反应详情

温度

-78 °C

To a solution of 5-cyano-2-bromopyrazine (1.02 g, 5.54 mmol) in anhydrous toluene (15 mL) at −78° C. was added 1 M diisobutyl aluminum hydride (8.32 mmol) in CH2Cl2 (8.3 mL). The reaction mixture was stirred at −78° C. for 15 min, warmed to room temperature, stirred for 26 h, and then diluted with MeOH (4 mL) and stirred for 30 min at room temperature before addition of 10% H2SO4 (55 mL). The resulting solution was stirred for 1.75 h and extracted with EtOAc (100 mL, 50 mL). After solvent removal at reduced pressure, the residue was chromatographed (11% to 14% EtOAc/hexane) to give 289 mg (28%) of 5-bromo-pyrazine-2-carbaldehyde as an orange solid, mp 56-58° C. IR 2960, 1654, 1546, 1111 cm−1; 1H NMR (CDCl3) δ 8.83 (d, J=1.24 Hz, 1H, 6-PyrH), 8.91 (d, J=1.24 Hz, 1H, 3-PyrH), 10.13 ppm (s, 1H, CHO). HRMS calcd C5H3BrN2O [M+H]+ 186.9501. found 186.9496.

1. temperaturewarmed to room temperature
2. stirringstirred for 26 h
3. stirringThe resulting solution was stirred for 1.75 h
4. extractionextracted with EtOAc (100 mL, 50 mL)
5. customAfter solvent removal at reduced pressure
6. customthe residue was chromatographed (11% to 14% EtOAc/hexane)