Highly Electron-Donating 3,3′-Diaryl-1,1′-bi(isobenzofuran)s Synthesized by Photochemical Exocyclic [2 + 2 + 2] Cycloaddition

Facile photochemical exocyclic [2 + 2 + 2] cycloaddition produced a series of electron-donating 1,1′-bi(isobenzofuran)s having various aryl groups at the 3,3′ positions. The 1,1′-bi(isobenzofuran) skeleton with a highly coplanar structure is a useful building unit to construct the narrow bandgap π-conjugated systems with low oxidation potentials.