Iridium-Catalyzed Cascade Formation of Benzofulvenes

Significance

The authors report an efficient and rapid method for the synthesis of indenes from readily available aryl ketones and diaryl alkynes. Based upon previous efforts from the Shibata ­laboratories (K. Tsuchikama et al. J. Organomet. Chem. 2008, 693, 3939) this reaction is suggested to proceed initially by an iridium alkynylation at the ortho C-H position on the arene. The resultant vinyl arene then undergoes a cationic, iridium-­induced addition to the ketone. Subsequent ­dehydration produces the desired products in moderate to good yields.