General procedure for the synthesis of ethyl 3,5-diamino-1H-pyrazole-4-carboxylate from ethyl (Z)-3-amino-4,4,4-trichloro-2-cyano-but-2-enoate: hydrazine (2.19 mL, 70 mmol) was added to ethyl (Z)-3-amino-4,4,4-trichloro-2-cyano-but-2-enoate (15.0 g, 58 mmol) in DMF (50 mL) solution. The reaction mixture was heated to 100 °C and kept for 1 h, followed by cooling to room temperature. The DMF was removed under vacuum and the residue was slurried in a 95:5 (v/v) mixture of DCM and 2 M methanol ammonia solution. The resulting precipitate was collected by filtration, washed with a 95:5 mixture of DCM:MeOH and dried under vacuum to afford 5.72 g (58% yield) of ethyl 3,5-diamino-1H-pyrazole-4-carboxylate as a white solid.1H NMR (400 MHz, DMSO) δ 10.53 (s, 1H), 5.28 (br, 4H), 4.14 (q, J = 7.1 Hz, 2H), 1.33-1.15 (t, J = 7.1 Hz, 3H).
