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

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Reaction Conditions

Reaction Steps

To a stirred mixture of 6-nitro-7-bromo-1,4-dihydro-2,3-quinoxalinedione (87 mg, 0.30 mMol) in ethanol (3 mL) and DMSO (0.5 mL) was added SnCl2.2H2O (343 mg, 1.50 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 which was refluxed for another 1 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 50 mg (67%) of crude title compound (contains minor impurities by NMR). Crystallization from DMSO/H2O gave 21 mg of pure as bright yellow needles, mp: >300° C. (dec. from 315° C.), changed color from 300° C. NMR (1H, DMSO-d6): d 5.257 (s, 2H); 6.558 (s, 1H); 7.087 (s, 11t); 11.599 (s, 1H); 11.792 (s, 1H). HRMS: calcd for C8H6N3O2Br (M+) m/z: 254.9642; found 254.9630. Potency relative to DCK: 7.1%.

Provenance & Evidence