General procedure for the synthesis of 2,4-dichloro-6-methoxypyrimidine from 6-methoxypyrimidine-2,4(1H,3H)-dione: 6-methoxypyrimidine-2,4(1H,3H)-dione (15 g, 0.106 mol) was mixed with phosphorus triclosan (400 ml) and heated and refluxed for 4 h. After completion of the reaction the excess of phosphorus triclosan was removed by distillation under reduced pressure. The residue was quenched with an ice-water mixture and extracted with ethyl acetate (EtOAc). The organic phases were combined, washed with water, dried over anhydrous sodium sulfate (Na2SO4), and concentrated under reduced pressure to remove the solvent to afford 2,4-dichloro-6-methoxypyrimidine as an oil (5.5 g, 30% yield). Nuclear Magnetic Resonance Hydrogen Spectroscopy (NMR) data: δ 3.96 (3H, single peak), 6.63 (1H, single peak); Mass Spectrum (m/z): 179 [MH]+.
