Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Abstract

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.

Development of Customized [18F]Fluoride Elution Techniques for the Enhancement of Copper-Mediated Late-Stage Radiofluorination

“…Yields of [ 18 F]FAP were comparable to those obtained using traditional S N Ar: 61 ± 8% using optimized manual conditions and 8–12% when the process was automated 21, 41 . We used N -bromosuccinimide (NBS) in the presence of methanesulfonic acid for the bromination, as it is a relatively mild method for the α-bromination of ketones that is amenable to automation 45, 46 . However, attempts to brominate the [ 18 F]FAP ( 2 ) produced in this fashion proceeded in ≤5% RCC (Fig.…”

Applications of Selenonium Cations as Lewis Acids in Organocatalytic Reactions

“…Although alkyl selenonium salts are potential alkylating agents and aBrønsted acid could be given as the by-product, no catalyst decomposition was observed in the current study,and control experiments were carried out to exclude the possibility of Brønsted catalysis. It is also worth mentioning that position-selective monobromination of these polycyclic arenes is not atrivial task and amixture of polyhalogeneated products are commonly observed when using conventional halogenation protocols.While there are several protocols that involve the use of metal catalysts or molecular bromine could effect the positional selective aromatic halogenation reactions, [21] the reaction system with 6 as the catalyst offers amild and metal-free alternative. [19] Va rious arenes were then examined and the results are shown in Table 2.…”

Multiple Halogenation of Aliphatic C−H Bonds within the Hofmann–Löffler Manifold

“…Given the observed higher stability in the cases of the brominated adamantyl derivatives and the general interest in brominated organic compounds as important synthons, polybromination was investigated further for additional alicyclic substrates (Scheme ). For indane‐derived substrates 5 a – c , the 2‐ethylenylamides induced selective 1,5‐HAT at the benzylic positions, demonstrating that dual halogenation is also possible involving methylene groups.…”

“…Given the observedh igher stabilityi nt he cases of the brominateda damantyl derivatives and the general interesti nb rominatedo rganic compounds as important synthons, [20] polybromination was investigated further for additional alicyclic substrates (Scheme 3). For indane-derived substrates 5a-c,t he 2-ethylenylamides induced selective 1,5-HATa tt he benzylic positions, demonstrating that dual halogenation is also possible involving methylene groups.C oncomitantc yclization took place to provide the annelated pyrrolidines 6a-c as single diastereoisomers.T he same occurred for the related tetrahydronaphthalene substrates, which displayed additional selective CÀHb romination from 1,5-and 1,6-HAT, affording products 6e,f,w hich are also formed in ac ompletely diastereoselective manner.I nc ase of ah igher excess of hydantoin 2b,d ibrominated ketone 6d was obtained as as ingle diastereomer,i n which the carbonyl group was formed from hydrolysis of the geminal dibromination product.…”