Premium
Characterization of the Key Intermediates of Carbene‐Catalyzed Umpolung by NMR Spectroscopy and X‐Ray Diffraction: Breslow Intermediates, Homoenolates, and Azolium Enolates
Author(s) -
Berkessel Albrecht,
Yatham Veera Reddy,
Elfert Silvia,
Neudörfl JörgM.
Publication year - 2013
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.201303107
Subject(s) - umpolung , carbene , chemistry , catalysis , nuclear magnetic resonance spectroscopy , spectroscopy , stereochemistry , reaction intermediate , x ray crystallography , crystallography , diffraction , organic chemistry , physics , quantum mechanics , optics , nucleophile
Caught in the act : Diamino enols, diamino dienols, azolium enolates, and azolium enols are postulated intermediates of the N‐heterocyclic carbene catalyzed umpolung of aldehydes and enals. Several of these elusive reaction intermediates were generated with the saturated imidazolidin‐2‐ylidene SIPr (R=2,6‐bis(2‐propyl)phenyl) and characterized by NMR spectroscopy and X‐ray crystallography.