The Development and Application of Sulfur Dioxide Surrogates in Synthetic Organic Chemistry

Sulfur dioxide has a rich and varied chemistry that can be traced back to the early 1900s. Despite the potential utility of sulfur dioxide based reactions, delivering products such as sulfones, sulfonamides and sulfinic acids, the number of examples of these reactions being exploited in synthesis is arguably lower than would be expected. One significant contributing factor to this is undoubtedly the toxic and gaseous nature of SO2. One strategy to overcome this limitation is to employ an equivalent, or surrogate, so that the gaseous reagent is no longer needed. This strategy has proven to be a success, with a number of methods being described. The reactions reported include variants of traditional reactions in which the gaseous reagent has been replaced with a surrogate, and also new transformations for which no gaseous reaction is known. This Focus Review discusses the origin of sulfur dioxide surrogates and then considers their application to synthetic organic chemistry.