Hydrochloric Acid → 2,3-Piperidinedione 3-(3-bromophenyl)hydrazone

참여 물질

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3-Carbethoxy-2-piperidone (4.7 g, 27.4 mmol) is stirred with potassium hydroxide (1.64 g) in water (56 mL) and kept at 30° C. on an oil bath overnight. 3-Bromoaniline (4.99 g, 29 mmol) is treated with water (50 mL) and concentrated HCl (10 mL) and cooled to 0° C. Sodium nitrite (2.46 g, 35 mmol) in water (9 mL) is added dropwise to the above solution at 0° C. and stirred for an additional 20 minutes. Urea is added to decompose the excess nitrous acid, and the diazotized solution is neutralized with 10% aqueous sodium carbonate solution (45-50 mL). The resulting solution is filtered into the solution of previously hydrolyzed 3-carbethoxy-2-piperidone (2-piperidone-3-carboxylic acid) at 0° C. After a few minutes, glacial acetic acid is added to bring the pH of the solution to 3-4. The reaction mixture is stirred at 0° C. for 5-6 h, and the yellow precipitate which resulted is filtered, washed with water, and dried to get the title compound (2.5 g, 32% yield).

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