1-Methylpiperazine → 4H-Thieno(3,4-b)(1,5)benzodiazepine, 7-chloro-10-(4-methyl-1-piperazinyl)-

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Reaction Steps

A solution of 0.9 g. of 7-chloro-10-(methylthio)-4H-thieno[3,4-b][1,5]benzodiazepine in 4.5 ml. of N-methylpiperazine is treated with 2-3 drops of glacial acetic acid and heated under reflux for 4 days. The solution is concentrated to dryness and the residue is warmed with dilute acetic acid. The acidic solution is filtered, cooled and made alkaline with concentrated ammonium hydroxide. The sticky precipitate is collected and dissolved in chloroform. The dried chloroform solution is concentrated under reduced pressure to give 7-chloro-10-(4-methyl-1-piperazinyl)-4H-thieno[3,4-b][1,5]benzodiazepine as an oil. An ethanolic solution of the oil is treated with 70% perchloric acid and diluted with water. The precipitate is recrystallized from methanol to give yellow crystals, m.p. 268°-270° C. (dec.).

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