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Cyclic (Aryl)(Amido)Carbenes: NHCs with Triplet‐like Reactivity
Author(s) -
Sultane Prakash R.,
Ahumada Guillermo,
JanssenMüller Daniel,
Bielawski Christopher W.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201910350
Subject(s) - electrophile , chemistry , reactivity (psychology) , aryl , singlet state , adduct , photochemistry , carbene , singlet oxygen , triplet state , medicinal chemistry , computational chemistry , molecule , organic chemistry , oxygen , catalysis , excited state , alkyl , medicine , alternative medicine , physics , pathology , nuclear physics
The synthesis and study of a library of cyclic (aryl)(amido)carbenes (CArAmCs), which represent a class of electrophilic NHCs that feature low calculated singlet‐triplet gaps (Δ E ST =19.9 kcal mol −1 ; B3LYP/def2‐TZVP) and exhibit reactivity profiles expected from triplet carbenes, are described. The electrophilic properties of the CArAmCs were quantified by analyzing their respective selenium adducts, which exhibited the largest downfield 77 Se NMR chemical shifts (up to 1645 ppm) measured for any NHC derivative known to date, as well as their Ir carbonyl complexes, from which large Tolman electronic parameter (TEP) values (up to 2064 cm −1 ) were ascertained. The CArAmCs were found to engage in reactions that are typically observed with triplet carbenes, including C−H insertions, [2+1] cycloadditions with alkenes as well as alkynes, and spontaneous oxidation upon exposure to oxygen.