Regioselective Synthesis of Naphthothiophenes by Pd Catalyzed Cross-Coupling Reactions and Alkyne-Carbonyl Metathesis.

Naphthothiophenes were prepared from commercially available 2,3-dibromothiophenes in two steps by one-pot Suzuki/Sonogashira or Sonogashira/Suzuki coupling reactions, followed by intramolecular alkyne-carbonyl-metathesis reactions. The final cyclization reaction proceeds in the presence of p -toluenesulfonic acid and provides a rapid access to two series of isomeric naphthothiophenes.