反应详情

温度

-40 °C

To a solution of 2-bromo-5-methylpyridine 49 (1.73 g, 10 mmol) in dry ether (20 ml), cooled to −78° C., was added n-butyllithium (6.25 ml of 1.6M solution in hexanes, 10 mmol, 1 equiv) dropwise. The reaction mixture was allowed to warm to −40° C. for 15 min, then cooled back to −78° C. again. N,N-dimethylacetamide (1.023 ml, 11 mmol, 1.1 equiv) was added dropwise and the mixture was stirred at −78° C. for 2 h. Saturated aqueous ammonium chloride (10 ml) was added and the organic layer was separated. The aqueous layer was extracted with ether (3×10 ml) and the combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo to give an oily residue that was subjected to flash column chromatography using (5% methanol in methylene chloride) to give compound 51 (0.977 g, 72%) as a yellow oil: TLC Rf=0.48 (silica gel, 25% EtOAc/hexanes); 1H NMR (400 MHz, CDCl3) δ 8.5-8.48 (m, 1H), 7.96-7.93 (d, 3J=8 Hz, 1H), 7.63-7.60 (m, 1H), 2.70 (s, 3H), 2.414 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 200.239, 151.741, 149.704, 137.786, 137.442, 121.663, 26.017, 18.969; HRMS calcd for C8H9NO+Na+ 158.0582; found 158.0580 [M+Na+].

1. temperaturecooled back to −78° C. again
2. customthe organic layer was separated
3. extractionThe aqueous layer was extracted with ether (3×10 ml)
4. dry with materialthe combined organic layers were dried over anhydrous sodium sulfate
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customto give an oily residue that