Conformationally Stable [4]Helicenes

  • Author: Angewandte Chemie International Edition
  • Published Date: 25 February 2020
  • Source / Publisher: Angewandte Chemie International Edition/Wiley-VCH
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
thumbnail image: Conformationally Stable [4]Helicenes

Helicenes are polyaromatic organic molecules that adopt a corkscrew-like conformation. For this reason, there are two possible enantiomeric forms of each structure. In small helicenes, such as [4]helicenes, both enantiomers easily interconvert. However, this racemization can be avoided with suitable substituents at the "inner" positions.

Manuel Alcarazo, University of Göttingen, Germany, and colleagues have performed the first highly enantioselective synthesis of 1,12‐disubstituted [4]carbohelicenes. The team used various aromatically substituted alkynes (pictured above) as substrates and performed an intramolecular hydroarylation using gold catalysts (pictured below) to prepare a range of [4]helicenes in enantiopure form. The catalysts are based on an α-cationic phosphine which contains a TADDOL unit as a chiral inductor (TADDOL=α,α,α,α‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanol).

The absolute stereochemistry of the prepared structures was determined by X‐ray crystallography. The products could have applications as functional materials with useful electrooptical properties.




Article Views: 866

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

Bookmark and Share

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

CONNECT: on Facebook on Twitter on YouTube on LinkedIn Sign up for our free newsletter

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