Applications of trisulfide radical anion S3˙− in organic synthesis

Abstract

The trisulfide radical anion S₃˙⁻ is well-known as the blue chromophore in ultramarines and it has a versatile role in materials chemistry, especially in the redox chemistry of alkali metal–sulfur batteries, electrochemistry, analytical chemistry and geochemistry. However, the applications of this unique sulfur reagent in organic chemistry have only been exploited in the last ten years. This versatile source of sulfur can be easily formed by reaction of elemental sulfur (S₈) with nucleophilic bases or by oxidation of sulfide (S²⁻) in readily available alkali–metal salts. Recent findings have revealed that S₃˙⁻ has a multi-faceted role in a variety of organic reactions for the synthesis of organosulfur compounds with applications ranging from pharmaceuticals to organic semiconductors. In addition, S₃˙⁻ may serve as a catalyst in certain organic transformations such as C–C bond formation cross-coupling reactions. In this review, the synthetic and mechanistic aspects of the role of the trisulfur radical anion S₃˙⁻ in organic chemistry are discussed.