3,4-Dimethoxy-6-nitrobenzamide → 2-Amino-4,5-dimethoxybenzamide

Beteiligte Stoffe

Reaktionsschritte

NaBH4 (400 mg) was added with stirring over 4 hours to a solution of 4,5-dimethoxy-2-nitrobenzamide 2 (1.58 g; 7 mmol) in MeOH containing catalytic amount of CuSO4. The reaction mixture was poured into ice-water (200 mL) with stirring to give 4,5-dimethoxy-2-aminobenzamide 3 which was directly refluxed with HCOOH (20 mL) for 5 hours. After removal of solvent, the residue was recrystallized from DMF to give pure crystals 4 (1.18 g; 81.5%). m.p. 295.0-297.0° C.; 1H NMR (DMSO-d6): δ 12.03 (br, s, 1H, —NH), 7.99 (s, 1H, 2-H), 7.42 (s, 1H, 5-H), 7.11 (s, 1H, 8-H), 3.88, 3.85 (s, s, 6H, —OCH3); IR(KBr)υmax: 3015, 2840, 1648, 1504, 1261, 1070 cm−1; GC/MS m/z 206(M+, 100), 191(M+ —CH3, 31.5), 163(16.7), 120(15.2).

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