Efficient Multicomponent Strategy to Pentacyclic Pyrazole-Fused Naphtho[1,8-fg]isoquinolines through Cleavage of Two Carbon–Carbon Bonds

Multicomponent reactions of acenaphthylene-1,2-dione with diaroylmethanes and electron-rich pyrazol-5-amines have been discovered. A series of new and polyfunctionalized pentacyclic pyrazole-fused naphtho[1,8-fg]isoquinolines were regioselectively synthesized. The reactions were easy to perform simply by mixing three common reactants in AcOH. During these reaction processes, the insertion of active methylene of diaroylmethane into the sp2–sp2 C–C bond of the cyclohexa-2,5-dienone ring was readily achieved and two C–C bonds were cleaved under transition-metal-free conditions.