Base-Catalyzed and Solvent-Dependent Cascade Reaction in the Regioselective Synthesis of Novel Fused Polycycles

A novel base‐catalyzed cascade reaction induced by Knoevenegal condensation that can regioselectively generate cyanoflavanones and heavily fused polycycles with intensive fluorescence and high quantum yields is reported. The reaction is solvent‐dependent, low‐polarity solvents promote the formation of polycycles while high‐polarity solvents favor the conversion to cyanoflavanones. A possible mechanism for such serial transformations is proposed.