General procedure for the synthesis of methyl 2,4-dichloro-6-methylpyrimidine-5-carboxylate from methyl 2,4-dihydroxy-6-methylpyridine-5-carboxylate: 6-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid methyl ester (1 g, 5.43 mmol) was suspended in POCl3 (10 mL) and N,N-dimethylaniline (10 drops ). The reaction mixture was heated at 105 °C for 6 h until a clarified solution was formed. Upon completion of the reaction, the mixture was cooled to room temperature, concentrated under reduced pressure and subsequently poured into ice water and extracted with ethyl acetate (EtOAc). The organic phases were combined, washed sequentially with water and saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give methyl 2,4-dichloro-6-methylpyrimidine-5-carboxylate (940 mg, 78% yield) as a yellow-green solid. Mass spectrometry analysis: [M + H]+ C7H6Cl2N2O2 calculated value was 222, measured values were 221 and 223.
