Samarium metal in organic synthesis

Recently organolanthanides have been widely employed as useful reagents in organic synthesis. Since the pioneering studies by Kagan and his co-workers demonstrated the effectiveness of samarium diiodide as a strong one-electron transfer reducing agent, the utility of this reagent in organic synthesis has been dramatically documented. There is increasing attention to performing synthetic transformation by direct reaction of metals. This represents an advantageous approach that avoids the use of sensitive and expensive organometallic compounds. For example, we have demonstrated the direct use of samarium metal in organic synthesis in recent publications. Parallel to our research, several other groups also have demonstrated new chemistry by samarium-induced reactions. This review is focused on the application of samarium-induced organic reactions. The advantages of using samarium metal in terms of reactivity, yield of the products, and selectivity in several organic transformations are discussed. Special attention is paid to the chemistry developed in our laboratory. A suggestion of reactive intermediates is also presented.