Improved Synthetic Utility of a Sluggish Electrophile: Reaction of Chlorosulfonyl Isocyanate with Unreactive and Reactive Alkenes

Abstract Chlorosulfonyl isocyanate (CSI) is a sluggish electrophile in reactions with electron-deficient alkenes or with many monofluoroalkenes. The efficiency of these reactions is improved at temperatures between –15 and 25 °C because, at these temperatures, CSI and the alkene are in equilibrium with an intermediate. A unimolecular reaction of the intermediate at a temperature between –15 and 25 °C is more efficient than the bimolecular reaction of the dissociated reagents above room temperature. This finding provides a method for improving the reactions of CSI with unreactive alkenes.