Methyl 5-nitro-1-benzothiophene-2-carboxylate → Methyl 5-amino-1-benzothiophene-2-carboxylate

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Reaction Steps

To a solution of 5-nitro-benzo[b]thiophene-2-carboxylic acid methyl ester [15] (130 mg, 0.548 mmol) in methanol (30 mL) was added 5% palladium on carbon (20 mg) and the mixture was stirred under 1 atm H2 for 2 h. The mixture was filtered through celite and the filtrate evaporated. The residue was passed through a silica column to afford 5-amino-benzo[b]thiophene-2-carboxylic acid methyl ester as a pale yellow solid (94 mg, 83%), single spot at Rf 0.75 (95:5 dichloromethane:methanol). 1H NMR (CDCl3): δ 7.86 (1H, s), 7.61 (1H, d, J=8.7 Hz), 7.11 (1H, d, J=2.2 Hz), 6.88(1H, dd, J=8.7, 2.5 Hz), 3.91 (3H, s), 3.76 (2H, s, N—H2) [16].

Provenance & Evidence