Enantioselective Carbene-Catalyzed Annulations

  • Author: ChemistryViews
  • Published: 16 July 2013
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
  • Source / Publisher: Journal of the American Chemical Society/ACS Publications
thumbnail image: Enantioselective Carbene-Catalyzed Annulations

The majority of catalytic methods for the stereoselective formation of new C–C and C–heteroatom bonds involve a single activation mode, such as Lewis base or acid catalysis. N-Heterocyclic carbenes (NHCs) are versatile Lewis bases that catalyze a variety of bond-forming processes, including formal  [m+n] cycloadditions. One drawback of these formal cycloadditions is that the electrophilic substrates are limited to reactive C=X π systems, such as aldehydes and imines. The use of a second mode of activation to produce a more reactive electrophile in situ, is one strategy to address this problem.

Karl Scheidt and co-workers, Northwestern University, USA, combined two distinct Lewis base activation modes to achieve an enantioselective organocatalytic formal [4+3] heterocycloaddition. This dual activation strategy involved the formation of two transient species, a nucleophilic NHC homoenolate and an electrophilic o-quinone methide, thus expanding the scope of the electrophile beyond C=X π systems.

They used this method to synthesize 2-benzoxopinones, which are found in natural products and as the core of many biologically active small molecules.

Article Views: 3478

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 and consult our permission guidance prior to making your request

Follow on Facebook Follow on Twitter Follow on YouTube Follow on LinkedIn Follow on Instagram RSS Sign up for newsletters

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