Samarium diiodide (DmI_2) has been successfully emolyed in a number of synthetically useful transformations since its introduction as a viable reagent by Kagan.~1 While most of the work involving SmI_2 has been of a bond-forming nature, many useful fragmentation and cleavage reactions have been forthcoming. Part 1 of this review~2 focused on cleavage and fragmentation reactions of heteroatom-heteroatom and of carbon- bonds, and provided a brief mechanistic introduction to some of the reactions facilitated by SmI_2. One type of SmI_2- promoted fragmentation reaction that has enjoyed much attention is the elimination of various functional groups situated in a positition alpha or beta to the carbonyl moiety. These include a multitude of examples of the alpha-elimination of oxygen, sulfur and other functions, each of which shall be dealt with in turn, as well as the various beta-elimination (and indeed more remote sequential elimination) type reactions. In Part 2, we shall focus on these types of reactions involving carbon-heteroatom type substrates.
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