Potassium Nitrate → 1-Carboxymethyl-6,7-dibromo-5-nitro-1,4-dihydro-2,3-quinoxalinedione

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Reaction Conditions

Reaction Steps

To a stirred solution of 1-carboxymethyl-6,7-dibromo-1,4-dihydroquinoxaline-2,3-dione (100 mg, 0.264 mmol) in concentrated H2SO4 (1.5 mL) at 5°-10° C., KNO3 (28 mg, 0.28 mmol) was added in one portion. The resulting dark green solution was stirred at 5°-10° C. for 30 min and at 28° C. overnight. The yellow colored suspension thus obtained was poured into ice-water (15 g) and the resulting shining yellow solid was filtered and dried under vacuum to obtain 53 mg (47%, pure by 1H NMR) 1-carboxymethyl-6,7-dibromo-5-nitro-1,4-dihydro-2,3-quinoxalinedione as a shining yellow powder; M.p. 260°-264° C. 1H NMR: δ4.91 (s, 1H), 7.98 (s, 1H). IR (KBr, cm-1): 1701, 1543, 1391, 1244. HRMS calcd for C10H5Br2N3O6 (M+) m/z 420.8546, found m/z 420.8559.

Provenance & Evidence