Asymmetric Anion–π Catalysis

  • Author: Angewandte Chemie International Edition
  • Published Date: 10 November 2016
  • Source / Publisher: Angewandte Chemie International Edition/Wiley-VCH
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
thumbnail image: Asymmetric Anion–π Catalysis

The stabilization of cationic reactive intermediates such as carbocations on π-basic aromatic surfaces is quite common. However, the complementary stabilization of anionic reactive intermediates and transition states on π-acidic aromatic surfaces does not occur in nature and, quite remarkably, has also been ignored in chemistry.


The first explicit example for such anion–π catalysis was reported four years ago by Stefan Matile and colleagues, University of Geneva, Switzerland [1]. The general principle has since been applied to several reactions, including enolate, enamine, and iminium chemistry, cascade processes, as well as the first reported anion–π enzyme.


The team performed further studies and explored anion–π catalysis on the large and twisted π–acidic aromatic surfaces of perylenediimides (pictured), and observed giant quadrupole moments up to +71 Buckinghams (B), among the largest ever reported for organic molecules. Quadrupole moments perpendicular to the aromatic plane are a measure of a molecule's π acidity; in comparison, TNT has around +20 B, benzene –9 B, and hexafluorobenzene +9 B.


Moreover, these highly π-acidic surfaces have sufficient space to comfortably accommodate larger transformations and thus afford the highest enantioselectivities reported to date for asymmetric anion–π catalysis.



Reference


Correction (November 22, 2016)
Reference 1 originally misidentified the cited article.

 

Article Views: 1821

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more


CONNECT:

ChemistryViews.org on Facebook

ChemistryViews.org on Twitter ChemistryViews.org on YouTube ChemistryViews.org on LinkedIn Sign up for our free newsletter


Magazine of Chemistry Europe (16 European Chemical Societies)published by Wiley-VCH