5-Nitroisophthalic acid (I) is converted into the dibenzyl ester (II) via activation with SOCl2. After nitro group reduction in (II), the resultant amine (III) is coupled with N-Boc-L-2-fluorophenylalanine (IV) by means of PyBrOP and DIEA to furnish amide (V). Subsequent acidic cleavage of the N-Boc protecting group of (V) provides amine (VI). (1)

Thermal dehydration of benzimidazole-5,6-dicarboxylic acid (VII) provides the cyclic anhydride (VIII). Subsequent condensation of (VIII) with amine (VI) leads to the amido-acid (IX), which is further coupled to cycloheptylmethylamine (X), yielding the benzimidazole dicarboxamide (XI). Finally, catalytic hydrogenolysis of the benzyl ester groups of (XI) affords the target isophthalic acid derivative. (1,2)

Thermal dehydration of benzimidazole-5,6-dicarboxylic acid (VII) provides the cyclic anhydride (VIII). Subsequent condensation of (VIII) with amine (VI) leads to the amido-acid (IX), which is further coupled to cycloheptylmethylamine (X), yielding the benzimidazole dicarboxamide (XI). Finally, catalytic hydrogenolysis of the benzyl ester groups of (XI) affords the target isophthalic acid derivative. (1,2)