Different Oxidative Addition Mechanisms for 12- and 14-Electron Palladium(0) Explain Ligand-Controlled Divergent Site Selectivity

ABSTRACT: In cross-coupling reactions, dihaloheteroarenes are usually most reactive at C─halide bonds adjacent to a heteroatom. This selectivity has been previously rationalized. However, no mechanistic explanation exists for anomalous reports in which specific ligands effect inverted selectivity with dihalopyridines and -pyridazines. Here we provide evidence that these ligands uniquely promote oxidative addition at 12e− Pd(0). Computations indicate that 12e− and 14e− Pd(0) can favor different mechanisms for oxidative addition due to differences in their HOMO symmetries. These mechanisms are shown to lead to different site preferences, where 12e− Pd(0) can favor oxidative addition at an atypical site distal to nitrogen. Graphical Abstract

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PROVIDER: S-EPMC10438894 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature