Cooperative Reductive Elimination: The Missing Piece in the Oxidative‐Coupling Mechanistic Puzzle |
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| Authors: | Ignacio Funes‐Ardoiz Prof Feliu Maseras |
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| Affiliation: | 1. Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Tarragona, Catalonia, Spain;2. Department de Química, Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain |
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| Abstract: | The reaction between benzoic acid and methylphenylacetylene to form an isocoumarin is catalyzed by Cp*Rh(OAc)2 in the presence of Cu(OAc)2(H2O) as an oxidant and a leading example of oxidative‐coupling reactions. Its mechanism was elucidated by DFT calculations with the B97D functional. The conventional mechanism, with separate reductive‐elimination and reoxidation steps, was found to yield a naphthalene derivative as the major product by CO2 extrusion, contradicting experimental observations. The experimental result was reproduced by an alternative mechanism with a lower barrier: In this case, the copper acetate oxidant plays a key role in the reductive‐elimination step, which takes place through a transition state containing both rhodium and copper centers. This cooperative reductive‐elimination step would not be accessible with a generic oxidant, which, again, is in agreement with available experimental data. |
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| Keywords: | C− C coupling density functional calculations oxidative coupling reaction mechanisms reductive elimination |
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