118133-15-6

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541-41-3

118133-15-6

Example 1- Preparation of 1-(ethoxycarbonyl)piperidine-4-carboxylic acid Sodium hydroxide (154.8 g) was dissolved in pure water (750 ml) at 0-10°C and isopiperidine carboxylic acid (250 g) was added. Subsequently, ethyl chloroformate (231 ml) was added slowly and dropwise at 5-20°C. The reaction mixture was warmed up to 20-30°C and maintained at this temperature for 3 hours. Upon completion of the reaction, the reaction solution was acidified with hydrochloric acid to pH 1-2. Toluene (750 ml) was added to the reaction solution and stirred at 25-30 °C for 15 min. The organic layer was separated and concentrated under reduced pressure at below 70 °C to give a residue. The residue was mixed with cyclohexane (1250 ml), heated to 60-70 °C then cooled to 25-30 °C and kept for 1 hour. The resulting solid was filtered, washed with cyclohexane (1250 ml) and dried at 50-55 °C. Yield: 92%.