General procedure for the synthesis of 1-methyl-5-aminopyrazole (9) from 3-methoxyacrylonitrile (1a) and methylhydrazine (2b): methylhydrazine (2b) (0.25 mL, 4.7 mmol) and 3-methoxyacrylonitrile (1a) (0.20 mL, 2.4 mmol) were dissolved in toluene/acetic acid (4:1 v/v; 5 mL) solvent mixture. The reaction mixture was placed in a sealed pressure rated Pyrex tube (10 mL) and microwave irradiated for 1 h at 120 °C using a CEM Discover microwave synthesizer set at an initial power of 100 W. The reaction was carried out using a CEM Discover microwave synthesizer. After completion of the reaction, the reaction mixture was cooled in a stream of compressed air. Subsequently, the reaction mixture was neutralized with saturated aqueous NaHCO3 solution and extracted with EtOAc (3 × 20 mL). The organic layers were combined, washed sequentially with water and brine, dried over MgSO4, and the solvent was evaporated in vacuum to afford 1-methyl-5-aminopyrazole (0.22 g, 97%) as a light brown solid with a melting point of 71-73 °C (literature value: 71-72 °C). The product was confirmed by high-resolution mass spectrometry (measured value: 97.0640, C4H7N3 [M] theoretical value: 97.0637).1H NMR (400 MHz; DMSO-d6) δ 7.60 (1H, d, J = 2.0 Hz, H-3), 5.15 (1H, d, J = 2.0 Hz, H-4), 3.85 (2H, br s, with D2O exchange, NH2), 3.50 (3H, s, Me); 13C NMR (126 MHz; DMSO-d6) δ 145.6 (C), 138.5 (CH), 90.8 (CH), 34.0 (Me); LRMS (APcI) m/z (relative intensity) 97 (M+, 100).
