General procedure for the synthesis of 2-methylnicotinamide from 2-methylnicotinic acid: 2-methylnicotinic acid (0.537 mg, 3.9 mmol) was dissolved in 20 mL of DMF at 0 °C, and HATU (1.56 g, 4.1 mmol) and DIPEA (0.72 mL, 4.1 mmol) were added sequentially. Subsequently, ammonia (NH3) was passed into the reaction system for 15 min. The reaction mixture was stirred overnight at room temperature. After completion of the reaction, the paste was obtained by filtration, washed with cold DMF and the filtrate was discarded. The mother liquor was concentrated and purified by normal phase chromatography with the eluent being MeOH solution of CH2Cl2/7N NH3 (93:7, v/v). The final white solid product 2-methylnicotinamide (405 mg, 76% yield) was obtained. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 1.34 (s, 9H), 1.36 (d, J = 6.64 Hz, 3H), 2.56 (s, 3H), 4.32-4.40 (m, 1H), 7.15-7.19 (m, J = 8.20 Hz, 1H), 7.68 (d, J = 8.20 Hz, 1H) .
