A Dichotomy in Cross-Coupling Site Selectivity in a Dihalogenated Heteroarene: Influence of Mononuclear Pd, Pd Clusters, and Pd Nanoparticles—the Case for Exploiting Pd Catalyst Speciation
Neil W. J. Scott, Mark J. Ford, Neda Jeddi, Anthony Eyles, Lauriane Simon, Adrian C. Whitwood, Theo F. N. Tanner, Charlotte E. Willans, Ian J. S. Fairlamb
Abstract
-type clusters and nanoparticles, switch arylation site-selectivity from C2 to C4, in 2,4-dibromopyridine cross-couplings with both organoboronic acids (SMCC reactions) and Grignard reagents (Kumada-type reactions). The Pd/ligand ratio and the presence of suitable stabilizing salts were found to be critically important in switching the site-selectivity. More generally, this study provides experimental evidence that aggregated Pd catalyst species not only are catalytically competent but also alter reaction outcomes through changes in product selectivity.
Topics & Concepts
ChemistryCatalysisPalladiumHeteroatomSelectivityElectrophileCombinatorial chemistryReagentHalogenCoupling (piping)NanoparticleGenetic algorithmOrganic chemistryNanotechnologyEngineeringMaterials scienceEvolutionary biologyAlkylMechanical engineeringBiologyRing (chemistry)Catalytic Cross-Coupling ReactionsCatalytic C–H Functionalization MethodsChemical synthesis and alkaloids