Synthesis of π-Conjugated Molecules Based on 3,4-Dioxypyrroles via Pd-Mediated Decarboxylative Cross-Coupling

A general scheme for the synthesis of π-conjugated molecules based on 3,4-dioxypyrroles is presented. The π-conjugated molecules were synthesized via Pd-mediated decarboxylative cross-coupling using various 3,4-propylenedioxypyrrole carboxylic acids and aryl bromides, including the base-sensitive electron acceptor 4,7-dibromobenzo­[c]­[1,2,5]­thiadiazole (BTD). N-Methylpyrrolidone was used as solvent, Pd­(acac)₂ was employed as the palladium source and P­(o-tol)₃ as the ligand. The methodology was applied to 3,4-dioxypyrrole monoacids and 3,4-dioxypyrrole diacids to produce multi-ring π-conjugated systems containing phenyl, thiophenyl, BTD, and pyridinyl units. In general, the method has yielded a practical approach for the synthesis of 3,4-dioxypyrrole-based π-conjugated molecules in acceptable to high yields of 44–94%.