General procedure for the synthesis of 4-chloro-2-(methylthio)pyrimidine-5-carbaldehyde from (4-chloro-2-(methylthio)pyrimidin-5-yl)methanol: Activated manganese(IV) oxide (38.1 g, 439 mmol, 5 μm) was added to (4-chloro-2-(methylthio)pyrimidin-5-yl)methanol (16.73 g, 87.8 mmol) in a chloroform ( 800 mL) solution. The reaction mixture was stirred overnight at room temperature and after completion of the reaction, it was filtered through a pad of diatomaceous earth to remove solid impurities. The filtrate was concentrated under reduced pressure to afford 4-chloro-2-(methylthio)pyrimidine-5-carbaldehyde (13.7 g, 82.8% yield). The product was characterized by 1H NMR (500 MHz, CDCl3): δ 10.31 (s, 1H), 8.88 (s, 1H), 2.65 (s, 3H) ppm.
[1] Patent: WO2009/85185, 2009, A1. Location in patent: Page/Page column 129
[2] Patent: US2015/31674, 2015, A1. Location in patent: Paragraph 0317
[3] ACS Medicinal Chemistry Letters, 2015, vol. 6, # 12, p. 1241 - 1246
[4] Patent: EP2112150, 2009, A1. Location in patent: Page/Page column 26; 28
[5] Patent: US2011/257207, 2011, A1. Location in patent: Page/Page column 21