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 was added at once 1.66 g of phosphorous pentachloride and the mixture was stirred at room temperature for 4 hours. The mixture was evaporated to dryness, the residue was suspended in 45.2 ml of methylene chloride, the suspension was cooled to 0° and 21.4 ml of triethylamine were added dropwise with stirring over a period of 15 minutes. The mixture was allowed to warm up to room temperature, stirred for 1.5 hours and poured into 10% aqueous potassium carbonate. The methylene chloride layer was separated, the aqueous layer was washed with methylene chloride and the combined methylene chloride extracts were dried over MgSO4, decolorized with charcoal and evaporated to dryness. The residue was 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 was 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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