Palladium nanoparticles supported on natural polymer (silk fibroin): the efficient and recyclable catalyst for Heck reaction

The Heck reaction, one of the most utilized cross-coupling reactions, is the palladium-catalyzed arylation of an olefin with an aryl halide under basic conditions. It has drawn much attention due to high efficiency and simplicity. Heck methodology is attractive from a synthetic point of view because of its high chemoselectivity and mild reaction conditions along with low toxicity and cost of the reagent if, specifically, the catalyst is recycled.The Heck reaction is described as a vinylation or arylation of olefins where a large variety of olefins can be used, like derivatives of acrylates, styrenes or intramolecular double bonds [2]. The aryl halide variants developed in addition to typical arylbromides and iodides are aromatic triflates, aroyl chlorides, aryl sulfonyl chlorides, aromatic diazonium salts, aroyl anhydrides, aryl chlorides and arylsilanols [3]. TheFibroin/ Pd nanoparticles showed high catalytic activity in the heck coupling reaction. Attractive features of this protocol are high yields, simple procedure with an easywork-up, and recyclability and reusability of the catalyst.