反应详情

Under an argon atmosphere, 2-amino-3-benzyl-5-bromopyrazine (c-10) (1.66 g, 6.27 mmol) was dissolved in 1,2-dimethoxyethane (17 mL) and ethanol (13 mL) and to this were sequentially added 2 M aqueous solution of sodium carbonate (31.4 mL, 62.8 mmol), dichlorobis(triphenylphosphine) palladium(II) (221 mg, 315 μmol), and phenyl boronic acid (996 mg, 8.16 mmol) while stirring at room temperature and then stirred at 90° C. for 2.5 h. After cooling to room temperature, to this were added saturated brine and ethyl acetate to stop the reaction. The organic layer was washed with saturated brine and then dried over anhydrous sodium sulfate. After removing anhydrous sodium sulfate by filtration, the filtrate was concentrated under reduced pressure with a rotary evaporator. After purifying the residue by column chromatography (50 g, n-hexane/ethyl acetate=3/2→1/1), the obtained solid was recrystallized twice from ethyl acetate to give 2-amino-3-benzyl-5-phenylpyrazine (c-41) as a yellow solid (982 mg, 59.9%). Rf=0.30 (n-hexane/ethyl acetate=3/2). 1H NMR (400 MHz, DMSO-d6) δ 4.07 (s, 2H), 6.41 (s, 2H), 7.18 (t, J=7.5 Hz, 1H), 7.24-7.31 (m, 3H), 7.34 (d, J=7.3 Hz, 2H), 7.40 (t, J=7.5 Hz, 2H), 7.90 (d, J=7.8 Hz, 2H), 8.41 (s, 1H). IR (KBr, cm−1) 596, 664, 694, 716, 733, 754, 773, 908, 937, 1070, 1152, 1217, 1233, 1396, 1427, 1450, 1462, 1493, 1543, 1636, 3024, 3125, 3291, 3487. HRMS (EI+) m/z 261.1269 (M, C17H15N3 requires 261.1266).

1. stirringstirred at 90° C. for 2.5 h
2. temperatureAfter cooling to room temperature
3. customthe reaction
4. washThe organic layer was washed with saturated brine
5. dry with materialdried over anhydrous sodium sulfate
6. customAfter removing anhydrous sodium sulfate
7. filtrationby filtration
8. concentrationthe filtrate was concentrated under reduced pressure with a rotary evaporator
9. customAfter purifying the residue by column chromatography (50 g, n-hexane/ethyl acetate=3/2→1/1)
10. customthe obtained solid was recrystallized twice from ethyl acetate