Synthesis of Fluorine‐Containing Multisubstituted Phenanthridines by Rhodium‐Catalyzed Alkyne [2+2+2] Cycloaddition and Tandem sp2 CH Difluoromethylenation

A highly efficient method for the synthesis of fluorine-containing multisubstituted phenanthridines through Rh-catalyzed alkyne [2+2+2] cycloaddition reactions has been developed. This method exhibits excellent functional-group compatibility. When a bromodifluoromethyl group, rather than a trifluoromethyl group, was employed in the cycloaddition reaction, more-complicated polycyclic compounds were obtained through tandem Rh-catalyzed cycloaddition/CH difluoromethylenation. This route provides convenient access to fluorine-containing polycyclic compounds.