Neutral Organic Electron Donor Cleaves Sulfonyls

A neutral organic compound that gives away its electrons with unusual enthusiasm may be an important new tool for a major area of organic and medicinal chemistry: the reductive cleavage of sulfones and sulfonamides (J. Am. Chem. Soc. 2007, 129, 13368). These ubiquitous reactions typically have relied on brutish metal-based reducing agents, such as lithium, sodium, or nickel-containing compounds. John A. Murphy and colleagues at the University of Strathclyde, in Glasgow, Scotland, discovered that the bisimidazolylidene shown readily breaks arenesulfonyl groups off of monosulfones, indolesulfonamides, and anilinesulfonamides. The reagent transfers two electrons to the arenesulfonyl groups, in the latter cases breaking the very strong N???S bond of sulfonamides in the process. Although the reagent is not new, its strong reductive powers hadn't previously been applied to organic substrates. Murphy's group has been studying the chemistry of such "super electron donors," which led the team to develop an easy synthetic route to this bisimidazolylidene.