反应详情

A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and reflux condenser was charged with 1,4-dioxane (50 mL), 336d (1.6 g, 12.1 mmol), 5-bromo-2-nitropyridine (3.7 g, 18.2 mmol), and cesium carbonate (9.9 g, 30.2 mmol). After bubbling nitrogen through the resulting solution for 30 min, Xantphos (700 mg, 0.12 mmol) and tris(dibenzylideneacetone)-dipalladium(0) (550 mg, 0.06 mmol) were added. After three cycles of vacuum/argon flash, the reaction mixture was heated at reflux for 15 h. After this time the reaction was cooled to room temperature, filtered, and concentrated to afford a black solid as a crude product, which was further purified by column chromatography eluting with 100:1 methylene chloride/methanol to afford 336e as a yellow solid (2.6 g, 76%). MS: [M+H]+ 255. 1H NMR (500 MHz, MeOD) δ 8.20 (m, 2H), 7.52 (dd, J=9, 1H), 4.72 (m, 0.5H), 4.64 (m, 1H), 4.56 (m, 0.5H), 4.01 (m, 1H), 3.94 (m, 1H), 3.19 (m, 1H), 3.06 (m, 1H), 3.00 (m, 1H), 2.50 (m, 2H), 2.46 (s, 3H).

1. customA 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer
2. temperaturereflux condenser
3. customAfter bubbling nitrogen through the resulting solution for 30 min
4. temperatureAfter three cycles of vacuum/argon flash, the reaction mixture was heated
5. temperatureat reflux for 15 h
6. filtrationfiltered
7. concentrationconcentrated
8. customto afford a black solid as a crude product, which
9. customwas further purified by column chromatography
10. washeluting with 100:1 methylene chloride/methanol