22002-45-5Relevant academic research and scientific papers
MECHANISM OF ISOMERISATION OF ortho OR para BROMO PHENOLS IN SUPERACIDS
Jacquesy, Jean-Claude,Jouannetaud,Marie-Paule
, p. 1673 - 1676 (1982)
In superacids ortho or para bromo phenols are isomerised into the meta bromo isomers.In SbF5-HF, the process is intramolecular and proceeds by a 1,2-Br shift.In CF3SO3H, the mechanism involves loss of bromine, followed by meta bromination.
1,5-diketones from 3,4-dihydropyranones: An application in the synthesis of (±)-α-herbertenol
Harrowven, David C.,Hannam, Joanne C.
, p. 9333 - 9340 (1999)
An approach to 1,5-diketones involving the addition of organolithium reagents to 3,4-dihydropyranones is described. Good yields are obtained when reactions are quenched with trimethylsilyl chloride prior to hydrolytic work up and the organolithium reagent contains a Lewis basic group adjacent to the carbon to lithium bond. The method has been applied in a short synthesis of the fungicidal sesquiterpene (±)-α-herbertenol.
Bridged nitrogen-containing heterocyclic metallocene compound as well as preparation method and application thereof
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Paragraph 0100; 0121, (2021/10/16)
The invention provides a bridged nitrogen-containing heterocyclic metallocene compound, which has the structure shown in the formula (I). In-flight R1 A substituted or unsubstituted C1 - C30 alkyl group, a substituted or unsubstituted C3 - C30 cycloalkyl group, a substituted or unsubstituted C6 - C30 aromatic group, a substituted or unsubstituted C6 - C30 aromatic heterocyclic group. R2 AND R3 A C1 - C10 alkyl group or a phenyl group is each independently selected. R4 A substituted or unsubstituted C1 - C10 alkyl, substituted or unsubstituted C6 - C20 aromatic group. X Is a halogen, a substituted or unsubstituted alkyl group. M Is 4th-valent transition metal titanium. Zircon or hafnium. Compared with the prior art, the metallocene compound provided by the invention is convenient to modify, high in catalytic activity and good in temperature resistance, can maintain high catalytic activity under high-temperature conditions, can catalyze copolymerization of ethylene and α - olefin, and can obtain a polymer product with high molecular weight and high comonomer insertion rate.
Visible light-induced mono-bromination of arenes with BrCCl3
Fan, Jiali,Wei, Qiancheng,Zhu, Ershu,Gao, Jing,Cheng, Xiamin,Lu, Yongna,Loh, Teck-Peng
supporting information, p. 5977 - 5980 (2021/06/18)
A highly efficient and regioselective bromination of electron-rich arenes and heteroarenes using commercially available BrCCl3as a “Br” source has been developed. The reaction was performed in air under mild conditions with photocatalyst Ru(bpy)3Cl2·6H2O, avoiding the usage of strong acids and strong oxidants. Mono-brominated products were obtained with medium to excellent yields (up to 94%). This strategy has shown good compatibility and highpara-selectivity, which will facilitate the complicated synthesis.
Eco-Friendly Methodology for the Formation of Aromatic Carbon–Heteroatom Bonds by Using Green Ionic Liquids
Richards, Kenza,Petit, Eddy,Legrand, Yves-Marie,Grison, Claude
supporting information, p. 809 - 814 (2020/11/30)
A new sustainable method is reported for the formation of aromatic carbon–heteroatom bonds under solvent-free and mild conditions (no co-oxidant, no strong acid and no toxic reagents) by using a new type of green ionic liquid. The bromination of methoxy arenes was chosen as a model reaction. The reaction methodology is based on only using natural sodium bromine, which is transformed into an electrophilic brominating reagent within an ionic liquid, easily prepared from the melted salt FeCl3 hexahydrate. Bromination reactions with this in-situ-generated reagent gave good yields and excellent regioselectivity under simple and environmentally friendly conditions. To understand the unusual bromine polarity reversal of sodium bromine without any strong oxidant, the molecular structure of the reaction medium was characterised by Raman and direct infusion electrospray ionisation mass spectroscopy (ESI-MS). An extensive computational investigation using density functional theory methods was performed to describe a mechanism that suggests indirect oxidation of Br? through new iron adducts. The versatility of the methodology was successively applied to nitration and thiocyanation of methoxy arenes using KNO3 and KSCN in melted hexahydrated FeCl3.
New procedure for the highly regioselective aerobic bromination of aromatic compounds using copper-based nanocatalyst
Albadi, Jalal,Jalali, Mehdi
, p. 234 - 239 (2020/02/29)
A new procedure for the highly regioselective aerobic bromination of aromatic compounds in the presence of copper-based nanoparticles (CuO/ZnO nanocatalyst) under reflux condition is described. Mechanistic parameters are discussed and the plausible mechanism is proposed. Recyclability of the CuO/ZnO nanocatalyst has also been explored upon aerobic bromination of aromatic compounds.
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.
Environmentally benign indole-catalyzed position-selective halogenation of thioarenes and other aromatics
Shi, Yao,Ke, Zhihai,Yeung, Ying-Yeung
supporting information, p. 4448 - 4452 (2018/10/17)
Halogenated aromatic compounds are the cores of many pharmaceutical, agricultural and chemical products but they are commonly prepared using electrophilic halogenation reactions in non-green chlorinated solvents under harsh conditions. A separate problem happens in the aromatic halogenation of thioarenes because they readily undergo oxidative side-reactions. Herein we report an environmentally benign electrophilic bromination of aromatics using an indole-catalytic protocol, which is suitable for a wide range of substrates including thioarenes.
Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
Ni, Shengjun,El Remaily, Mahmoud Abd El Aleem Ali Ali,Franzén, Johan
supporting information, p. 4197 - 4204 (2018/09/25)
The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C?H functionalization and arene sp2 C?H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 C?Br and sp2 C?Br functionality. (Figure presented.).
Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
Zhao, Mengdi,Li, Meiqi,Lu, Wenjun
supporting information, p. 4933 - 4939 (2018/12/14)
Benzylic sp 3 C-H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO 2 Et, CO 2 H, CN or NO 2, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.
