Bis(pyrazolyl)methane Copper Complexes as Robust and Efficient Catalysts for Sonogashira Couplings
European Journal of Organic Chemistry, 2015, 34, 7475–7483
A series of bis(pyrazolyl)methane copper complexes were found to catalyze a fast palladium-free Sonogashira coupling reaction of several iodoarenes with terminal alkynes such as phenylacetylene, propargyl benzyl ether, and (tert-butyl-dimethyl)silylacetylene. These reactions proceed with CuCl2·2H2O (10 mol-%) under aerobic conditions and the corresponding chelate ligand (10 mol-%), with its tailored facial coordination mode, is crucial for the success of the reaction. The coupling can also be carried out in water with liquid aryl halides and a phase-transfer catalyst.