Efficient Synthesis of Thiophene-Based Polycyclic Aromatic Compounds

Significance

An efficient and high-yielding synthesis of thiophene-based polycyclic aromatic compounds is reported. The one-pot Diels-Alder cycloaddition and subsequent decarbonylation generates a dithiophene-substituted benzene. After the reactive α-position of thiophene was brominated, an iron-catalyzed oxidative cyclization yields the fused aromatic molecules. Notably, thiophene polymerization was not observed under the oxidative cyclization conditions. Further elaboration to generate helicenes is achieved by repeating the procedure after Pd-catalyzed bromo­thiophene-alkyne coupling providing a new bisalkyne.