Synthesis of Dibenzopentalenes via Pd(0)-Catalyzed Cascade Coupling of gem-Dibromo Olefins

We report a Pd-catalyzed cascade twofold Suzuki-type coupling of gem-dibromo olefins and benzene-1,2-bis-boronates to access a range of unsymmetrical dibenzopentalenes. The methodology provides exclusive access to unsymmetrical dibenzopentalenes without needing a superstoichiometric amount of substrates. This approach has been extended to the synthesis of benzopentalenes. The photophysical and electrochemical characteristics of the products were studied by using UV-vis spectroscopy and cyclic voltammetry experiments, further supported by TD-DFT studies.