Example 5 Preparation of 2-chloropyrimidine-4-carboxamide: Ammonia was passed into 20 mL of tetrahydrofuran for 35 minutes at -6 °C. The reaction system was then warmed to 10 °C and 1.5 g (8.47 mmol) of 2-chloropyrimidine-4-carbonyl chloride was added. The reaction solution was stirred at room temperature for 45 min. Upon completion of the reaction, the reaction solution was concentrated using a rotary evaporator and the residue was poured into 90 mL of saturated NaHCO3 solution. The aqueous phase was extracted three times with 50 mL of ethyl acetate. The organic phases were combined, washed with saturated NaCl solution, dried over anhydrous Na2SO4 and concentrated again using a rotary evaporator. After drying under high vacuum, 1.07 g of white solid product was obtained in 80% yield (based on 2-chloropyrimidine-4-carbonyl chloride). The melting point of the product ranged from 147.2 °C to 151.4 °C. The product was characterized by the following data: 1H-NMR (CDCl3, 300 MHz) δ (ppm): 6.2 (br.s), 7.25 (s), 7.7 (br.s), 8.1 (d), 8.9 (d).
