Poly(vinylpyrrolidone)-bromine Complex; a Mild and Efficient Reagent for Selective Bromination of Alkenes and Oxidation of Alcohols

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

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.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

Bromination of olefins with HBr and DMSO

A simple and inexpensive methodology is reported for the conversion of alkenes to 1,2-dibromo alkanes via oxidative bromination using HBr paired with dimethyl sulfoxide, which serves as the oxidant as well as cosolvent. The substrate scope includes 21 olefins brominated in good to excellent yields. Three of six styrene derivatives yielded bromohydrins under the reaction conditions.