The general procedure for the synthesis of 4,6-dichloro-N-methylpyrimidin-2-amine and 2,6-dichloro-N-methylpyrimidin-4-amine from 2,4,6-trichloropyrimidine (0.50 g, 2.7 mmol) and monomethylamine (2 M THF solution, 3.0 mL, 6.0 mmol) was as follows: 2,4,6-trichloropyrimidine was dissolved in THF (3 mL), followed by dropwise THF solution of monomethylamine was added. The reaction mixture was slowly warmed to room temperature and stirred continuously for 30 min, and the formation of the target product was confirmed by LCMS monitoring. Upon completion of the reaction, the reaction was quenched with deionized water (10 mL) and extracted with ethyl acetate (2 × 10 mL). The organic phases were combined, washed with saturated saline (10 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: hexane/ethyl acetate gradient, 0-30% ethyl acetate) to isolate 2,6-dichloro-N-methyl-4-pyrimidinamine (180 mg, 1.01 mmol, 38% yield) and 4,6-dichloro-N-methyl-2-pyrimidinamine (150 mg, 0.85 mmol, 31% yield). The mass spectra (ES+) of both compounds showed m/e 178 [M+H]+.
