5-Nitrobenzofuran-2-carboxylic acid → Ethyl 5-aminobenzofuran-2-carboxylate
Reaction equation
[NH2:1][C:2]1[CH:3]=[CH:4][C:5]2S[C:8]([C:10]([O:12][CH2:13][CH3:14])=[O:11])=[CH:7][C:6]=2[CH:15]=1.[N+](C1C=CC2OC(C(O)=O)=CC=2C=1)([O-])=[O:17]>>[NH2:1][C:2]1[CH:3]=[CH:4][C:5]2[O:17][C:8]([C:10]([O:12][CH2:13][CH3:14])=[O:11])=[CH:7][C:6]=2[CH:15]=1Participants
3
Procedure
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.