Cooperative Reductive Elimination: The Missing Piece in the Oxidative‐Coupling Mechanistic Puzzle. (25th January 2016)

• Record Type: Journal Article
• Authors: Funes‐Ardoiz, Ignacio; Maseras, Feliu
• Is Part Of: Angewandte Chemie. Volume 128:Number 8(2016)
• Page Start: 2814
• Page End: 2817
• Publication Date: 2016-01-25
• Subjects: C-C-Kupplungen -- Dichtefunktionalrechnungen -- Oxidative Kupplungen -- Reaktionsmechanismen -- Reduktive Eliminierung; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201510540
• Languages: English
• ISSNs: 0044-8249

Abstract

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 (H2 O) 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.