GENERAL METHOD: Ethyl 2-cyano-3-ethoxyacrylate (2.00 g, 11.8 mmol) and 4-methylphenylhydrazine hydrochloride (2.06 g, 11.8 mmol) were dissolved in ethanol (75 mL) at room temperature, followed by the addition of triethylamine (1.65 mL, 11.8 mmol). The reaction mixture was stirred continuously at 80 °C for 8 hours. Upon completion of the reaction, the mixture was cooled to room temperature and the ethanol was removed by rotary evaporator under reduced pressure. The residue was subjected to liquid-liquid partitioning with ethyl acetate and water. The organic layer was dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with the eluent being a solvent mixture of n-hexane and ethyl acetate (3:1, v/v) to afford the target compound, ethyl 5-amino-1-tosyl-1H-pyrazole-4-carboxylate (2.42 g, 78% yield).1H NMR (300 MHz, CDCl3): δ = 7.76 (s, 1H), 7.42 (d, J = 6.9 Hz, 2H), 7.01 (d, J = 6.9 Hz, 2H), 5.19 (br s, 2H), 4.30 (q, J = 7.1 Hz, 2H), 3.82 (s, 3H), 1.36 (t, J = 7.1 Hz, 3H) ppm; MS (ESI): m/z: 262 [M + H]+.
