- 1,2-Silyl migration in 1-halonaphthalenes catalyzed by I2
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1-Halo-8-hydrosilylnaphthalenes undergo 1,2-silyl migration to form 1-halo-7-silylnaphthalenes. The influence of the substituents on the silicon atom, the solvent effect, and the D-labeling experiments are investigated. The migration process may include four steps: (a) generation of acid (HI) by the reaction of the hydrosilane with I2, (b) protonation of the naphthalene ring, (c) silyl group migration in the protonated intermediate, and (d) deprotonation of the naphthalene ring.
- Shimizu, Tomomi,Morisako, Shogo,Yamamoto, Yohsuke,Kawachi, Atsushi
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Read Online
- Hydrogen-Bond-Donor Solvents Enable Catalyst-Free (Radio)-Halogenation and Deuteration of Organoborons
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A hydrogen bond donor solvent assisted (radio)halogenation and deuteration of organoborons has been developed. The reactions exhibited high functional group tolerance and needed only an ambient atmosphere. Most importantly, compared to literature methods, our conditions are more consistent with the principals of green chemistry (e.g., metal-free, strong oxidant-free, more straightforward conditions).
- Yang, Yi,Gao, Xinyan,Zeng, Xiaojun,Han, Junbin,Xu, Bo
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supporting information
p. 1297 - 1300
(2020/12/23)
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- A Visible Light and Iron-mediated Carbocationic Route to Polysubstituted 1-Halonaphthalenes by Benzannulation using Allylbenzenes and Polyhalomethanes
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A wide array of polysubstituted 1-bromo and chloronaphthalenes are obtained from coupling of allylbenzenes and polyhalomethanes. The reaction is mediated by iron metal under visible light irradiation and proceeds via a Kharasch addition intermediate followed by intramolecular FeIII mediated Friedel-Crafts alkylation, with the formation of two Csp2?Csp2 bonds in the process. This method gives easy access to 1-halonaphthalenes with substituent(s) at C-5 to C-8 that are otherwise hard to synthesize. (Figure presented.).
- Roslan, Irwan Iskandar,Zhang, Hongwei,Ng, Kian-Hong,Jaenicke, Stephan,Chuah, Gaik-Khuan
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p. 1007 - 1013
(2020/12/30)
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- Direct bromodeboronation of arylboronic acids with CuBr2 in water
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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.
- Tang, Yan-Ling,Xia, Xian-Song,Gao, Jin-Chun,Li, Min-Xin,Mao, Ze-Wei
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supporting information
(2021/01/05)
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- Triptycenyl Sulfide: A Practical and Active Catalyst for Electrophilic Aromatic Halogenation Using N-Halosuccinimides
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A Lewis base catalyst Trip-SMe (Trip = triptycenyl) for electrophilic aromatic halogenation using N-halosuccinimides (NXS) is introduced. In the presence of an appropriate activator (as a noncoordinating-anion source), a series of unactivated aromatic compounds were halogenated at ambient temperature using NXS. This catalytic system was applicable to transformations that are currently unachievable except for the use of Br2 or Cl2: e.g., multihalogenation of naphthalene, regioselective bromination of BINOL, etc. Controlled experiments revealed that the triptycenyl substituent exerts a crucial role for the catalytic activity, and kinetic experiments implied the occurrence of a sulfonium salt [Trip-S(Me)Br][SbF6] as an active species. Compared to simple dialkyl sulfides, Trip-SMe exhibited a significant charge-separated ion pair character within the halonium complex whose structural information was obtained by the single-crystal X-ray analysis. A preliminary computational study disclosed that the πsystem of the triptycenyl functionality is a key motif to consolidate the enhancement of electrophilicity.
- Nishii, Yuji,Ikeda, Mitsuhiro,Hayashi, Yoshihiro,Kawauchi, Susumu,Miura, Masahiro
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supporting information
p. 1621 - 1629
(2020/02/04)
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- Molecular tweezers based on trivalent phosphine, preparation method of molecular tweezers, metal-molecular tweezers catalyst, and preparation method and application of metal-molecular tweezers catalyst
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The invention relates to the technical field of inorganic-metal organic crossing and relates to the technical field of molecular tweezers, in particular to molecular tweezers based on trivalent phosphine, a preparation method of the molecular tweezers, a metal-molecular tweezer catalyst, a preparation method of the metal-molecular tweezer catalyst and an application of the metal-molecular tweezercatalyst, the molecular tweezer based on trivalent phosphine is named as P-MV-PCN-521-R, and R is any one of benzoic acid, p-nitrobenzoic acid, formic acid, p-methylbenzoic acid and dichloroacetic acid. The molecular tweezers based on the trivalent phosphine have distance adjustability. The trivalent phosphine-based metal-molecular tweezer catalyst provided by the invention has a high crystallinesurface area and a high specific surface area. The trivalent phosphine-based metal-molecular tweezer catalyst has good chemical stability and thermal stability, and is a primary condition for applyingthe trivalent phosphine-based metal-molecular tweezer catalyst to the actual field. The trivalent phosphine-based metal-molecular tweezer catalyst with adjustable distance provided by the invention has good selectivity for bromination of aromatic compounds.
