o-Benzenedisulfonimide: An Organic Reagent and Organocatalyst of Renewed Interest

Synthesized nearly one century ago as a saccharine-like sweetener compound, the o-benzenedisulfonimide has received a discontinuous attention in the past. In the last century, various synthetic procedures have been reported, in confirmation of the interest in this intriguing compound. In recent years, it has been used as a leaving group in reactions of nucleophilic substitution of amines with alcohols or phenols to give the corresponding ethers. Its N-fluoroderivative is a stable and efficient fluorinating agent, which has found applications in several asymmetric syntheses. In previous studies, its conjugated base has been extensively used as stabilizing counter-ion of arenediazonium salts; safely isolated and stored in a dry state, ready to use, they have been applied successfully in many dediazoniation reactions, with interesting mechanistic insights. More recently, due to its high acidity, the o-benzenedisulfonimide has been used in catalytic amounts in some common acid-catalyzed organic reactions. Valuable aspects of this catalyst are its easy recovery from the reaction mixture and its reuse in other reactions, with clear economic and ecological advantages. Finally, the disulfonimide functional group has been proposed as a powerful chiral motif for strong Brønsted acids in asymmetric organocatalysis.