Etizolam → ethyl 6-amino-4-(2-chlorophenyl)-2-ethyl-9-methyl-6H-thieno[3,2-f][1,2,4]-triazolo[4,3-a][1,4]diazepine-6-carboxylate

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To 500 ml of diethyl carbonate were added 22.0 g of 4-(2-chlorophenyl)-2-ethyl-9-methyl-6H-thieno[3,2-f][1,2,4]-triazolo[4,3-a][1,4]diazepine and 4.3 g of sodium hydride, and the mixture was heated. Hydrogen gas began to generate at about 100° C., while the solution gradually colored violet. After 30 minutes' reflux, the mixture was cooled to 20° C., whereto 16.0 g of O-(2,4-dinitrophenyl)hydroxylamine was added. The mixture was stirred for 2 hours. After the completion of the reaction, the reaction mixture was poured into ice-water containing 6 ml of acetic acid. The diethyl carbonate layer was separated, washed twice with water and dried over anhydrous magnesium sulfate. Diethyl carbonate was distilled off under reduced pressure, and diisopropyl ether was added to the obtained residue to separate crystals, which were collected by filtration. The crystals were recrystallized from ethyl acetate to give 18.2 g of ethyl 6-amino-4-(2-chlorophenyl)-2-ethyl-9-methyl-6H-thieno[3,2-f][1,2,4]-triazolo[4,3-a][1,4]diazepine-6-carboxylate, m.p. 180°-181° C.

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