Spectroscopic and Computational Study of the Organocatalytic Umpolung of Bromocations: An Accelerated Stereoselective Dibromination Protocol**

Abstract

Herein, organocatalytically achieved polarity reversal of cationic bromine is presented. The proven bromocation source N‐bromosuccinimide (NBS) was converted to a superior bromoanion reagent by H/Br exchange with a secondary amine, substantiated with spectroscopic and computational evidence. The concept has further been used in a successfully accelerated organocatalyzed dibromination of olefins in a non‐hazardous, commercially viable process with a wide range of substrate scope. The reactivity of key entities observed through NMR kinetics and reaction acceleration using only 10 mol % of catalyst account for its major success. The nucleophilicity of the bromoanion was found to be superior in comparison to other nucleophiles such as MeOH and H2O also the protocol dominates over the competing allylic bromination reaction.