A Step-by-Step C-H Activation Approach to Unsymmetrical Octasubstituted Anthracenes Starting from Terephthalic Acid

We report a novel three-step approach for the synthesis of unsymmetrical octasubstituted anthracenes via rhodium(III)-catalyzed C-H activation/annulation of readily available monoalkyl terephthalates with internal alkynes. The method enables the sequential introduction of two distinct sets of substituents, providing access to a diverse library of octasubstituted anthracenes. These PAHs display tunable photophysical properties, including bright blue emission with quantum yields up to 36% and the highest values observed for unsymmetrical octaaryl- and tetraalkyl-tetraaryl derivatives. Furthermore, we demonstrate that the reactivity of these anthracenes toward photooxidation by atmospheric oxygen to form endoperoxides is strongly determined by their substitution pattern, opening up possibilities for their use as stimuli-responsive materials.