Lending a Helping Pyridine Arm

  • ChemPubSoc Europe Logo
  • Author: Pamela Alsabeh
  • Published Date: 23 July 2017
  • Source / Publisher: Chemistry-A European Journal/Wiley-VCH
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
thumbnail image: Lending a Helping Pyridine Arm

Related Societies

Secondary amines and imines are ubiquitous functionalities throughout organic synthesis and pharmaceutical chemistry. Amine dehydrogenation is an underdeveloped method to access such groups. N–H bond activation is a key step involved in amine dehydrogenation and is typically induced by a Lewis base. Thus, suitable metal catalysts for amine hydrogenation would benefit from a Lewis basic site as well as a labile ligand, but should also avoid an undesired Lewis acid-base pair.

Martin Albrecht, University of Bern, Switzerland, and colleagues have designed and synthesized a triazolylidene ligand containing a pendant pyridine unit suitable for both dehydrogenation and N–H bond activation. Upon coordination to iridium, a chelate-stabilized complex is formed. It facilitates dehydrogenation and the pyridine unit undergoes hydrogen bonding allowing for N–H bond cleavage. The strain caused by the five-membered ring of the ligand allows for only one of two possible pyridine units to bind to the metal.

Iridium complexes were synthesized from the ligand and iridium precursors (pictured) and characterized by both NMR and X-ray crystallography, confirming the structures. The complexes were then used successfully as catalysts for the oxidative coupling of benzylic amines under base- and oxidant-free conditions. They also catalyzed the reverse reaction, the hydrogenation of imines, making these interesting dual catalysts for related applications. Stoichiometric experiments showed the metal-ligand cooperativity of these complexes, with reactivity depending on the availability of the pendant pyridyl unit.


Article Views: 1496

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


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)and Wiley-VCH