Synthesis
General procedure for the synthesis of 4-chloro-2-methylthio-6-trifluoromethylpyrimidines from 6-trifluoromethyl-4-hydroxy-2-methylthiopyrimidines: 2-(methylthio)-6-(trifluoromethyl)pyrimidin-4-ol (43-01) (1.4 g, 6.67 mmol) was dissolved in phosphorus oxychloride (POCl3, 15 mL) and the reaction was carried out under reflux for 3 h at 120 °C. The reaction was carried out under vacuum. Upon completion of the reaction, the mixture was cooled to room temperature and the excess POCl3 was subsequently removed under vacuum.The residue was extracted three times with dichloromethane (DCM) and ice water. The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate (Na2SO4), and concentrated under reduced pressure to afford 1.38 g of 4-chloro-2-(methylthio)-6-(trifluoromethyl)pyrimidine as a light yellow oil in 90% yield. Analyzed by liquid chromatography-mass spectrometry (LC-MS, ESI), the molecular ion peak m/z was measured to be 229.0 [C6H5ClF3N2S+], which was consistent with the theoretically calculated value.
References
[1] ACS Medicinal Chemistry Letters, 2017, vol. 8, # 4, p. 407 - 412
[2] Patent: WO2018/14802, 2018, A1. Location in patent: Paragraph 0232
[3] Journal of Heterocyclic Chemistry, 1983, vol. 20, # 1, p. 219 - 223
[4] Patent: WO2010/134478, 2010, A1. Location in patent: Page/Page column 182
