Synthetic and Mechanistic Studies into the Reductive Functionalization of Nitro Compounds Catalyzed by an Iron(salen) Complex

Emily Pocock, Martin Diefenbach, Thomas M. Hood, Michael Nunn, Emma Richards, Vera Krewald, Ruth L. Webster

Research output: Contribution to journalArticlepeer-review

4 Citations (SciVal)

Abstract

We report on the use of a simple, bench-stable [Fe(salen)2]-μ-oxo precatalyst in the reduction of nitro compounds. The reaction proceeds at room temperature across a range of substrates, including nitro aromatics and aliphatics. By changing the reducing agent from pinacol borane (HBpin) to phenyl silane (H3SiPh), we can chemoselectively reduce nitro compounds while retaining carbonyl functionality. Our mechanistic studies, which include kinetics, electron paramagnetic resonance (EPR), mass spectrometry, and quantum chemistry, indicate the presence of a nitroso intermediate and the generation of an on-cycle iron hydride as a key catalytic intermediate. Based on this mechanistic insight, we were able to extend the chemistry to hydroamination and identified a simple substrate feature (alkene lowest unoccupied molecular orbital (LUMO) energy) that could be used to predict which alkenes would result in productive catalysis.

Original languageEnglish
Pages (from-to)19839-19851
Number of pages13
JournalJournal of the American Chemical Society
Volume146
Issue number29
Early online date12 Jul 2024
DOIs
Publication statusPublished - 12 Jul 2024

Acknowledgements

Calculations for this research were conducted on the Lichtenberg high-performance computer of the TU Darmstadt. The authors would like to thank Professor Ian Fairlamb and Karl Heaton (University of York) for instrument time and assistance with LIFDI-MS measurements. We also appreciate assistance from Dr. John Lowe and Dr. Kathryn Proctor (Core Research Facility, University of Bath) with DOSY NMR and MS analyses, respectively. Professor Simon Lewis is acknowledged for lab-based support (EP).

Funding

The EPSRC (R.L.W.), Leverhulme Trust (R.L.W., T.M.H., M.D., V.K.), and Astra Zeneca (E.P.) are thanked for funding. Cei Provis-Evans is thanked for initial studies into the reduction of nitromethane, 1-methoxy-3-nitrobenzene, 2-nitropropane, and 1-nitropentane.

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry

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