Mechanistic Vistas of Trivalent Nitrogen Compound Reduction by Samarium Diiodide

In trivalent nitrogen compounds, the nitrogen lone pair is highly amenable to bind to samarium iodide prior to electron transfer. As SmI₂ is more azaphilic than oxophilic, its affinity to the nitrogen lone pair is more pronounced in aza substrates than in the analogous carbonyl compounds. The impact of this binding is very large in terms of reaction rate and at the same time gives rise to unique mechanistic phenomena, which include unusual kinetic rate orders, catalysis by quantum dots, and remote functionalization. Even reduction of nitriles was found to be affected by this coordination to SmI₂. This review focuses on the reduction mechanisms of three groups of compounds: imines, azobenzene, and nitriles.