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Umpolung by N‐Heterocyclic Carbenes: Generation and Reactivity of the Elusive 2,2‐Diamino Enols (Breslow Intermediates)
Author(s) -
Berkessel Albrecht,
Elfert Silvia,
Yatham V. Reddy,
Neudörfl JörgM.,
Schlörer Nils E.,
Teles J. Henrique
Publication year - 2012
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.201205878
Subject(s) - umpolung , carbene , deprotonation , chemistry , benzoin , aldehyde , reactivity (psychology) , alkene , organic chemistry , catalysis , nucleophile , medicine , ion , alternative medicine , pathology
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.