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Mechanistic Studies on the Insertion of Carbonyl Substrates into Cu‐H: Different Rate‐Limiting Steps as a Function of Electrophilicity
Author(s) -
Tran Ba L.,
Neisen Benjamin D.,
Speelman Amy L.,
Gunasekara Thilina,
Wiedner Eric S.,
Bullock R. Morris
Publication year - 2020
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.201916406
Subject(s) - electrophile , chemistry , amide , ketone , aldehyde , monomer , dimer , hydride , stereochemistry , polymer chemistry , medicinal chemistry , photochemistry , organic chemistry , metal , polymer , catalysis
We report mechanistic studies on the insertion reactions of [(NHC)Cu(μ‐H)] 2 complexes with carbonyl substrates by UV‐vis and 1 H NMR spectroscopic kinetic studies, H/D isotopic labelling, and X‐ray crystallography. The results of these comprehensive studies show that the insertion of Cu‐H with an aldehyde, ketone, activated ester/amide, and unactivated amide consist of two different rate limiting steps: the formation of Cu‐H monomer from Cu‐H dimer for more electrophilic substrates, and hydride transfer from a transient Cu‐H monomer for less electrophilic substrates. We also report spectroscopic and crystallographic characterization of rare Cu‐hemiacetalate and Cu‐hemiaminalate moieties from the insertion of an ester or amide into the Cu−H bond.