Fabrication and Application of Graphene Supported Diimine-Palladium Complex Catalyst for Organic Synthesis

In this paper, a diimine palladium complex with suitable steric hindrance of isopropyl groups and electron supply provides excellent protection for palladium active centers was synthesized and anchored on graphene oxide (GO) to obtain a reusable heterogeneous catalyst (Pd-DI@GO). The XPS results confirmed the effective loading of palladium and the interaction between palladium and ligand. The ICP-AES data verified the Pd content of catalyst was 5.04 wt% and confirmed extremely small amount Pd leaching in Suzuki reaction (<1 ppm). The Pd-DI@GO can catalyze Suzuki reaction under milder conditions and afford 39 reactants with high yields (79%similar to 99%). It can achieve a yield as high as 99% with heterocyclic compound reactants which can poison the catalyst. The yields of double and triple substitutions are also impressive (70 similar to 92%). The Pd-DI@GO can catalyze the C-H direct arylation reaction efficiently, affording 22 reactants with superior yields (>85%). Notably, the Pd-DI@GO can be recycled after Suzuki reaction via filtration or centrifugation easily, presenting a yield above 90% for the 4(th) run.