Saccharin Reaction with Cyanide

A novel reaction between saccharin (1,2-benzisothiazole-3(2H)-one-1,1-dioxide, o-sulfobenzimide, or obenzoic sulfimide) and cyanide to afford an unexpected compound, 2-(cyanosulfonyl)benzamide, has been described. Cyanide ion proved to attack the sulfonyl group of o-sulfobenzimide over 170 °C to open the ring and to add to form a new C-S bond. This is an unexpected reaction, as the leading theory of chemical reaction predicts cyanide to be too weak to react with sulfonyl groups. The spectroscopic data and the elemental analyses confirm the structure of the resulted compound and support the mechanism of reaction. The reaction pathway is important from the theoretical point of view, however it might serve both preparative and analytical purposes.