Fluorosulfonyl azide is an inorganic compound with the chemical formula . This is a derivative of sulfuric acid containing a fluorine atom and an azide group. The compound is used as a reagent for transferring diazo groups.
Fluorosulfonyl azide can be prepared by reacting disulfuryl fluoride (F<sub>2</sub>S<sub>2</sub>O<sub>5</sub>) with sodium azide in nitromethane or sulfolane.
Fluorosulfonyl azide is a diazo group transfer reagent. It is suitable, for example, for preparing azides from primary amines in a click reaction. Diazo reagents can be prepared starting from using fluorosulfonyl azide. If diazabicycloundecene is added as a base, the is obtained. With magnesium oxide, the Seyferth-Gilbert reagent is obtained.
These reagents are used to convert aldehydes into alkynes. With the two precursors, such a reaction is also possible as a one-pot synthesis. In this case, an aldehyde is added directly and potassium carbonate is used as the base.