反应详情

Sodium pieces (200 mg) was added portion wise to 2-propanol (0.521 g, 6.35 mmol) and the reaction was stirred for 12 h at RT. To the above thick solution, 2,6-dibromo pyridine (1 g, 4.23 mmol, Aldrich) was added and the reaction was heated to 90° C. for 2 h. The mixture was cooled to RT and the solvent was removed. The crude residue was treated with ice water (10 mL) and extracted with EtOAc (2×25 mL). The combined organic layers were dried over anhydrous Na2SO4 and concentrated. The residue was purified with silica gel column chromatography (Eluent: 0.5% EtOAc in petroleum ether) to give 2-bromo-6-isopropoxypyridine (600 mg, 66.5%) as a colorless liquid. MS (ESI, pos. ion) m/z: 216.0 (M+1); 1H-NMR (400 MHz, CDCl3): δ 7.38-7.34 (m, 1H), 6.99 (dd, J=7.2 Hz, J=4 Hz 1H), 6.60 (dd, J=8.0 Hz, J=4 Hz 1H). 5.28-5.25 (m, 1H), 1.32 (d, J=4.4 Hz, 6H). A solution of 2-bromo-6-isopropoxypyridine (1 g, 4.67 mmol) in dry THF (10 mL) was treated with n-BuLi (1.6M in hexane) (3.2 mL, 5.14 mmol) dropwise at −78° C. and the reaction was stirred at the same temperature for 30 min. Tributyl tin chloride (1.8 mL, 5.60 mmol, Aldrich) was added to the reaction at −78° C. and the reaction was stirred at the same temperature for 30 min. The mixture was treated with saturated NH4Cl solution (10 mL) and extracted with EtOAc (25 mL). The organic layer was dried over anhydrous Na2SO4, concentrated in vacuo. The residue was purified with silica gel column chromatography using (eluent: 100% petroleum ether) to give 2-isopropoxy-6-(tributylstannyl)pyridine (1 g, 50%) as a colorless liquid. 1H-NMR (300 MHz, CDCl3): δ 7.40-7.35 (m, 1H), 6.99 (dd, J=5.4, 4.5 Hz, 1H), 6.65 (dd, J=7.2, 0.6 Hz, 1H). 5.32-5.24 (m, 1H), 1.34-1.32 (m, 10H), 1.31-1.25 (m, 13H), 0.87-0.84 (m, 10H).

1. temperaturethe reaction was heated to 90° C. for 2 h
2. temperatureThe mixture was cooled to RT
3. customthe solvent was removed
4. additionThe crude residue was treated with ice water (10 mL)
5. extractionextracted with EtOAc (2×25 mL)
6. dry with materialThe combined organic layers were dried over anhydrous Na2SO4
7. concentrationconcentrated
8. customThe residue was purified with silica gel column chromatography (Eluent: 0.5% EtOAc in petroleum ether)