Dimethylformamide → 3-(1-methylcyclopropyl)-1H-1,2,4-triazol-5(4H)-one

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2-Methylcyclopropanecarboxylic acid (0.86 g, 8.6 mmol) was dissolved in DCM (10 mL) and cooled to 0° C. The solution was treated with oxalyl chloride (1.2 mL, 13.8 mmol) and DMF (0.07 mL, 0.87 mmol), allowed to warm to RT, and stirred for 2 h for complete conversion to 2-methylcyclopropanecarboxylic acid chloride. The solution was cooled to 0° C. and added via syringe to a stirred solution of semicarbazide hydrochloride (1.4 g, 12.9 mmol) and NaOH (1.4 g, 34.4 mmol) in a mixture of dioxane (10 mL) and water (2.0 mL) at 0° C. The reaction mixture was allowed to warm to RT and stirred for 12 h. The organic solvent was evaporated in vacuo, and the resultant slurry was diluted with 2 M NaOH (aq) (50 mL, 100 mmol). The suspension was stirred at 100° C. for 24 h. The aqueous solution was saturated with solid NH4Cl and extracted with EtOAc (5×50 mL). The combined organics were dried (Na2SO4) and concentrated in vacuo to afford 3-(1-methylcyclopropyl)-1H-1,2,4-triazol-5(4H)-one (0.65 g, 54.3%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 11.02 (m, 2H), 1.26 (s, 3H), 0.90-0.89 (m, 2H), 0.66-0.65 (m, 2H); MS (ESI) m/z: 140.1 (M+H+).

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