Cyanide-Catalyzed Rearrangement Gives δ-Lactones

  • Author: ChemistryViews.org
  • Published: 24 January 2021
  • Copyright: Wiley-VCH GmbH
  • Associated Societies: American Chemical Society (ACS), USA
thumbnail image: Cyanide-Catalyzed Rearrangement Gives δ-Lactones

Lactones, i.e., cyclic carboxylic esters, are found in many natural products and biologically active compounds. δ-Lactones, for example, are common structural motifs. They can be synthesized, e.g., by the intramolecular esterification of δ-hydroxy acids or via a Baeyer–Villiger oxidation.


David Kieslich and Jens Christoffers, University of Oldenburg, Germany, have developed an approach for the transformation of α-hydroxy-β-oxoesters to δ-lactones with an additional ester group in the δ-position (pictured). The team originally attempted an etherification of an α-hydroxy-β-oxoester in the presence of a base and ammonium iodide. This reaction was unsuccessful, but the corresponding δ-lactone was isolated from the reaction mixture with a yield of 17 %. The researchers then optimized the reaction conditions and found that with KCN as a catalyst and boiling toluene as the solvent, δ-lactone yields up to 99 % can be achieved.


The α-hydroxy-β-oxoesters can be prepared by a cerium-catalyzed aerobic oxidation of β-oxoesters. This easy accessibility of the starting materials is an advantage of the developed δ-lactone synthesis. According to the researchers, the reaction proceeds via a retro-Dieckmann reaction that opens the five-ring, followed by a lactonization to give the desired products.


 

 

Article Views: 806

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

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