Enantioselective Heck Reaction Gives Allenes

  • Author: ChemistryViews.org
  • Published: 05 December 2019
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
  • Source / Publisher: Journal of the American Chemical Society/ACS Publications
  • Associated Societies: American Chemical Society (ACS), USA
thumbnail image: Enantioselective Heck Reaction Gives Allenes

Allenes, i.e., organic molecules with two neighboring C=C bonds, can be chiral. They are useful synthetic intermediates and can be found in natural products. There are several strategies for the synthesis of chiral trisubstituted allenes. However, it is still challenging to use the well-known Heck reaction to create allenes in an enantioselective way. This is due to an unfavored β-hydride elimination at an intermediate vinyl palladium species.


Shengming Ma, Fudan University, Shanghai, China, Junliang Zhang, East China Normal University, Shanghai, and Fudan University, and colleagues have developed the first palladium-catalyzed asymmetric Heck reaction between aryl triflates and alkynes to give trisubstituted allenes (pictured). The team used di-μ-chloro-bis[2-[(dimethylamino)methyl]phenyl-C,N]dipalladium(II) as a catalyst, together with a chiral sulfinamide phosphine ligand with large aromatic substituents (a modified Xu-Phos ligand). The reaction was performed in the presence of Na3PO4 as a base in a mixture of tetrahydrofuran (THF) and water at 65 °C.


According to the team, the steric hindrance induced by the large substituents at the sulfinamide phosphine ligand allows the otherwise energetically unfavored β-hydride elimination. The desired products were obtained in moderate to high yields and with high enantioselectivities. These products could be useful in further transformations to create other chiral compounds.


 

 

Article Views: 1486

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 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


A product of ChemPubSoc Europe (16 European Chemical Societies)published by Wiley-VCH