25245-34-5Relevant articles and documents
Using NBS as a mild bromination reagent for polyalkoxyaromatic systems
Bloomer, James L.,Zheng, Wei
, p. 2087 - 2095 (1998)
N-Bromosuccinimide in Methylene Chloride is A Mild Mono- or Dibromination Reagent for Polyalkoxyaromatic Compounds Including Those Which are too Labile to be Brominated with Molecular Bromine.
Direct bromodeboronation of arylboronic acids with CuBr2 in water
Tang, Yan-Ling,Xia, Xian-Song,Gao, Jin-Chun,Li, Min-Xin,Mao, Ze-Wei
supporting information, (2021/01/05)
An efficient and practical method has been developed for the preparation of aryl bromides via the direct bromodeboronation of arylboronic acids with CuBr2 in water. This strategy provides several advantages, such as being ligand-free, base-free, high yielding, and functional group tolerant.
Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
Arrieta, Ana,Cossío, Fernando P.,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
, p. 2142 - 2150 (2020/03/11)
A mild, metal-free bromination method of arenes has been developed using the combination of bis(trifluoroacetoxy)iodobencene and trimethylsilyl bromide. In situ-formed dibromo(phenyl)-λ3-iodane (PhIBr2) is proposed as the reactive intermediate. This methodology using PIFA/TMSBr has been applied with success to a great number of substrates (25 examples). The treatment of mono-substituted activated arenes led to para-brominated products (2u-z) in excellent 83-96% yields. Density functional theory calculations indicate a stepwise mechanism involving a double bromine addition followed by a type II dyotropic reaction with concomitant re-aromatization of the six-membered ring.
A silica-gel accelerated [4 + 2] cycloaddition-based biomimetic approach towards the first total synthesis of magterpenoid C
Kumar, Dileep,Kumar, Virendra,Salam, Abdus,Khan, Tabrez
, (2019/09/17)
The first total synthesis of magterpenoid C has been realized via a silica gel accelerated biomimetic Diels-Alder reaction between β-myrcene and randaiol derived quinone. However, application of similar strategy towards magterpenoid B via a protective Diels-Alder reaction failed to deliver the natural product.
Regioselective Oxybromination of Benzene and Its Derivatives by Bromide Anion with a Mononuclear Nonheme Mn(IV)-Oxo Complex
Sharma, Namita,Lee, Yong-Min,Li, Xiao-Xi,Nam, Wonwoo,Fukuzumi, Shunichi
supporting information, p. 14299 - 14303 (2019/11/03)
Oxybromination of aromatic compounds by high-valent metal-oxo intermediates has yet to be explored despite extensive studies on the oxybromination of aliphatic C-H bonds of hydrocarbons. Herein, we report the regioselective oxybromination of methoxy-substituted benzenes by a nonheme MnIV-oxo complex binding scandium ions, [(Bn-TPEN)MnIV(O)]2+-(Sc(OTf)3)2 (1), in the presence of tetrabutylammonium bromide. The regioselective oxybromination occurs at the carbon atom with the highest positive charge via electron transfer (ET) from the methoxy-substituted benzenes to 1. ET driving force dependence of the rate constants of ET from methoxy-substituted benzenes to 1 is well fitted in light of the Marcus theory of ET. Under photoirradiation, the oxybromination of benzene by 1 can be achieved via ET from benzene to the photoexcited state of 1, although no reaction occurs between benzene and the ground state of 1 in the dark. To the best of our knowledge, this is the first example of reporting the stoichiometric regioselective oxybromination of the benzene ring by a synthetic high-valent Mn(IV)-oxo complex and the catalytic regioselective oxybromination reaction with a Mn(II) complex and a terminal oxidant.
Preparation of a novel bromine complex and its application in organic synthesis
Nishio, Yuya,Yubata, Kotaro,Wakai, Yutaro,Notsu, Kotaro,Yamamoto, Katsumi,Fujiwara, Hideki,Matsubara, Hiroshi
, p. 1398 - 1405 (2019/02/07)
Although molecular bromine (Br2) is a useful brominating reagent, it is not easy to handle. Herein, we describe the preparation of a novel air-stable bromine complex prepared from 1,3-dimethyl-2-imidazolidinone (DMI) and Br2, which was identified to be (DMI)2HBr3 by spectral and X-ray techniques. This complex was then used to brominate olefins, carbonyl compounds, and aromatics, as well as in the Hofmann rearrangement. Yields of reaction products using this complex were almost the same or superior to those using other bromine alternatives.
Atom-economical brominations with tribromide complexes in the presence of oxidants
Yubata, Kotaro,Matsubara, Hiroshi
supporting information, p. 1001 - 1004 (2019/03/13)
Bromination is an important transformation in organic synthesis, and novel efficient bromination techniques are still required. Herein, we demonstrate atom-economical brominations using (DMI)2HBr3, a novel tribromide complex, with oxidants such as DMSO and Oxone. Using this system, olefinic and aromatic brominations, as well as selective α-monobrominations of ketones proceeded well to afford the desired bromides in good yields. Importantly, in these reactions all of the bromine atoms in this complex are used to brominate.
Preparation method of 2,5-dihydroxybenzaldehyde
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Paragraph 0013-0015; 0020-0022, (2019/10/29)
The invention provides a method for synthesizing 2,5-dihydroxybenzaldehyde. The method comprises the following steps: with p-dimethoxybenzene as a raw material, carrying out bromination reaction, Grignard reaction and demethylation reaction to obtain the 2,5-dihydroxybenzaldehyde. The preparation conditions are mild, the process is simple, and the industrial application value is high.
Bromine formation in solid NaBr/KNO3 mixture and assay of this reaction via bromination of activated aromatics
Rahu, Ida,Keki?ev, Ott,J?rv, Jaak,Burk, Peeter
, p. 2893 - 2898 (2018/08/23)
Bromine formation in the mixture of solid NaBr and KNO3 was observed and the process was studied in different acidified organic solvent–water mixtures by monitoring the bromination of acetanilide and other compounds, containing activated aromatic substituents. This assay is based on fast bromination reaction of these aromatic compounds, as differently from the assay of Br2, the brominated aromatics can be easily determined by conventional gas chromatography–mass spectrometry (GC–MS) methods. It was found that bromine was generated autocatalytically on the surface of salt crystals and the reaction was characterized by a lag period, the duration of which depended on reaction conditions, and importantly on the type of the organic solvent in the reaction mixture. As the bromine formation could be easily controlled by reaction conditions, it was suggested that the studied reaction might have practical applications as an environmentally friendly and economically feasible bromination method. It was also shown that the bromination of aromatics followed the mechanism of classical electrophilic aromatic substitution reaction.
NOVEL CYCLIC UREA DERIVATIVE-HYDROTRIBROMIDE
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Paragraph 0039; 0040; 0041, (2018/11/22)
PROBLEM TO BE SOLVED: To provide a novel bromination agent easy to handle. SOLUTION: There are provided a compound represented by a general formula (1) where n is 1 or 2, R1 and R2 may be same or different and represent an alkyl group having 1 to 4 carbon atoms, preferably a methyl group, and a bromination agent using the same. EFFECT: A cyclic urea derivative-hydrotribromide, which can be used as the bromination agent, can be provided, and the compound can be applied to various bromination reactions because it is stable solid and is easy to handle. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