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Paragraph 0038; 0059-0060
(2020/12/14)
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- Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
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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.
- Arrieta, Ana,Cossío, Fernando P.,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
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p. 2142 - 2150
(2020/03/11)
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- Electrocatalytic Deuteration of Halides with D2O as the Deuterium Source over a Copper Nanowire Arrays Cathode
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Precise deuterium incorporation with controllable deuterated sites is extremely desirable. Here, a facile and efficient electrocatalytic deuterodehalogenation of halides using D2O as the deuteration reagent and copper nanowire arrays (Cu NWAs) electrochemically formed in situ as the cathode was demonstrated. A cross-coupling of carbon and deuterium free radicals might be involved for this ipso-selective deuteration. This method exhibited excellent chemoselectivity and high compatibility with the easily reducible functional groups (C=C, C≡C, C=O, C=N, C≡N). The C?H to C?D transformations were achieved with high yields and deuterium ratios through a one-pot halogenation–deuterodehalogenation process. Efficient deuteration of less-active bromide substrates, specific deuterium incorporation into top-selling pharmaceuticals, and oxidant-free paired anodic synthesis of high-value chemicals with low energy input highlighted the potential practicality.
- Chong, Xiaodan,Han, Shuyan,Li, Mengyang,Liu, Cuibo,Zhang, Bin
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supporting information
p. 18527 - 18531
(2020/08/21)
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- Molecular Vises for Precisely Positioning Ligands near Catalytic Metal Centers in Metal-Organic Frameworks
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We report the construction of a molecular vise by pairing a tritopic phenylphosphorus(III) linker and a monotopic linker in opposite positions within a metal-organic framework. The angle between these linkers at metal sites is fixed upon changing the functionality in the monotopic linker, while the distance between them is precisely tuned. This distance within the molecular vise is accurately measured by 1H-31P solid-state nuclear magnetic resonance spectroscopy. This unveils the impact of the distance on catalytic performance without interference from electrostatic effects or changes in the angle of the ligand, which is unprecedented in classic organometallic complexes.
- Yan, Wei,Li, Shenhui,Yang, Tao,Xia, Yucong,Zhang, Xinrui,Wang, Chao,Yan, Zier,Deng, Feng,Zhou, Qianghui,Deng, Hexiang
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supporting information
p. 16182 - 16187
(2020/10/26)
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- Orthogonal Stability and Reactivity of Aryl Germanes Enables Rapid and Selective (Multi)Halogenations
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While halogenation is of key importance in synthesis and radioimaging, the currently available repertoire is largely designed to introduce a single halogen per molecule. This report makes the selective introduction of several different halogens accessible. Showcased here is the privileged stability of nontoxic aryl germanes under harsh fluorination conditions (that allow selective fluorination in their presence), while displaying superior reactivity and functional-group tolerance in electrophilic iodinations and brominations, outcompeting silanes or boronic esters under rapid and additive-free conditions. Mechanistic experiments and computational studies suggest a concerted electrophilic aromatic substitution as the underlying mechanism.
- Deckers, Kristina,Fricke, Christoph,Schoenebeck, Franziska
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supporting information
p. 18717 - 18722
(2020/08/25)
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- Preparation method of 1-bromonaphthalene
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Belonging to the technical field of chemical synthesis, the invention specifically relates to a preparation method of 1-bromonaphthalene. The method includes: (1) dissolving naphthalene fully in dichloroethane, and adding hydrobromic acid under stirring to form a mixed solution; (2) adding sodium hypochlorite into the mixed solution dropwise at 25-30DEG C, and conducting heat preservation stirring; (3) carrying out standing layering, taking the oil phase layer, and performing washing; and (4) conducting drying, and performing reduced pressure fractionation, thus obtaining 1-bromonaphthalene. The synthesis process adopted by the invention has the advantages of simple reaction device, few by-product, high yield, high utilization rate of bromine compared with other processes, low pollution ofthree wastes, low production energy consumption, high safety of the reaction process, and conforms to the green chemistry concept.
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Paragraph 0022; 0023; 0025; 0028; 0030-0033; 0037
(2019/05/08)
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- Regioselective arene homologation through rhenium-catalyzed deoxygenative aromatization of 7-oxabicyclo[2.2.1]hepta-2,5-dienes
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Combined use of oxorhenium catalysts with triphenyl phosphite as an oxygen acceptor allowed efficient deoxygenative aromatization of oxabicyclic dienes. The reaction proceeded under neutral conditions and was compatible with various functional groups. Combining this deoxygenation with regioselective bromination and trapping of the generated aryne with furan resulted in benzannulative π-extension at the periphery of the PAHs. This enabled direct use of unfunctionalized PAHs for extension of π-conjugation. Iteration of the transformations increased the number of fused-benzene rings one at a time, which has the potential to alter the properties of PAHs by fine-tuning the degree of π-conjugation, shape, and edge topology.
