Synthesis
To a solution of 2,6-dichloro-N-methoxy-N-methylnicotinamide (487 mg) obtained in step (1) in tetrahydrofuran (10 mL) was slowly added methylmagnesium iodide (1.24 mL, 2M ethyl ether solution) at 0 °C. The reaction mixture was then warmed to 70 °C with continuous stirring for 72 hours. Upon completion of the reaction, the reaction was quenched by adding saturated aqueous ammonium chloride solution to the mixture and extracted with ethyl acetate. The organic layers were combined, dried with anhydrous sodium sulfate, filtered and the filtrate concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography to give the final 2,6-dichloro-3-acetylpyridine (205 mg) as a colorless oil. The product was characterized by 1H-NMR (400 MHz, CDCl3): δ 7.93 (1H, d, J = 8.1 Hz), 7.37 (1H, d, J = 8.1 Hz), 2.71 (3H, s). ESI-MS analysis showed a molecular ion peak of 190 [M + H]+.
References
[1] Patent: EP2669270, 2013, A1. Location in patent: Paragraph 0880-0882
[2] Patent: EP2878594, 2015, A1. Location in patent: Paragraph 0873; 0874
[3] Patent: WO2016/57834, 2016, A1. Location in patent: Paragraph 000591; 000601
