99469-85-9

General procedure for the synthesis of 4,5-dichloro-2-(methylthio)pyrimidin-4-ol from 5-chloro-2-(methylthio)pyrimidin-4-ol: 5-chloro-2-(methylthio)pyrimidin-4(3H)-one (24 g, 0.136 mol) was suspended in phosphorous triclosan (POCl3, 200 mL) and heated to reflux for 2 hours. Upon completion of the reaction, the reaction mixture was cooled to room temperature and concentrated under reduced pressure to remove excess phosphorous trichloride. The residue was treated with distilled water (150 mL) and the pH was adjusted to 7~8 with aqueous potassium carbonate. the resulting mixture was extracted with dichloromethane (50 mL x 4). The organic layers were combined, washed with saturated saline (50 mL), dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and dried in vacuum to afford 4,5-dichloro-2-(methylthio)pyrimidine (23 g, 86% yield) as a light brown solid.

[1] Patent: WO2012/52948, 2012, A1. Location in patent: Page/Page column 53
[2] Acta Chemica Scandinavica, Series B: Organic Chemistry and Biochemistry, 1986, vol. 40, # 5, p. 381 - 386