Base-Promoted Annulated Aromatization of Aryl Acetylenes with Dimethyl Sulfoxide to Access Symmetrical/Unsymmetric m-Terphenyl.

A protocol for selective and efficient synthesis of symmetrical and unsymmetrical m-terphenyls is presented among aryl acetylene and DMSO in the presence of KOH and methanol. In this reaction, two molecules of aryl acetylene contribute four carbons, and DMSO, as a dual carbon donor, provides two carbons to a new aromatic ring. This protocol can be tolerated for the electron-donating or disubstituted phenylacetylenes as well as the heterocyclic acetylene derivatives.