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Is Pd II ‐Promoted σ‐Bond Metathesis Mechanism Operative for the PdPEPPSI Complex‐Catalyzed Amination of Chlorobenzene with Aniline? Experiment and Theory
Author(s) -
Wang Feiqun,
Zhu Lei,
Zhou Yunfei,
Bao Xiaoguang,
Schaefer Henry F.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201406109
Subject(s) - amination , chemistry , reductive elimination , metathesis , chlorobenzene , aryl , diphenylamine , ligand (biochemistry) , catalysis , aniline , medicinal chemistry , combinatorial chemistry , aryl halide , palladium , photochemistry , organic chemistry , polymerization , polymer , biochemistry , alkyl , receptor
Reduction of the PdPEPPSI precatalyst to a Pd 0 species is generally thought to be essential to drive Buchwald–Hartwig amination reactions through the well‐ documented Pd 0 /Pd II catalytic cycle and little attention has been paid to other possible mechanisms. Considered here is the PdPEPPSI‐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 Pd 0 species are ruled out. Computational results demonstrate that anilido‐containing Pd II 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 Pd 0 species and other putative routes, such as the Pd II /Pd IV mechanism, single electron transfer mechanism, and halide atom transfer mechanism. In some special cases, if reactants/additives are inadequate to reduce a Pd II precatalyst, a Pd II ‐involved σ‐bond metathesis mechanism might be feasible to drive the Buchwald–Hartwig amination reactions.