反应详情

To a solution of 2-bromopyridine (5 ml, 52 mmol) in Et2O (60 ml) was added 40 ml of a n-butyllithium (1.6M in hexane, 64 mmol) drop wise at −40° C. over 30 min under a nitrogen atmosphere. The resulting yellow solution was stirred for a further 1 hr at −50° C. to −30° C. In a separate flask, a solution of 2-amino-5-chlorobenzoic acid (2.05 g, 12 mmol) in dry THF (90 ml), under nitrogen atmosphere and with ice-cooling, was added in one portion to the solution prepared as described above. The reaction mixture was stirred for 2 hrs at 0° C. and then chlorotrimethylsilane (30 ml) was added at 0° C. with stirring. The reaction mixture was allowed to warm to room temperature and 1 N HCl aq (100 ml) was added. The resulting two-phase system was separated. The aqueous phase was adjusted to pH12 with 6N NaOH solution and extracted with ethyl acetate (2×150 ml). The combined organic extractions were dried over Na2SO4. After removal of solvent, the residue was purified by the flash chromatography using ethyl acetate/hexane (1:4) as eluent. Crystallization of the product from Et2O/hexane mixture gave 1.26 g (45%) of desired product as yellow solid. 1H-NMR (DMSO-d6, 500 MHz): δ 6.90 (1H, d, J=9 Hz), 7.31 (1H, dd, J=9 and 2.5 Hz), 7.40 (2H, br), 7.53 (1H, d, J=2.5 Hz), 7.61 (1H, m), 7.79 (1H, d, J=8 Hz), 8.03 (1H, m), 8.69 (1H, m). MS: (ESI+): 233.2 (M+1).

1. additionwas added in one portion to the solution
2. customprepared
3. stirringThe reaction mixture was stirred for 2 hrs at 0° C.
4. stirringwith stirring
5. customThe resulting two-phase system was separated
6. extractionextracted with ethyl acetate (2×150 ml)
7. extractionThe combined organic extractions
8. dry with materialwere dried over Na2SO4
9. customAfter removal of solvent
10. customthe residue was purified by the flash chromatography
11. customCrystallization of the product from Et2O/hexane mixture