Heck-Matsuda Reactions Catalyzed by a Hydroxyalkyl-Functionalized NHC and Palladium Acetate

The functionalized NHC obtained from salt 2 is a good ligand for palladium in the HeckMatsuda reaction of arenediazonium salts and different alkenes. The reaction is performed with low catalyst loading (0.51 mol-% of Pd) and in the absence of a base for acrylates. The protocol is also useful for the preparation of cinnamide derivatives. Compound U-77863 has been prepared successfully in good isolated yield. Cyclohexene was found to be an appropriate substrate for the reaction, giving the corresponding 1-arylcyclohexene as a single regioisomer under the studied reaction conditions. The optimal parameters of the reaction were studied by employing a design of experiments approach. Thus, the use of a small set of reactions allows the trends of the different factors to be studied. This study revealed that the best catalytic system is formed by combination of Pd(OAc)2 and salt 2 in a 1:2 ratio. This catalytic system produces better results without the use of a base.