1-(3-Carboxypyrid-2-yl)-2-phenyl-4-methyl-piperazine

61337-88-0

61338-13-4

Example 5: Preparation of 1-(3-carboxypyridin-2-yl)-4-methyl-2-phenylpiperazine Potassium hydroxide (150 g, flakes, 85% purity) was added to 1-(3-cyanopyridin-2-yl)-4-methyl-2-phenylpiperazine (54 g) with 75 mL of water and 6.5 g of dimethylsulfoxide (DMSO). The reaction mixture was heated to 145-150 °C and the reaction was stirred at this temperature for 8 hours. Upon completion of the reaction, the inorganic phase containing water and potassium hydroxide was separated and the organic phase containing mainly product oil was cooled. Subsequently, fresh water and toluene were added to the system to separate the two phases. The aqueous phase was neutralized with hydrochloric acid (HCl) to pH=6.5-7. The aqueous phase was evaporated and toluene was added under pH=6.5-7 conditions. The inorganic salt was removed by filtration and the toluene solution was evaporated to dryness to give 52 g of 1-(3-carboxypyridin-2-yl)-4-methyl-2-phenylpiperazine in 90% yield.