Palladium-Catalyzed Radical Cascade Iododifluoromethylation/Cyclization of 1,6-Enynes with Ethyl Difluoroiodoacetate

A novel and convenient Pd-catalyzed
radical cascade iododifluoromethylation/cyclization
of 1,6-enynes with ethyl difluoroiodoacetate is demonstrated. The
proposed transformation presents high stereoselectivity under mild
and facile reaction conditions, thereby allowing an efficient access
to a variety of iodine-containing difluoromethylated pyrrolidines.
A possible radical pathway for the transformation is proposed on the
basis of the results of control experiments and relevant literature
reviews.