Communication

Umpolung by N-Heterocyclic Carbenes: Generation and Reactivity of the Elusive 2,2-Diamino Enols (Breslow Intermediates)†

  1. Prof. Dr. Albrecht Berkessel1,*,
  2. Silvia Elfert1,
  3. V. Reddy Yatham1,
  4. Dr. Jörg-M. Neudörfl1,
  5. Dr. Nils E. Schlörer1,
  6. Dr. J. Henrique Teles2

Article first published online: 18 OCT 2012

DOI: 10.1002/anie.201205878

Issue

Angewandte Chemie International Edition

Angewandte Chemie International Edition

Volume 51, Issue 49, pages 12370–12374, December 3, 2012

Additional Information

How to Cite

Berkessel, A., Elfert, S., Yatham, V. R., Neudörfl, J.-M., Schlörer, N. E. and Teles, J. H. (2012), Umpolung by N-Heterocyclic Carbenes: Generation and Reactivity of the Elusive 2,2-Diamino Enols (Breslow Intermediates) . Angew. Chem. Int. Ed., 51: 12370–12374. doi: 10.1002/anie.201205878

Author Information

  1. 1

    Cologne University, Department of Chemistry, Greinstrasse 4, 50939 Cologne (Germany) http://www.berkessel.de

  2. 2

    BASF SE, GCS/X-M311, 67056 Ludwigshafen (Germany)

*Cologne University, Department of Chemistry, Greinstrasse 4, 50939 Cologne (Germany) http://www.berkessel.de

  1. †

    Support by the Fonds der Chemischen Industrie and by BASF SE is gratefully acknowledged. We thank Felix Klauck for providing samples of 13C-labeled 2,4-bis(trifluoromethyl)benzaldehyde.

Publication History

  1. Issue published online: 28 NOV 2012
  2. Article first published online: 18 OCT 2012
  3. Manuscript Revised: 31 AUG 2012
  4. Manuscript Received: 23 JUL 2012

Funded by

  • Fonds der Chemischen Industrie
  • BASF

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Keywords:

  • Breslow intermediates;
  • carbenes;
  • NMR spectroscopy;
  • reaction mechanisms;
  • umpolung
Thumbnail image of graphical abstract

54 years later: Saturated imidazolidin-2-ylidenes react with aldehydes to smoothly produce the elusive 2,2-diamino enols A (“Breslow intermediates”, first postulated in 1958) of carbene-catalyzed umpolung reactions. The 2,2-diamino enols A react with additional aldehyde in a cross-benzoin reaction. The methylated Breslow intermediates B are accessible by deprotonation of methoxymethyl azolium salts.

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