5-Nitrobenzofuran-2-carboxylic acid → Ethyl 5-aminobenzofuran-2-carboxylate

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Reaction Steps

The appropriate arylcarboxylic acid is synthesized by the coupling of indole-2-carboxylic acid, benzofuran-2-carboxylic acid or benzothiophene-2-carboxylic acid with ethyl 5-amino-aryl-2-carboxylate in DMF with EDCI, and saponification of the ester. Ethyl 5-aminoindole-2-carboxylate is formed by catalytic hydrogenation of ethyl 5-nitroindole-2-carboxylate (Parmerter, S. M.; Cook, A. G.; Dixon, W. B. J. Am. Chem. Soc. 1958, 80, 4621). Ethyl 5-aminobenzothiophene-2-carboxylate can be synthesized as described in: Zambias, R. A.; Hammond, M. L. J. Syn. Commun. 1991, 21, 959. Ethyl 5-aminobenzofuran-2-carboxylate is prepared from the commercially available 5-nitrobenzofuran-2-carboxylic acid.

Provenance & Evidence