Silk−Fibroin‐Supported Palladium Catalyst for Suzuki‐Miyaura and Ullmann Coupling Reactions of Aryl Chlorides
Giorgio Rizzo, Gianluigi Albano, Teresa Sibillano, Cinzia Giannini, Roberta Musio, Fiorenzo G. Omenetto, Gianluca M. Farinola
Abstract
Abstract Recently, we have reported the preparation of a silk fibroin‐supported Palladium catalyst (Pd/SF) and its use in the Suzuki‐Miyaura cross‐coupling of aryl iodides. Since its synthetic applicability and structural features are still far from being fully explored, a deeper investigation is reported here. Pd/SF is tested as a catalyst for the Suzuki‐Miyaura and Ullmann coupling reactions of aryl chlorides, in H 2 O/EtOH solvent mixture under atmospheric conditions. Starting from the analysis of the products of the Pd/SF promoted Ullmann reactions of poly‐haloarenes, we can hypothesize the existence of catalytic pockets where monoatomic palladium species can form stable complexes with SF. To shed light on this hypothesis, Pd/SF is characterized by Wide‐Angle X‐ray Scattering (WAXS) analysis, which supports the supposition of catalytic pockets. Finally, using a computational model developed by Molecular Mechanic Energy Minimization we have estimated the dimension of the catalytic pocket of Pd/SF (about 15 Å), in good agreement with the experimental results.