Benzyl Bromide → 3-benzyl-5-bromo-2-(methylthio)pyrimidin-4(3H)-one

Participants

Reaction Steps

5-bromo-2-(methylthio)pyrimidin-4(3H)-one (3.63 g, 16.4 mmol) was suspended in THF (80 ml) and CaH2 powder (1.29, 32.3 mmol) and benzyl bromide (2.6 ml, 22 mmol) were added. The reaction flask was fitted with a reflux condenser and placed in a preheated oil bath (65 C-70 C) and stirred overnight. After 15.5 hours, more benzyl bromide (0.7 ml, 6 mmol) was added, and the temperature of the oil bath was raised to 87 C to achieve reflux. After 19 more hours, the reaction was cooled to 0 C and quenched cautiously with ice water first, and then with water (40 ml). The reaction was warmed to room temperature and stirred as more water (40 ml) and then brine (30 ml) were added. The reaction was extracted with a DCM/MeOH mixture, and the organic extractions were combined, dried over sodium sulfate, filtered, and concentrated. The crude residue was filtered through silica gel (˜3 inches, DCM) to afford the desired 3-benzyl-5-bromo-2-(methylthio)pyrimidin-4(3H)-one (642 mg, 2.06 mmol, 90% purity, 11% yield). MS (ESI pos. ion) m/z: 311 (MH+), 313 (MH+). Calc'd exact mass for C12H11BrN2OS: 310, 312. 1HNMR (400 MHz, CDCl3): 8.09 (s, 1H), 7.42-7.29 (m, 5H), 5.34 (s, 2H), 2.54 (s, 3H).

Provenance & Evidence