Oxalic acid dihydrate → 7-Fluoro-5-trifluoromethyl-1,4-dihydro-2,3-quinoxalinedione

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Reaction Steps

A mixture of 2,3-diamino-5-fluorobenzotrifluoride (148 mg, 0.76 mmol) and oxalic acid dihydrate (96 mg, 0.76 mmol, used as received) in 4N HCl (2 mL) was refluxed at 120°-5° C. for 3 h, then cooled to room temperature. The mixture was centrifuged and the liquid layer was removed. The yellow solid was washed by cold water (2×2 mL), collected by filtration, and dried at 60° C. for 2 h, affording 120 mg of crude title compound (64%) as a yellow powder. The crude product was dissolved in 1N NaOH (5 mL) and filtered. The filtrate was acidified to pH=6, affording 110 mg of pure title compound as a yellow powder. Mp: 300°-2° C. IR (KBr, cm-1): 3408, 3122, 1754, 1721, 1621, 1492. 1H NMR (DMSO-d6): δ 7.178 (dd, 1H, J1 =2.7 Hz, J2 =8.7 Hz), 7.359 (dd, 1H, J1 =2.7 Hz, J2 =8.7 Hz); 11.270 (s, 1H); 12.237 (s, 1H). HRMS: calcd for C9H4N2O2 (M+) m/z: 248.0208; found: 248.0220.

Provenance & Evidence