Copper- and Phosphine-Free Sonogashira Coupling Reaction Catalyzed by Polyurea-Encapsulated Palladium(II)

A polyurea-encapsulated palladium catalyst (Pd EnCat (TM) 30) was first applied to Sonogashira cross-coupling reactions in the absence of a copper salt co-catalyst and under phosphine-free conditions. This polymer-anchored homogeneous palladium catalyst efficiently catalyzed the Sonogashira reaction of various iodoarenes with terminal alkynes in H2O/MeCN, and good yields were obtained at 40 degrees after 37 h in the presence of piperidine. Moreover, this catalyst maintains its efficiency through three recycle runs.