Friedel-Crafts Type Reaction of Chlorothiophenes with Aromatic Compounds and Its Application to the Syntheses of Aryl-and Oligothiophenes

Chlorothiophenes react with active aromatic compounds in the presence of AlCl3 under mild conditions, yielding the corresponding arylthiophenes. Similarly, chlorinated bi-and terthiophenes are produced as the main products in the AlCl3-catalyzed self-condensation of the chlorothiophenes. The reactions are discussed in terms of an ionic mechanism involving the thiophenium ions produced by the protonation of the chlorothiophenes. Versatility of the products for the syntheses of arylthiophenes, mixed thiophene-arene oligomers, and oligothiophenes is also demonstrated