Transient‐Ligand‐Enabled ortho ‐Arylation of Five‐Membered Heterocycles: Facile Access to Mechanochromic Materials

Reported herein is the first example of a direct arylation of heteroarenes by a transient‐ligand‐directed strategy without the need to construct and deconstruct the directing group. A wide range of heteroarenes undergoes the coupling with diverse aryl iodides to assemble a large library of highly selective and functionalized 3‐arylthiophene‐2‐carbaldehydes. This route provides an opportunity to rapidly access new mechanofluorochromic materials. Moreover, a novel strategy for mechanochromic luminogens with chromism trends of red‐ and blue‐shifts has been disclosed for the first time by facile functional‐group modifications to a common structural core.