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

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Reaction Conditions

Reaction Steps

To a stirred mixture of 6-nitro-5,7-dichloro-1,4-dihydro-2,3-quinoxalinedione (81 mg, 0.295 mMol) in ethanol (3 mL) was added SnCl2 ·2H2O (331 mg, 1.47 mMol) in one portion. The mixture was refluxed at 80° C. (oil bath 90° C.) with stirring to 0.5 h, to form a clear solution and continually refluxed for another 0.5 h. It was then cooled to room temperature and the yellow precipitate was collected by filtration, followed by washing with cold ethanol (2×1 mL) to give 70 mg (97%) of crude title compound (contains minor impurities by NMR). Crystallization from DMSO/H2O gave 32 mg of pure title compound as bright yellow needles; mp: 342°-5° C. (dec. from 335° C.), changed color from 325° C. IR (KBr, cm-1): 3468, 3362, 3193, 1693, 1631, 1493, 1375; NMR (1H, DMSO-d6): δ5.418 (s, 2H); 6.999 (s, 1H); 11.238 (s, 1H); 11.776 (s, 1H). HRMS: calcd for C8H5N3O2Cl2 (M+) m/z: 244.9757; found 244.9769. Potency relative to DCK: 8.6%.

Provenance & Evidence