5-Fluorouracil → 5-Fluoro-1-(2-methylpropyl)-2,4(1H,3H)-pyrimidinedione

Participants

Reaction Steps

To a solution of 5-fluoropyrimidine-2,4(1H,3H)-dione (5.0 g, 38 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU; 6.4 g, 42 mmol) in dry CH3CN (150 mL) at room temperature and under nitrogen was added 1-bromo-2-methylpropane (5.3 g, 38 mmol) dropwise. The reaction was then heated to reflux for 18 h. After cooling to room temperature, the solvent was removed in vacuo. The crude residue was purified by normal phase chromatography (gradient, 0 to 20% EtOAc/Petroleum ether), providing 5-fluoro-1-isobutylpyrimidine-2,4(1H,3H)-dione (2.5 g, 35%) as a white solid: mp 173-174° C.; 1H NMR (400 MHz, CDCl3) δ 8.61 (s, 1H), 7.21 (d, J=5.5 Hz, 1H), 3.53 (d, J=7.5 Hz, 2H), 2.13-2.01 (m, 1H), 0.98 (d, J=6.7 Hz, 6H); ESIMS m/z 185 ([M−H]−).

Provenance & Evidence