Synthesis
To 2-chloropyrimidine-4-carboxylic acid (9.A, 1.00 g, 6.3 mmol) and ethanol (0.32 g, 6.9 mmol) in dichloromethane (DCM, 10 ml) was added 1,3-dicyclohexylcarbodiimide (DCC, 1.4 g, 6.9 mmol) and the reaction mixture was stirred at room temperature overnight. After completion of the reaction, the solid by-products were removed by filtration. The filtrate was diluted by adding DCM (80 ml) and subsequently washed with brine (30 ml) and dried over anhydrous magnesium sulfate (MgSO4). The solvent was removed by evaporation under reduced pressure to give the crude product. The crude product was purified by Combi-Flash silica gel column chromatography to afford the target compound ethyl 2-chloropyrimidine-4-carboxylate (9.B, 0.74 g, 63% yield). The product was confirmed by 1H NMR (400 MHz, CDCl3): δ 8.87 (1H, d, J=4.7 Hz), 7.95 (1H, d, J=4.7 Hz), 4.51 (2H, q, J=7.4 Hz), 1.45 (3H, t, J=7.0 Hz). The mass spectrum (ESI+) showed m/e: 187.0 ([M+H]+).
References
[1] Patent: WO2010/93849, 2010, A2. Location in patent: Page/Page column 53
[2] Patent: WO2014/69963, 2014, A1. Location in patent: Paragraph 616-617
