[Synthesis]
4.1.1 Synthesis of N-(5-methyl-1H-pyrazol-3-yl)-acetamide (2): 5-methyl-1H-pyrazol-3-amine (1) (10 g, 103 mmol) was dissolved in 100 mL of distilled water and sodium bicarbonate (NaHCO3) (26 g, 309 mmol) was added slowly. Subsequently, acetic anhydride (19.5 mL, 206 mmol) was added dropwise and the resulting suspension was heated and refluxed for 16 hours (the reaction process was monitored by thin layer chromatography (TLC)). Upon completion of the reaction, the mixture was cooled to room temperature and white crystals were observed to precipitate slowly. The precipitate was collected by filtration, washed with distilled water and dried to afford the target product N-(5-methyl-1H-pyrazol-3-yl)-acetamide (2) (6.2 g, 44 mmol, 43% yield), which did not require further purification. The melting point of the product was 210-211 °C; 1H NMR (400 MHz, DMSO-d6) δ 11.92 (s, 1H), 10.19 (s, 1H), 6.24 (s, 1H), 2.17 (s, 3H), 1.96 (s, 3H). |