MnBn(CO)5-Catalyzed Cascade C–H Activation/Annulation to Construct Bridged N -Heterocycles

Herein, a manganese-catalyzed synthesis of bridged heterocycles via a C–H activation/annulation cascade between azomethine imines and Morita–Baylis–Hillman adducts is described. MnBn(CO)5 serves as a highly active catalyst, exhibiting unique and remarkable capability in C–H activation for this transformation. The reaction demonstrates broad substrate scope and good functional group tolerance, providing direct access to bridged pyrazolone frameworks under operationally simple and solvent-free conditions.