Polymer-supported Pd(0) catalyst for copper- and ligand-free Sonogashira reactions in aqueous media

Abstract

The treatment of commercially available polymethyl methacrylate (PMMA) microspheres with palladium (Pd)Cl2 and formaldehyde, generated supported Pd(0)-PMMA with 0.79 (wt)% catalyst loading. The catalyst has been used for copper- and ligand-free Sonogashira reactions in aqueous media. It is highly reactive for the reactions of iodobenzenes with aryl acetylenes or alkyl acetylenes. The performance of the recovered catalyst had no significant difference in five cycles. The Pd leaching was detected at a very low level (2.1–9.8 ppm) for each cycle. PMMA-supported PdCl2, Pd(OAc)2, PdCO3, and PdCl2(MeCN)2 have also been tested for Sonogashira reactions.

Keywords

• aqueous reaction
• ligand-free catalysis;
• polymethyl methacrylate
• sonogashira reaction
• supported palladium catalyst