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Cooperative Reductive Elimination: The Missing Piece in the Oxidative‐Coupling Mechanistic Puzzle
Author(s) -
FunesArdoiz Ignacio,
Maseras Feliu
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201510540
Subject(s) - reductive elimination , chemistry , isocoumarin , yield (engineering) , benzoic acid , oxidative addition , combinatorial chemistry , elimination reaction , reaction mechanism , derivative (finance) , computational chemistry , medicinal chemistry , catalysis , stereochemistry , organic chemistry , materials science , metallurgy , economics , financial economics
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 (H 2 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 CO 2 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.