C-C bond formation strategy through ecocatalysis: Insights from structural studies and synthetic potential

We report the elaboration of novel bio-sourced ecocatalysts for Heck and Suzuki cross-coupling reactions. Ecocatalysis is based on the recycling of metals issued from phytoremediation or rehabilitation, and an innovative chemical valorization of the subsequent biomass in the field of catalysis. Here, we describe the efficient palladium accumulation by plants (Brassica juncea, Lolium multiflorum) via rhizofiltration. Taking advantage of the remarkable ability of the selected plants to accumulate Pd(II) species into their roots, these latter can be directly used for the preparation of ecocatalysts, called Eco-Pd (R). The formed Eco-Pd (R) catalysts are thoroughly characterized via ICP-MS, XRD, XPS, TEM, SEM in order to elucidate the chemical composition and morphology of the formed materials. Significant differences to conventional Pd-based catalysts such as palladium(II) chloride can principally be related to a particular Lewis acid behavior of the Eco-Pd (R) catalysts. Finally, the obtained Eco-Pd (R) appear as highly active catalysts in Heck and Suzuki cross-coupling reactions necessitating considerably lower Pd quantity compared to precedently reported bio-sourced palladium containing catalysts. (C) 2015 Elsevier B.V. All rights reserved.