General procedure for the synthesis of 2-chloropyrimidine-4-carboxamide from 2-chloropyrimidine-4-carboxylic acid: 2-chloropyrimidine-4-carboxylic acid (500 mg, 1.00 eq.) was dissolved in thionyl chloride (10 mL) and the reaction was heated to 90 °C for 30 min. Upon completion of the reaction, the excess thionyl chloride was removed by concentration under reduced pressure. The residue was cooled to 0 °C and ammonium hydroxide solution (20 mL) was slowly added. The reaction mixture was extracted with dichloromethane (20 mL x 3), the organic phases were combined and dried over anhydrous sodium sulfate. After filtration, the organic phase was concentrated under reduced pressure to give 320 mg of 2-chloropyrimidine-4-carboxamide as a white solid. The product was analyzed by LC-MS (electrospray ionization, m/z): 158 [M+H]+.
