One-Pot Synthesis of Benzo[g]indazole via Suzuki-Miyaura Coupling and Aldol Condensation Cascade Reaction

A highly efficient one-pot synthesis of benzo[g]indazole derivatives has been achieved through a cascade Suzuki–Miyaura coupling and aldol condensation reaction. Using Pd(OAc)2 and S-Phos as the catalytic system, the reaction delivered excellent yields and showed broad tolerance for various substituents on 2-formylphenylboronic acids. Moreover, this method was successfully applied to the synthesis of benzo[g]indazole-5-carbonitrile and pyrazolo[4,3-h]quinoline-5-carbonitrile derivatives by altering the coupling partners. This versatile protocol offers a straightforward and effective method for synthesizing biologically significant heterocyclic compounds.