反应详情

温度

80 °C

To a solution of 2,5-dibromo-4-picoline (9.00 g, 35.9 mmol) in DME (96 mL), 2,4,6-trivinyl-cyclotriboroxane pyridine complex (8.63 g, 35.9 mmol) and 2 N aq. K2CO3-solution (36 mL) is added. The mixture is degassed and put under argon before Pd(PPh3)4 (746 mg, 0.646 mmol) is added. The mixture is stirred at 80° C. for 15 h, before it is cooled to rt, diluted with diethyl ether (50 mL), washed with sat. aq. NaHCO3-solution (2×30 mL), dried over MgSO4, filtered and concentrated. The crude product is purified by CC on silica gel eluting with heptane:EA 9:1 to give 5-bromo-4-methyl-2-vinyl-pyridine (7.04 g) as a yellow oil; LC-MS: tR=0.75 min; [M+1]+=198.22; 1H NMR (CDCl3): δ 2.41 (s, 3H), 5.50 (d, J=10.8 Hz, 1H), 6.21 (d, J=17.3 Hz, 1H), 6.74 (dd, J=17.3, 10.8 Hz, 1H), 7.22 (s, 1H), 8.59 (s, 1H).

1. customThe mixture is degassed
2. additionis added
3. temperatureis cooled to rt
4. washwashed with sat. aq. NaHCO3-solution (2×30 mL)
5. dry with materialdried over MgSO4
6. filtrationfiltered
7. concentrationconcentrated
8. customThe crude product is purified by CC on silica gel eluting with heptane:EA 9:1