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Breslow Intermediates from Aromatic N‐Heterocyclic Carbenes (Benzimidazolin‐2‐ylidenes, Thiazolin‐2‐ylidenes)
Author(s) -
Paul Mathias,
Sudkaow Panyapon,
Wessels Alina,
Schlörer Nils E.,
Neudörfl JörgM.,
Berkessel Albrecht
Publication year - 2018
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.201801676
Subject(s) - chemistry , benzoin , aldehyde , reactivity (psychology) , dimer , carbene , medicinal chemistry , stereochemistry , polymer chemistry , organic chemistry , catalysis , pathology , medicine , alternative medicine
We report the first generation and characterization of elusive Breslow intermediates derived from aromatic N‐heterocyclic carbenes (NHCs), namely benzimidazolin‐2‐ylidenes (NMR, X‐ray analysis) and thiazolin‐2‐ylidenes (NMR). In the former case, the diamino enols were generated by reaction of the free N,N‐bis(2,6‐diisopropylphenyl)‐ and N,N‐bis(mesityl)‐substituted benzimidazolin‐2‐ylidenes with aldehydes while the dimer of 3,4,5‐trimethylthiazolin‐2‐ylidene served as the starting material in the latter case. The unambiguous NMR identification of the first thiazolin‐2‐ylidene‐based Breslow intermediate rests on double 13 C labeling of both the NHC and the aldehyde component. The acyl anion reactivity was confirmed by benzoin formation with excess aldehyde.