Palladium nano-particles supported on agarose as efficient catalyst and bioorganic ligand for C-C bond formation via solventless Mizoroki-Heck reaction and Sonogashira-Hagihara reaction in polyethylene glycol (PEG 400)

In this study, abundant naturally occurring agarose has been used as a support and ligand for palladium nanoparticles. In the presence of this catalytic system, Mizoroki-Heck and Sonogashira-Hagihara coupling reactions were performed successfully. The catalyst exhibits high activity in Mizoroki-Heck reaction under phosphane and solvent-free conditions for the reaction of iodo- and bromoarenes with butyl acrylate and styrene. This catalytic system also showed high catalytic activity for Sonogashira-Hagihara coupling reaction of various aryl halides (I, Br, Cl) under copper and ligand-free conditions in polyethylene glycol (PEG 400) as an ecofriendly and non-poisonous media. The catalyst can be separated from the reaction mixture and reused for the similar batches of the reaction. High efficiency of the catalyst along with its recycling ability and the rather low Pd-loading which are demonstrated in both Mizoroki-Heck and Sonogashira-Hagihara reactions are the merits of the presented catalyst system. (C) 2012 Published by Elsevier B.V.