5-Bromo-2-fluoropyridine → (2-Amino-5-bromo-pyridin-3-yl)-(6-fluoro-pyridin-3-yl)methanone

Beteiligte Stoffe

Reaktionsschritte

To a solution of 5-bromo-2-fluoropyridine (5.6 ml, 54.2 mmol) in THF (50 ml) at 0° C. under nitrogen was added dropwise a 2 M solution of iso-propylmagnesium chloride in THF (27 ml) over a period of 10 minutes. The ice bath was removed and the reaction mixture was stirred at room temperature for 2 hours. The resulting slurry was added dropwise via cannula to a solution of 2-amino-5-bromo-N-methoxy-N-methyl-nicotinamide hydrochloride (3.0 g, 11.5 mmol) in THF (50 ml) at room temperature under nitrogen over a period of 30 minutes. After stirring for 3 hours, the reaction was quenched by addition of a saturated aqueous solution of ammonium chloride (50 ml) at 0° C. and the mixture was stirred at room temperature for another 20 minutes. Water was added and the mixture was extracted with ethyl acetate (three times). The combined organic layers were dried over sodium sulfate, then filtered and concentrated. Crystallization from methanol (ca. 60 ml) afforded the title compound as dark yellow crystals (1.48 g, 49% yield). 1H NMR (DMSO-d6) δ 8.49 (s, 1H), 8.34 (d, J=1.5 Hz, 1H), 8.23 (dt, J=2.5, 8.0 Hz, 1H), 7.81 (d, J=2.5 Hz, 1H), 7.74 (broad s, 2H), 7.36 (dd, J=2.0, 8.0 Hz, 1H); MS: m/z 295.9, 297.9 [MH]+.

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