Selective reductive transformations using samarium diiodide-water

Samarium diiodide (SmI 2) is one of the most important reductive electron transfer reagents available in the laboratory. Key to the popularity of SmI 2 is the ability of additives and co-solvents to tune the properties of the reagent. Over the last decade water has emerged as a particularly valuable additive, opening up new chemical space and leading to the discovery of unprecedented selectivity and new reactions promoted by SmI 2. In this Feature Article we review recent progress in the application of SmI 2-H 2O systems, with an emphasis on mechanistic considerations and the development of new transformations.