3 years ago

Evidence of a Sole Oxygen Atom Transfer Agent in Asymmetric Epoxidations with Fe-pdp Catalysts

Evidence of a Sole Oxygen Atom Transfer Agent in Asymmetric Epoxidations with Fe-pdp Catalysts
Miquel Costas, Olaf Cussó, Joan Serrano-Plana
Iron complexes with chiral tetradentate ligands based on the pdp scaffold (pdp = N,N′-bis(2-pyridylmethyl)-2,2′-bipyrrolidine) are efficient and versatile catalysts for the highly enantioselective epoxidation of a wide range of olefins. The nature of the species responsible for oxygen atom transfer to the olefin in these reactions is under debate. In order to investigate this question, the enantioselectivity of the epoxidation reaction has been used as a mechanistic probe. The enantioselectivities obtained under different reaction conditions for two iron catalysts (S,S)-[Fe(CF3SO3)2(Me2Npdp)] ((S,S)Me2N1Fe) and (S,S)-[Fe(CF3SO3)2(dMMpdp)] ((S,S)dMM1Fe) have been analyzed. Reactions were performed with a series of peracids, and enantioselectivities of these reactions were compared with those obtained by combining peroxides and carboxylic acids. This analysis provides conclusive experimental evidence that the same oxidant is responsible for the asymmetric epoxidation reaction in both scenarios. The study also provides insight into the nature of the oxygen atom transfer species, as well as its mechanism of formation, offering a rational guide for defining catalytic systems with more versatile structures and improved selectivity.

Publisher URL: http://dx.doi.org/10.1021/acscatal.7b01184

DOI: 10.1021/acscatal.7b01184

You might also like
Never Miss Important Research

Researcher is an app designed by academics, for academics. Create a personalised feed in two minutes.
Choose from over 15,000 academics journals covering ten research areas then let Researcher deliver you papers tailored to your interests each day.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.