENZODIAZEPINE-2-ONE Russian patent published in 1999 - IPC

FIELD: organic chemistry and chemical technology, pharmacy. SUBSTANCE: method of synthesis of the drug nitrazepam involves treatment of 2-chloro-5-nitrobenzoic acid with thionyl chloride to obtain 2-chloro-5-nitrobenzoic acid chloroanhydride. Then the latter is added to Friedel-Crafts reaction to obtain 2-chloro-5-nitro-benzophenone which then is aminated at 125-130 C by passing ammonia in the reaction mass under constant pressure 0.05-0.65 MPa to form 2-amino-5-nitrobenzophenone. Then the obtained compound is acetylated by treatment with chloroacetic acid chloroanhydride in toluene medium. Obtained 2-(2-chloroacet-amido)-5-nitrobenzophenone is converted to the crystalline end substance by cyclization with hexamethylenetetramine and 95-100% ethyl alcohol in the presence of ammonium chloride followed by treatment of reaction mass with concentrated sulfuric acid at mole ratio of indicated components = 1:(1.5-2.5):(16-54):(1.5-3): :(4-12), respectively, and acid neutralization. EFFECT: increased yield and quality indices of nitrazepam. 5 tbl, 7 ex