反应详情

A mixture of 2,4-dibromothiophene (3 g, 12.4 mmol) and pyridine-3-boronic acid-1,3-propanediol cyclic ester (2.22 g, 13.6 mmol) in EtOH (30 ml) and toluene (30 ml) together with 2N Na2CO3 solution (12.4 ml) was degassed with a stream of N2 for 10 min. Tetrakis-(triphenylphosphine)palladium(0) (0.25 g, 0.22 mmol) was added and the reaction heated at reflux for 4 h. The mixture was concentrated under reduced pressure to remove the organic solvents and H2O (100 ml) was added. The organics were extracted with EtOAc (200 ml) and then washed with brine (75 ml), dried (MgSO4), and concentrated under vacuum. The resulting crude residue was purified by column chromatography on silica using 70% diethyl ether in hexane as the eluent to yield 3-(4-bromothien-2-yl)pyridine (2.15 g, 75%): δH (360 MHz, CDCl3) 7.26 (1H, s), 7.32 (1H, dd, J 8.6 and 4.9), 7.81 (1H, dt, J 8.6 and 1.7), 8.56 (1H, s), 8.86 (1H, s); m/z (ES+) 240, 242 (1:1) (M++H).

1. customwas degassed with a stream of N2 for 10 min
2. temperaturethe reaction heated
3. temperatureat reflux for 4 h
4. concentrationThe mixture was concentrated under reduced pressure
5. customto remove the organic solvents and H2O (100 ml)
6. additionwas added
7. extractionThe organics were extracted with EtOAc (200 ml)
8. washwashed with brine (75 ml)
9. dry with materialdried (MgSO4)
10. concentrationconcentrated under vacuum
11. customThe resulting crude residue was purified by column chromatography on silica using 70% diethyl ether in hexane as the eluent