Samarium diiodide is one of the most important reducing agents available to synthetic organic chemists. The lanthanide(II) reagent acts by single-electron transfer to organic substrates leading to the formation of both radical and/or anionic intermediates. The power of the reagent arises from its versatility - samarium diiodide can be used in processes ranging from functional group conversions to elaborate carbon-carbon bond-forming cyclization sequences that result in a dramatic increase in molecular complexity. In addition, reactions involving samarium diiodide often show high...