反应详情

U.S Pat. No. 4,280,957 (hereinafter the '957 patent) describes a synthetic process for preparing midazolam, which is depicted in Scheme 2 below. This process includes reacting 2-aminomethyl-7-chloro-2,3-dihydro-5-(2-fluorophenyl)-1H-1,4-bezodiazepine (II) with acetic anhydride in dichloromethane to produce 2-acetamido-methyl-7-chloro-2,3-dihydro-5-(2-fluorophenyl)-1H-1,4-bezodiazepine (III). The latter is heated with polyphosphoric acid at 150° C. to produce 8-chloro-6-(2-fluorophenyl)-3a,4-dihydro-1-methyl-4H-imidazo[1,5-a][1,4]benzodiazepine of formula (IV), which is purified by column chromatography. Compound IV is then mixed with toluene and manganese dioxide and heated to reflux to afford midazolam base, which is crystallized from ether to yield a product with mp of 152-154° C.