page_title: Reductions with samarium(II) iodide
section_title: History
hierarchical_section_title: Reductions with samarium(II) iodide / History
caption_attribution_description: Ball-and-stick model of the diiodopenta(THF)samarium(II) complex, [SmI2(THF)5]. X-ray crystallographic data from J. Am. Chem. Soc. (1995) 117, 8999–9002. Image generated in Accelrys DS Visualizer.
context_page_description: Reductions with samarium(II) iodide involve the conversion of various classes of organic compounds into reduced products through the action of samarium(II) iodide, a mild one-electron reducing agent.
context_section_description: In 1979, Kagan observed the reduction of a variety of organic functional groups by samarium iodide under mild conditions. Since that time, samarium iodide has been employed in a variety of contexts in organic synthesis for both functional group manipulation and carbon-carbon bond formation. 
   
  Samarium iodide is a one-electron reductant, and typically effects reduction through a series of electron transfer and proton transfer (from protic solvent) steps. Reducible functional groups include:
  α-Functionalized carbonyl compounds
  Ketones and aldehydes
  Carboxylic acids (under strongly acidic or basic conditions)
  Organic halides
  Nitro compounds
  Some examples of functionality reduced by SmI₂ are provided below.
  The reactivity of SmI₂ is significantly affected by the choice of solvent. The use of hexamethylphosphoramide (HMPA) as a co-solvent in samarium iodide reductions allows the reaction to be carried out under much milder conditions than in its absence. It has recently been investigated and determined that tripyrrolidinophosphoric acid triamide (TPPA) can be used in lieu of HMPA as an activator for SmI₂ reductions, producing faster reactions and similar yields while avoiding the use of a known carcinogen. In general, polar solvents increase the reducing properties of samarium iodide.
caption: Structure of SmI2(thf)5.[5]
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