Synthesis
General procedure for the synthesis of 4-chloro-8-methylquinazoline from 8-methyl-4-quinazolone: Phosphorus oxychloride (800 mL) was added to a 2 L round-bottomed flask under nitrogen protection. Subsequently, 8-methylquinazolin-4(3H)-one (125 g) was added in batches. The reaction mixture was heated to 120 °C and refluxed for 12 hours. The reaction process was monitored by thin layer chromatography (TLC) and liquid chromatography-mass spectrometry (LCMS). Upon completion of the reaction, the mixture was cooled to room temperature and evaporated to dryness under reduced pressure. The resulting residue was dissolved in dichloromethane (DCM, 500 mL) and quenched by slow pouring into a pre-cooled saturated potassium carbonate (K2CO3) solution under continuous stirring. The organic layer was separated, washed with brine, dried over anhydrous sodium sulfate, and subsequently concentrated under vacuum to afford 4-chloro-8-methylquinazoline (120 g, 86% yield) as a yellow solid. The product could be used for subsequent reactions without further purification. Mass spectrometry (MS) data: m/z = 179/181 [M + H]+.
References
[1] Patent: WO2017/106607, 2017, A1. Location in patent: Paragraph 00224
[2] Synthetic Communications, 2011, vol. 41, # 24, p. 3644 - 3653
[3] Patent: WO2013/106756, 2013, A2. Location in patent: Page/Page column 40
[4] Patent: US9822108, 2017, B2. Location in patent: Page/Page column 42
[5] Bioorganic and Medicinal Chemistry, 1996, vol. 4, # 8, p. 1203 - 1207
