Catalytic Radical-Triggered Annulation/Iododifluoromethylation of Enynones for the Stereospecific Synthesis of 1-Indenones.

A new Pd(II)-catalyzed annulation/iododifluoromethylation of enynones has been developed for the synthesis of versatile 1-indanones with moderate to good yields (26 examples). The present strategy enabled the concomitant incorporation of two important difluoroalkyl and iodo functionalities into 1-indenone skeletons with ( E )-stereoselectivity. The mechanistic pathway was proposed, consisting of the difluoroalkyl radical-triggered α,β-conjugated addition/5- exo -dig cyclization/metal radical cross-coupling/reductive elimination cascade.