A Copper-Catalyzed Formal [3 + 2]-Cycloaddition for the Synthesis of All Different Aryl-Substituted Furans and Thiophenes.

A highly efficient formal [3 + 2]-cycloaddition was established using a copper catalyst. The resulting dihydrofurans were subjected to oxidation followed by arylations to produce tetraarylfurans. In addition, the dihydrofuran can be converted to diaryldihydrothiophene by using Lawesson's reagent. This protocol will facilitate the synthesis of all different aryl-substituted furans and thiophenes.