Pd immobilized on EDTA-modified cellulose: synthesis, characterization, and catalytic application in inter- and intramolecular Heck reactions and Larock reactions

Pd immobilized on EDTA-modified cellulose (Pd@Cell-EDTA) was successfully prepared through sequential procedure of esterification of cellulose with ethylenediaminetetraacetic acid (EDTA) dianhydride and metathesis with PdCl2. The as-synthesized Pd@Cell-EDTA was well characterized by ICP-AES, FTIR, SEM, EDX, elemental mapping, TEM, and XPS tools. TEM revealed that spherical Pd nanoparticles were homogeneously dispersed on the surface of Cell-EDTA with a narrow size of about 5 nm and the Pd content in fresh Pd@Cell-EDTA catalyst was determined to be 0.10 mmol/g by ICP-AES. Due to the regulation of multidentate sites of EDTA, the immobilized Pd exhibited high catalytic activity in the inter- and intramolecular Heck reactions and heteroannulation Larock reactions to afford the desired products in excellent yields (66-97%). The catalyst recycling experiments for the model Heck reaction showed that the catalyst can be reused at least four consecutive runs with a slight drop in its catalytic activity. This catalyst proved its practical applications in the form of carbon-carbon and carbon-heteroatom bond for synthesis of diverse arylated alkenes and indoles. [GRAPHICS] .