反应详情

温度

0 °C

A solution of 6-fluoro-2-pivaloylaminopyridine (2 g) in THF (30 ml) was cooled to -78° C. and BuLi (15 mL of 1.6M in hexane) was added and the reaction stirred at 0° C. for 2 h. On re-cooling to -78° C., ethyl chloroformate (2 mL) was added and the reaction allowed to warm slowly to room temperature over 1 h. Water (10 ml) was added and the products extracted into Et2O (3×50 ml) and dried (Na2 SO4). Concentration afforded an oil which was triturated with petrol to give a solid, the isomeric 2-pivaloylamino-6-fluoropyridine-3-carboxylate (1H NMR [CDCl3 ] δ1.36 (s, 9H), 1.43 (t, 3H), 4.41 (q, 2H), 6.64 (dd, 1H), 8.45 (t, 1H), 11.34 (brs, 1H). The mother liquors were concentrated and purified by flash column chromatography (SiO2, Petrol to 5% Et2O/petrol to give ethyl 2-fluoro-6-pivaloylaminopyridine-3-carboxylate (1.2 g).

1. temperatureOn re-cooling to -78° C.
2. temperatureto warm slowly to room temperature over 1 h
3. extractionthe products extracted into Et2O (3×50 ml)
4. customdried (Na2 SO4)
5. concentrationConcentration
6. customafforded an oil which
7. customwas triturated with petrol
8. customto give a solid
9. concentrationThe mother liquors were concentrated
10. custompurified by flash column chromatography (SiO2, Petrol to 5% Et2O/petrol