Mechanism of SmI2 Reduction of 5-Bromo-6-oxo-6-phenylhexyl Methanesulfonate Studied by Spin Trapping with 2-Methyl-2-nitrosopropane

J Org Chem. 2018 Sep 7;83(17):10688-10692. doi: 10.1021/acs.joc.8b01517. Epub 2018 Aug 23.

Abstract

The radical formed by reduction of 5-bromo-6-oxo-6-phenylhexyl methanesulfonate, an α-bromoketone, with SmI2 was spin trapped with 2-methyl-2-nitrosopropane. Electron paramagnetic resonance spectra of the spin adduct and the adduct formed in the analogous reaction with selectively deuterated substrate identify the radical intermediate in this SmI2 reduction as a carbon-centered radical. This result supports the proposal that the formation of reactive Sm-enolates arises from reduction of the carbon-bromine bond rather than a ketyl radical anion.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Electron Spin Resonance Spectroscopy
  • Iodides / chemistry*
  • Nitroso Compounds / chemistry*
  • Oxidation-Reduction
  • Samarium / chemistry*
  • Spin Trapping*
  • Sulfonic Acids / chemistry*

Substances

  • Iodides
  • Nitroso Compounds
  • Sulfonic Acids
  • Samarium
  • tert-nitrosobutane
  • samarium diiodide