Recent Developments in Samarium Diiodide Promoted Organic Reactions

Abstract

In the early eighties, we introduced samarium diiodide for the transformation of various functional groups. Since then, this reducing agent has been extensively used for the reductive cleavage of single bonds, C-C bond formations, C-N bond formations, and β-elimination reactions. In this Personal Account, we highlight our initial results, as well as some of the contributions from various research groups. Because of space limitations, we arbitrarily select some useful results that have recently been described in literature.

Diastereoselective Hydroxyethylation of β‐Hydroxyketones: A Reformatsky Cyclization‐Lactone Reduction Cascade Mediated by SmI2−H2O

“…[1][2][3][4][5] The motif is most often constructed by diastereoselective ketone reduction. [6][7][8][9][10][11][12] Samarium diiodide (Kagan's reagent, SmI 2 ) is well-known for its ability to form carbonÀ carbon bonds, with high diastereoselectivity, [13][14][15] particularly when couplings are carried out in an intramolecular sense. Recently, our group has expanded the synthetic reach of the reagent by developing chemistry involving radicals generated from the carbonyl groups of carboxylic acid derivatives.…”

“…-NMR (101 MHz, CDCl 3 ): 25.9 (CH 2 Br); 30.7 (Me); 37.4 (CH 2 CH=CHAr); 46.6 (CH 2 C(O)), 71.6 (CH); 123.9 (CH=CHAr); 126.3 (ArCH); 127.7 (ArCH); 128.7 (ArCH); 134.1 (CH = CHAr); 137.0 (ArC); 166.6 (C(O)CH 2 Br), 205.1 (CO). HR-MS: 325.0427 (C15 H 18 O 3 Br + , [M + H] + ; calc. 325.0434).…”

Cross-Coupling Reactions Using Samarium(II) Iodide

“…Since its introduction to organic synthesis in 1977 by Kagan, , samarium­(II) iodide (SmI 2 , Kagan’s reagent) has gained the status of one of the most versatile single-electron transfer reagents available in the laboratory. − SmI 2 occupies a unique place among other reductants − in that it is an extremely powerful − yet chemoselective reagent, whose selectivity toward functional groups is fine-tuned by the use of appropriate ligands and additives. − Transformations mediated by SmI 2 are performed under user-friendly and operationally simple reaction conditions, resulting in one of the most straightforward ways to achieve single-electron reductions, a fact that has been successfully exploited in both academic and industrial settings . Of particular note is the ability of samarium diiodide to operate through either one- or two-electron reductive pathways, often proceeding with exquisite control of structure and stereochemistry, and providing reaction outcomes complementary to other reductants in the processes mediated by this reagent.…”

“…Samarium­(II) iodide has been the subject of previous reviews. These publications have addressed general aspects of application of the reagent, − the use of SmI 2 in the synthesis of natural products, − chemoselective reductions, functional group manipulations, − applications in asymmetric synthesis, mechanistic aspects, influence of the additives, − sequential reactions, and specific transformations, − among others. , …”

A computational study of samarium diiodide‐induced cyclizations of N‐oxoalkyl‐substituted methyl indole‐3‐carboxylates—A rationale of the diastereoselectivity

“…Samarium diiodide (SmI 2 ) is a selective one‐electron donating agent introduced by Kagan in 1977, hence known as “Kagan's reagent.” It was found to be a very useful reducing agent in a variety of synthetic transformations . One of these, the SmI 2 mediated reductive cyclization of N ‐oxoalkyl‐substituted methyl indole‐3‐carboxylates A (see Fig.…”