Mechanistic Vistas of Trivalent Nitrogen Compound Reduction by Samarium Diiodide

Abstract

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.

Samarium(II)‐Promoted Cyclizations of Nonactivated Indolyl Sulfinyl Imines to Polycyclic Tertiary Carbinamines

“…In the case of the cyclizations of ketones A the samarium ketyl involved bears probably four very bulky HMPA ligands whereas the corresponding samarium azaketyl J' derived from imine E is probably surrounded by water molecules. Furthermore, the interaction of the oxygen with the oxophilic samarium(II) center of the ketyl may be different than that in the corresponding azaketyls [33,34] . These differences may lead to less steric compression at the nitrogen making R 2 and the NHSm(III)L n moiety similar in size in most cases.…”

Samarium-Mediated Asymmetric Synthesis

“…The enhanced reduction potential of SmI2 with HMPA allows the formation of various reactive intermediates leading to the access of complex architecture [26,27]. In this context, the enormous applications of SmI2 in the key reaction step during the total synthesis of natural products is remarkable [28][29][30][31][32].…”