[Br:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[CH:13]=[CH:12][C:11]([Br:14])=[CH:10][C:9]=2[N+:15]([O-])=O)=[C:4]([N+:18]([O-])=O)[CH:3]=1.Cl.[Sn].[OH-].[Na+]>C(O)C>[Br:1][C:2]1[CH:3]=[C:4]([NH2:18])[C:5]([C:8]2[C:9]([NH2:15])=[CH:10][C:11]([Br:14])=[CH:12][CH:13]=2)=[CH:6][CH:7]=1To a solution of 15 (11.0 g, 27.4 mmol) in 135 mL of absolute ethanol was added 32% w/w aqueous HCl (78.0 mL). Tin powder (13.0 g, 108.5 mmol) was then added in portions over 10 min, and the reaction mixture was heated to reflux at 100° C. for 2 h. After cooling, the mixture was poured into ice water (400 mL) and then made alkaline with 20% w/w aqueous NaOH solution until the pH was 9.0. The product was next extracted with diethyl ether and the organic layer was washed with brine, dried over anhydrous Na2SO4, filtered, and then evaporated to dryness to give pure product as light-brown crystals that could be used without further purification (8.6 g, 92%). 1H NMR (CDCl3): δ 6.92 (6H, s), 3.78 (4H, br s, NH2) ppm; 13C NMR (CDCl3): δ 118.2, 121.9, 122.1, 122.8, 132.4, 145.3 ppm; m.p. 118-119° C.
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