Heck coupling of 2-bromophenylacetic acid (I) with acrylic acid (II) produces the dicarboxylic acid adduct (III). Subsequent catalytic hydrogenation of the olefinic double bond of (III) gives rise to the saturated diacid (IV). Then, Friedel-Crafts intramolecular cyclization of (IV) in hot H2SO4 affords indanone (V). Bromination of (V) in AcOH yields 2-bromo-1-oxoindan-4-ylacetic acid (VI). Esterification of (VI) is carried out via conversion to the corresponding acid chloride, followed by quenching with EtOH to provide the ethyl ester (VII). Condensation of bromo indanone (VII) with diethyl imidazole-2,4-dicarboxylate (VIII) furnishes the imidazolyl indanone (IX). Ring closure of keto ester (IX) with ammonium acetate in refluxing AcOH produces the tetracyclic compound (X). The ethyl ester groups of (X) are finally hydrolyzed under basic conditions to yield the title dicarboxylic acid.

Heck coupling of 2-bromophenylacetic acid (I) with acrylic acid (II) produces the dicarboxylic acid adduct (III). Subsequent catalytic hydrogenation of the olefinic double bond of (III) gives rise to the saturated diacid (IV). Then, Friedel-Crafts intramolecular cyclization of (IV) in hot H2SO4 affords indanone (V). Bromination of (V) in AcOH yields 2-bromo-1-oxoindan-4-ylacetic acid (VI). Esterification of (VI) is carried out via conversion to the corresponding acid chloride, followed by quenching with EtOH to provide the ethyl ester (VII). Condensation of bromo indanone (VII) with diethyl imidazole-2,4-dicarboxylate (VIII) furnishes the imidazolyl indanone (IX). Ring closure of keto ester (IX) with ammonium acetate in refluxing AcOH produces the tetracyclic compound (X). The ethyl ester groups of (X) are finally hydrolyzed under basic conditions to yield the title dicarboxylic acid.