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Updated: Jul 27, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Spectroscopic and Computational Study of the Organocatalytic Umpolung of Bromocations: An Accelerated Stereoselective
Jeetendra Panda1, Jigyansa Sahoo1, Juhi Dutta2,3
1Department of Chemistry, National Institute of Technology Rourkela, Rourkela, Odisha, 769008, India.
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 H2 O also the protocol dominates over the competing allylic bromination reaction.
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