Step 2: Synthesis of 6-(difluoromethyl)pyridin-2-amine (0398)
At room temperature, 13 mL of ammonia (28 wt%) and 250 mg (1.81 mmol) of potassium carbonate were added to a solution containing 1.86 g (8.94 mmol) of 2-bromo-6-(difluoromethyl)pyridine, 64 mg (0.447 mmol) of copper (I) oxide, 80 mg (0.908 mmol) of N,N'-dimethylethylenediamine and 18 mL of ethylene glycol in a in a mixed solution. After addition, the reaction mixture was heated and stirred under reflux conditions for 22 hours. After completion of the reaction, the reaction was terminated by adding 30 mL of water and extracted with ethyl acetate (2 x 20 mL). The organic layers were combined, washed with water and then dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure and the resulting residue was purified by silica gel column chromatography (eluent: n-hexane/ethyl acetate = 9:1 to 6:4) to afford 770 mg of the target compound 6-(difluoromethyl)pyridin-2-amine (0398) as a colorless liquid.
1H-NMR (CDCl3, Me4Si, 300 MHz): δ 7.53 (dd, 1H, J = 7.2 Hz, 8.1 Hz), 6.94 (d, 1H, J = 7.2 Hz), 6.57 (d, 1H, J = 8.1 Hz), 6.42 (t, 1H, J = 56 Hz), 4.58 (brs, 2H).
