A solution of tetrahydrofuran (10 mL) of 2,4-dibromopyrimidine (438.4 mg, 1.84 mmol) and potassium carbonate (1.27 g, 9.21 mmol) was mixed and stirred at room temperature for 5 min. Subsequently, morpholine (174.8 μL, 2.03 mmol) was added dropwise and the reaction mixture continued to be stirred at room temperature for 5 hours. Upon completion of the reaction, the mixture was filtered, the filtrate was collected and the solvent was removed by concentration under reduced pressure. The crude product was purified by silica gel column chromatography using hexane and ethyl acetate as eluents to afford 4-(4-bromopyrimidin-2-yl)morpholine (28a) and 4-(2-bromopyrimidin-4-yl)morpholine (28b) in 19% and 66% yields, respectively.
4-(4-Bromopyrimidin-2-yl)morpholine (28a): white solid in 19% yield.1H NMR (500 MHz, CDCl3) δ ppm 3.74-3.77 (m, 4H), 3.79-3.83 (m, 4H), 6.70 (d, J = 4.88 Hz, 1H), 8.05 (d, J = 4.88 Hz, 1H). LCMS m/z found 246.0, [M + H]+.
4-(2-Bromopyrimidin-4-yl)morpholine (28b): white solid, 66% yield.1H NMR (500 MHz, CDCl3) δ ppm 3.66 (br.s, 4H), 3.76-3.83 (m, 4H), 6.43 (d, J = 6.35 Hz, 1H), 8.02 (d, J = 6.35 Hz, 1H).LCMS m /z found 246.0, [M + H]+.
