Phosphorus pentachloride → 5-(4-methyl-1-homopiperazinyl)-11H-imidazo[1,2-c][1,3]benzodiazepine

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Reaction Steps

To a suspension of 2.46 g of 1-[2-(2-imidazolylmethyl)phenylcarbamoyl]-4-methylhomopiperazine in 19.4 ml of phosphorus oxychloride is added at once 1.66 g of phosphorous pentachloride and the mixture is stirred at room temperature for 4 hours. The mixture is evaporated to dryness, the residue is suspended in 45.2 ml of methylene chloride, the suspension is cooled to 0° and 21.4 ml of triethylamine are added dropwise with stirring over a period of 15 minutes. The mixture is allowed to warm up to room temperature, stirred for 1.5 hours and poured into 10% aqueous potassium carbonate. The methylene chloride layer is separated, the aqueous layer is washed with methylene chloride and the combined methylene chloride extracts are dried over MgSO4, decolorized with charcoal and evaporated to dryness. The residue is purified by column chromatography with 50 g of silica gel, using methylene chloride-methanol-conc. ammonium hydroxide (300:50:1) as eluent to give 5-(4-methyl-1-homopiperazinyl)-11H-imidazo[1,2-c][1,3]benzodiazepine as an oil. This free base is dissolved in acetone and treated with maleic acid to give 5-(4-methyl-1-homopiperazinyl)-11H-imidazo[1,2-c][1,3]benzodiazepine monomaleate, m.p. 160°-163°.

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