Methane → 3-Nitro-(quinoxalinylamino)benzoic acid

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A mixture of 5-aminoquinoxaline (1.0 g, 6.89 mmol), 2-bromo-3-nitrobenzoic acid (4.0 g, 13.78 mmol), Cu/CuI (catalytic) and N-ethylmorpholine (5 mL) in isopropanol (5 mL) was heated at 65-70° C. overnight. The mixture was then dissolved in aqueous ammonia, treated with charcoal/Celite, and filtered. The filtrate was acidified with conc. HCl, and the resulting precipitate was collected while the mixture was still warm and washed with water (to remove unreacted 2-bromo-3-nitrobenzoic acid). It was then dried and chromatographed on silica gel, eluting with CH2Cl2/MeOH (19:1), to give 3-nitro-(quinoxalinylamino)benzoic acid (0.9 g, 42%): mp (MeOH) 232-237° C.; 1H NMR [(CD3)2SO] δ 6.92-6.97 (m, 1 H, ArH), 7.30 (t, J=8.0 Hz, 1 H, ArH), 7.62-7.66 (m, 2 H, 2xArH), 8.23 (dd, J=8.2, 1.6 Hz, 1 H, ArH), 8.29 (dd, J=7.8, 1.6 Hz, 1 H, ArH), 8.97 (d, J=1.7 Hz, 1 H, H-2′ or H-3′), 9.03 (d, J=1.9 Hz, 1 H, H-2′ or H-3′), 10.73 (br s, 1 H, NH), 13.8 (br s, 1 H, CO2H).

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