Synthesis of 2,4-dichloro-6-trifluoromethylpyrimidine (XXVII): 6-(trifluoromethyl)uracil (XXVI) (10.0 g, 55 mmol) was dissolved in anhydrous acetonitrile (50 mL) under dry conditions. Subsequently, N,N-dimethylaniline (6.5 mL, 51 mmol) and phosphorus oxychloride (POCl3) (19 mL, 204 mmol) were added sequentially to the reaction system. Almost complete dissolution of the solids was observed, forming a dark colored solution. The reaction mixture was heated to reflux and the reflux reaction was maintained for 6 hours. Upon completion of the reaction, the heating was stopped and the volatile components were removed under reduced pressure. The residue was dissolved in ether (Et2O) (300 mL), the resulting ether solution was washed sequentially with deionized water (2 x 200 mL), dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated to give 2,4-dichloro-6-trifluoromethylpyrimidine (XXVII) as a yellow oil (11.3 g, 94% yield). The product was characterized by 1H NMR (CDCl3): δ 7.7 (s, 1H); GC/MS analysis showed m/z (relative abundance) 220 (12), 218 (67), 216 (100).
