General procedure for the synthesis of methyl 6-chloropyrimidine-4-carboxylate from methyl 6-oxo-3,6-dihydropyrimidine-4-carboxylate: [0778] To a 2000 mL four-necked round-bottomed flask was added methyl 6-hydroxypyrimidine-4-carboxylate (115 g, 746.16 mmol, 1.00 equiv.), acetonitrile (1,200 mL), and phosphorous triclopyr (340 g, 2.22 mol, 3.00 equiv). The reaction mixture was stirred at 80 °C overnight. Upon completion of the reaction, the mixture was cooled to room temperature and concentrated under vacuum. Subsequently, the reaction mixture was diluted with 1000 mL of ethyl acetate and quenched with 1000 mL of ice water. The aqueous phase was extracted with 3 x 500 mL of ethyl acetate. The organic layers were combined, washed sequentially with 1000 mL of water and 1000 mL of saturated saline, dried over anhydrous sodium sulfate, and concentrated under vacuum. The residue was purified by silica gel column chromatography using ethyl acetate/petroleum ether (1:4) as eluent to give 76 g (59% yield) of methyl 6-chloropyrimidine-4-carboxylate as a white solid.LCMS [M + H]+ 173.
