Ethyl formate → 5-Fluoro-2-methylpyrimidin-4-ol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Sodium hydride (60%, 5.0 g, 125 mmol) was washed with hexane to remove the mineral oil and dried, then suspended in THF (50 mL) and cooled to 0° C. Ethyl fluoroacetate (13.30 g, 125 mmol) and ethyl formate (15.14 mL, 187 mmol) were mixed together and added to the stirring suspension. The reaction was slowly warmed to ambient temperature and stirred 3 days. The solvent was removed. A mixture of acetamidine hydrochloride (11.81 g, 125 mmol), sodium ethoxide (8.86 g, 125 mmol), and ethanol (60 mL) were added to the reaction followed by refluxing overnight. The ethanol was removed under reduced pressure. The residue was dissolved in a minimum of water and acidified to pH=6 with concentrated HCl. The crude products were then extracted by salting out from the aqueous phase and washing exhaustively with 4:1 CHCl3/isopropanol. The combined organic phases were dried (MgSO4) and evaporated. The crude solid was purified by silica gel chromatography eluting with 5-90% EtOAc/hexane to give 5-Fluoro-2-methylpyrimidin-4(3H)-one (44a, 0.95 g, 6%) as a white solid. Rf=0.08 (75% EtOAc/hexane). 1H NMR (400 MHz, DMSO-d6): δ 2.25 (d, J=1.0 Hz, 3H), 7.93 (d, J=3.8 Hz, 1H), 12.95 (br, 1H). LCMS 129.

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