The Introduction of Nitrile-Groups into Heterocycles and Concversion of Carboxylic Groups into their Corresponding Nitriles with Clorosulfonylisocyanate and Triethylamine

Article abstract of DOI:10.1016/S0040-4020(01)89685-X

Addition of chlorosulfonylisocyanate (CSI) to heterocycles such as thiophene (4) or indole (15) and unsaturated systems such as dihydropyran (7) gives N-chlorosulfonylamides RCONHSO2Cl, which can be converted by equivalent amounts of triethylamine to their corresponding nitriles.Since carboxylic acids react with CSI to N-chlorosulfonylamides, subsequent treatment with triethylamine affords the corresponding nitriles, but no isocyanates as claimed by other authors.The mechanisms of the conversion of the intermediate N-chlorosulfonylamides into the corresponding nitriles are discussed.