反应详情

Diazotization of methyl 4-aminothiophene-2-carboxylate with sodium nitrite followed by treatment with dimethylamine provides methyl 4-[(dimethylamino)diazenyl]thiophene-2-carboxylate. Treatment of the ester with ammonia gave the required 4-[dimethylamino)diazenyl]thiophene-2-carboxamide (compd. No. 12). The precursor compound, methyl 4-aminothiophene-2-carboxylate is produced from the commercially available thiophene-2-carboxylic acid. The nitration of thiophene-2-carboxylic acid provides an inseparable mixture of 4-nitrothiophene-2-carboxylic acid and 5-nitrothiophene-2-carboxylic acid, which is esterified to get the corresponding esters. The nitro functionality is then reduced to amines using iron powder and the mixture separated by silica gel column chromatography to obtain methyl 4-aminothiophene-2-carboxylate.