Cu/Pd-Catalyzed Cascade Reactions of Cyclic Diaryliodoniums and Alkynes - Access to Fluorenes with Conjugate Enynes/Dienes

Unlike the widely studied linear diaryliodoniums as electrophilic arylating reagents, cyclic diaryliodoniums have the potential to initiate dual arylations with atom and step economy. In our current work, cascade reactions of cyclic diaryliodoniums and two equivalent alkynes have been successfully achieved under mild conditions, catalyzed by CuI/PdCl2(PPh3)(2). The transformation could also be realized in a stepwise way with two different alkynes or with one alkyne and one alkene. The reaction enables a rapid access to a variety of complex fluorenes containing conjugate enyne and diene fragments.