López, J.A.; Cabo, D.A.; Palma, P.; Cámpora, J. A Comparison of β–Phenyl Elimination in Nickel and Palladium Alkyl Complexes: A Potentially Relevant Process in the Mizoroki–Heck Reaction. Inorganics2024, 12, 89.
López, J.A.; Cabo, D.A.; Palma, P.; Cámpora, J. A Comparison of β–Phenyl Elimination in Nickel and Palladium Alkyl Complexes: A Potentially Relevant Process in the Mizoroki–Heck Reaction. Inorganics 2024, 12, 89.
López, J.A.; Cabo, D.A.; Palma, P.; Cámpora, J. A Comparison of β–Phenyl Elimination in Nickel and Palladium Alkyl Complexes: A Potentially Relevant Process in the Mizoroki–Heck Reaction. Inorganics2024, 12, 89.
López, J.A.; Cabo, D.A.; Palma, P.; Cámpora, J. A Comparison of β–Phenyl Elimination in Nickel and Palladium Alkyl Complexes: A Potentially Relevant Process in the Mizoroki–Heck Reaction. Inorganics 2024, 12, 89.
Abstract
There is currently much interest in avoiding precious metals in Catalysis. The devel-opment of nickel catalysts to replace palladium in the Mizoroki-Heck reaction is a relevant case in this line of research since both elements share many chemical features. This contri-bution focuses on -Phenyl elimination in alkylnickel complexes. This is the microscopic reverse of olefin insertion (or carbometallation), a fundamental step of the Heck cycle that is usually considered irreversible and selectivity-determining. However, the potential reversibil-ity of carbometallation is generally concealed by the facile beta-hydrogen elimination that follows. Where -hydrogen elimination is hindered, beta-aryl elimination may ensue. We have previously shown that cationic 2-methyl-2-phenylpropyl (neophyl) palladium com-plexes supported by bidentate ligands experience -Ph elimination, which can be seen as an example of olefin de-insertion. In this contribution, we report that -phenyl elimination can also occur in their nickel analogs, in which case fast hydrolyses of the resulting phenyl product can follow the reaction. We investigated the mechanism of these processes and compared their feasibility for nickel and palladium catalysts using DFT calculations. These results are relevant information for the design of nickel-based catalysts for the Heck reac-tion.
Chemistry and Materials Science, Organic Chemistry
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
