3,4-Diaminobenzoic acid → 4-Amino-3-(1-methyl-4-nitro-2-pyrrolecarboxamido)benzoic acid

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Reaction Steps

As a further alternative, the compound of the formula (14) can also be synthesized as will be described next. For example, 1-methyl-4-nitro-2-pyrrolecarboxylic acid is reacted, by using the process disclosed in Tetrahedron, 34, 2389-2391(1978), with thionyl chloride into 1-methyl-4-nitro-2-pyrrolecarboxylic acid chloride, which is then reacted with a 3,4-diaminobenzoic acid to obtain 3-amino-4-(1-methyl-4-nitro-2-pyrrolecarboxamido)benzoic acid or 4-amino-3-(1-methyl-4-nitro-2-pyrrolecarboxamido)benzoic acid as the exemplified compound. Here, the reaction product can also be a mixture of both the benzoic acids. Methylene chloride, chloroform, DMF or the like can be used as a solvent. Other solvents are also usable as long as they do not take part in the reactions. Heating of the thus-obtained amide compound with trilfluoroacetic acid with any solvent, which do not participate in the reaction, provides 1H-2-(1-methyl-4-nitropyrrol-2-yl)benzimidazole-5-carboxylic acid. Further, 1-methyl-4-nitro-2-trichloroacetylpyrrole which is a known compound disclosed in Heterocycles, 27, 1945-1952(1988) is likewise reacted with 3,4-diaminobenzoic acid to obtain 3-amino-4-(1-methyl-4-nitro-2-pyrrolecarboxamido)-benzoic acid or 4-amino-3-(1-methyl-4-nitro-2-pyrrolecarboxamido)benzoic acid. Here, the reaction product can also be a mixture of both the benzoic acids. The reaction product can also be converted into 1H-2-(1-methyl-4-nitropyrrole-2-yl)benzimidazole-5-carboxylic acid likewise. The reaction can also be conducted similarly by using as a starting material an equivalent carboxylic acid other than 1-methylpyrrole-2-carboxylic acid.

Provenance & Evidence