6-Nitro-2H-1,4-benzoxazin-3(4H)-one → 6-amino-3,4-dihydro-2H-1,4-benzoxazin-3-one

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To a suspension of 6-nitro-2H-1,4-benzoxazin-3(4H)-one 1 (0.5 g, 0.0026 mol) and CuCl (0.77 g, 0.0078 mol) in anhydrous methanol (25 mL), stirred at 25° C. was added potassium borohydride (0.98 g, 0.018 mol) in portions (exothermic with evolution of hydrogen gas). The reaction mixture was stirred at 25° C. for 30 min. The black precipitate formed was filtered and washed with methanol. The combined filtrate and washings was evaporated to give 6-amino-2H-benzo[b][1,4]oxazin-3(4H)-one which was purified by silica gel column chromatography using ethyl acetate. Brown solid (0.29 g, 67%). 1H NMR (400 MHz, CDCl3): δ 4.34 (s, 2H); 4.81 (s, 2H); 6.09 (dd, J=2.8, 8.4 Hz, 1H); 6.14 (d, J=2.8 Hz, 1H); 6.59 (d, J=8.4 Hz, 1H); 10.44 (s, 1H).

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