Prof. Henry F. Schaefer III2
1 College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123 (China)
2 Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)
Chem. Eur. J. 2015, 21, 4153–4161
Reduction of the Pd-PEPPSI precatalyst to a Pd0 species is generally thought to be essential to drive Buchwald–Hartwig amination reactions through the well- documented Pd0/PdII catalytic cycle and little attention has been paid to other possible mechanisms. Considered here is the Pd-PEPPSI-catalyzed aryl amination of chlorobenzene with aniline. A neat reaction system was used in new experiments, from which the potentially reductive roles of the solvent and labile ligand of the PEPPSI complex in leading to Pd0 species are ruled out. Computational results demonstrate that anilido-containing PdII intermediates involving σ-bond metathesis in pathways leading to the diphenylamine product have relatively low barriers. Such pathways are more favorable energetically than the corresponding reductive elimination reactions resulting in Pd0 species and other putative routes, such as the PdII/PdIV mechanism, single electron transfer mechanism, and halide atom transfer mechanism. In some special cases, if reactants/additives are inadequate to reduce a PdII precatalyst, a PdII-involved σ-bond metathesis mechanism might be feasible to drive the Buchwald–Hartwig amination reactions.
链接：
//onlinelibrary.wiley.com/doi/10.1002/chem.201406109/abstract
