反应详情

Ex-46C: 2-(5-[1.3]Dioxolan-2-yl-2,4-dimethoxy-phenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (Ex-46B, 2.22 g, 6.60 mmol, containing borolane impurity) was dissolved in DME (60 mL) and 2-iodopyrazine (0.59 mL, 6.0 mmol) was added. 2M aqueous Na2CO3 (17.8 mL, 35.6 mmol) was added and the mixture was purged with nitrogen for 20 min. Tetrakis(triphenylphosphine)palladium(0) (0.69 g, 0.60 mmol) was added and the mixture was heated at reflux for 2.5 h. After cooling, water (50 mL) was added and the mixture was extracted with CH2Cl2 (2×30 mL). The organic phase was washed with brine (1×20 mL), dried over sodium sulfate, filtered, and concentrated. Purification of the resulting yellow-orange solids via silica chromatography (50–80% EtOAc/hexanes) provided 1.02 g of 2-(5-[1,3]dioxolan-2-yl-2,4-dimethoxy-phenyl)-pyrazine as a yellow solid (59% yield). 1H-NMR (CDCl3) δ 9.10 (d, J=2 Hz, 1H), 8.61 (m, 1H), 8.39 (d, J=3 Hz, 1H), 8.07 (s, 1H), 6.57 (s, 1H), 6.14 (s, 1H), 4.13–4.18 (m, 2H), 4.01–4.05 (m, 2H), 3.95 (s, 3H), 3.93 (s, 3H).

1. customthe mixture was purged with nitrogen for 20 min
2. temperaturethe mixture was heated
3. temperatureat reflux for 2.5 h
4. temperatureAfter cooling
5. extractionthe mixture was extracted with CH2Cl2 (2×30 mL)
6. washThe organic phase was washed with brine (1×20 mL)
7. dry with materialdried over sodium sulfate
8. filtrationfiltered
9. concentrationconcentrated
10. customPurification of the resulting yellow-orange solids via silica chromatography (50–80% EtOAc/hexanes)