Stannous chloride dihydrate → 5-Amino-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione

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Reaction Conditions

Reaction Steps

To a stirred mixture of 5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione (110 mg, 0.40 mMol) in ethanol (6 mL) was added SnCl2.2H2O (448 mg, 2.0 mMol) in one portion. The mixture was refluxed at 80° C. (oil bath 90° C.) with stirring for 1 h to form a clear solution and continually refluxed for another 3 h. The mixture was then cooled to room temperature and the yellow precipitate was collected by filtration and washed with cold ethanol (2×1 mL) to give 61 mg (62%) of crude title compound (contains minor impurities by NMR). Crystallization from DMSO/H2O gave 43 mg of pure title compound as bright yellow needles, mp>350° C. (dec.), changed color from 320° C. IR (KBr, cm-1): 3468; 3389; 3057; 1695; 1636; 1596; 1397. NMR (1H, DMSO-d6): δ5.935 (s, 2H); 6.595 (s, 1H); 11.317 (s, 1H); 11.868 (s, 1H). Purity >98.95% by HPLC. HRMS: calcd for C8H5N3O2Br2 (M+) m/z: 244.9757; found 244.9740. Potency relative to DCK: 323%.

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