Oxime-palladacycle complex supported on magnetic nanoparticles: a recyclable catalyst for Suzuki-type decarbonylative cross-coupling of esters with aryl boronic acid†

Abstract

To simplify the reuse and recovery of catalysts, we have developed a magnetically separable, oxime-based palladacycle complex (Fe₃O₄@TEOS-palladacycle) and demonstrated that it is a very efficient and versatile catalyst for Suzuki-type decarbonylative cross-coupling of esters with aryl boronic acid in 2-MeTHF under refluxing conditions. The novel catalyst was synthesized using a multi-step process involving surface modification, oxime-functionalization, and palladium immobilization, and characterized by FT-IR, P-XRD, FE-SEM, TEM, EDX, TGA, VSM, XPS, and ICP-OES analysis. This protocol is advantageous due to the utilization of non-toxic, biomass-derived 2-MeTHF as a green solvent medium. The Fe₃O₄@TEOS-palladacycle was also used as an efficient catalyst for the preparation of boscalid, a significant fungicide, via a decarbonylative approach. Moreover, the solid catalyst could be recovered easily by a simple magnetic separation technique and reused five times without significant loss of its catalytic activity with negligible metal leaching. More importantly, the wide range of functional groups found to be compatible with the given reaction conditions are the main merits of this protocol.