- Murai, Masahito,Ogita, Takuya,Takai, Kazuhiko
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supporting information
p. 2332 - 2335
(2019/02/27)
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- Nickel-catalyzed cross-coupling reaction of carbamates with silylmagnesium reagents
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The C–O bonds are kinetically inert in cross-coupling reactions compared to those of carbon–halogen bonds. Thus, developing methodologies for the activation of C–O bonds in cross-coupling reactions remains a major challenge. We disclose an unprecedented nickel mediated cross-coupling of carbamates with silylmagnesium reagents that does not require the expensive silylboranes. Silylmagnesium reagents were prepared from either silyllithium or silyl iodides. This methodology is distinguished by the synthesis of trimethylsilyl coupled product and its synthetic applications. Kinetic studies and radical clock experiments revealed the rate-limiting C–O bond cleavage, half order with respect to the catalyst and a non-radical transition state.
- Murugesan, Vetrivelan,Balakrishnan, Venkadesh,Rasappan, Ramesh
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p. 293 - 298
(2019/08/12)
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- Regioselective Halogenation of Arenes and Heterocycles in Hexafluoroisopropanol
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Regioselective halogenation of arenes and heterocycles with N-halosuccinimides in fluorinated alcohols is disclosed. Under mild condition reactions, a wide diversity of halogenated arenes are obtained in good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of one-pot sequential halogenation and halogenation-Suzuki cross-coupling reactions.
- Tang, Ren-Jin,Milcent, Thierry,Crousse, Benoit
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p. 930 - 938
(2018/01/28)
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- Transition-metal-free decarboxylative bromination of aromatic carboxylic acids
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Methods for the conversion of aliphatic acids to alkyl halides have progressed significantly over the past century, however, the analogous decarboxylative bromination of aromatic acids has remained a longstanding challenge. The development of efficient methods for the synthesis of aryl bromides is of great importance as they are versatile reagents in synthesis and are present in many functional molecules. Herein we report a transition metal-free decarboxylative bromination of aromatic acids. The reaction is applicable to many electron-rich aromatic and heteroaromatic acids which have previously proved poor substrates for Hunsdiecker-type reactions. In addition, our preliminary mechanistic study suggests that radical intermediates are not involved in this reaction, which is in contrast to classical Hunsdiecker-type reactivity. Overall, the process demonstrates a useful method for producing valuable reagents from inexpensive and abundant starting materials.
- Quibell, Jacob M.,Perry, Gregory J. P.,Cannas, Diego M.,Larrosa, Igor
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p. 3860 - 3865
(2018/04/26)
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- Regioselective monobromination of aromatics via a halogen bond acceptor-donor interaction of catalytic thioamide and N-bromosuccinimide
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Regioselective monobromination of various aromatics was achieved at room temperature using N-bromosuccinimide and 5 mol% of thioamides in acetonitrile. With thiourea as catalyst, activated aromatics, such as anisole, acetanilide, benzamide and phenol analogues containing electron donating or withdrawing groups, were brominated with high regioselectivity. Room temperature brominations of weakly activated aromatics and deactivated 9-fluorenone were accomplished by 5 mol% thioacetamide, higher substrates concentrations and longer reaction times. A backbonding of the bromine lone pairs with the π*of C[dbnd]S group and a halogen bond between the halogen bond donor bromine and the halogen bond acceptor sulfur of the thioamide are thought to be the principal interactions and cause of N-bromosuccinimide activation.
- Bovonsombat, Pakorn,Teecomegaet, Pattaradra,Kulvaranon, Panisanun,Pandey, Aditi,Chobtumskul, Kittithorn,Tungsirisurp, Sireethorn,Sophanpanichkul, Punyanuch,Losuwanakul, Satreerat,Soimaneewan, Dechathon,Kanjanwongpaisan, Patcharida,Siricharoensang, Pornpawit,Choosakoonkriang, Sirirat
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p. 6564 - 6572
(2017/10/17)
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- Method for synthesizing bromo-polycyclic aromatic hydrocarbon compound
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The invention discloses a method for synthesizing bromo-polycyclic aromatic hydrocarbon compounds. The method is characterized by comprising the following steps: utilizing a polycyclic aromatic hydrocarbon compound as a substrate, adding base metal bromide into a mixed solution of water and an organic solvent, then slowly adding ZnAl-BrO3--LDHs, reacting for 4 to 8h under 20 to 35 DEG C, TCL tracing a reaction process, washing a reaction mixture by a sodium sulfite solution after reaction is finished, extracting methylene dichloride, combining organic phases, reducing pressure and concentrating to obtain a coarse product, finally utilizing petroleum ether to ethyl acetate equal to (10 to 15) to 1 as an eluent and performing column chromatography isolation to obtain a mono bromo-polycyclic aromatic hydrocarbon compound or a dual brominated polycyclic aromatic hydrocarbon compound respectively. A brominating reagent utilized in the method disclosed by the invention is solid matter and is low in cost, easy to obtain and environmentally friendly. The method has the advantages of moderate reaction condition, convenience in aftertreatment, simpleness in reaction operation, high atom utilization rate, high selectivity, high target product yield and small side reaction.
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Paragraph 0032-0034; 0038; 0042; 0066; 0070
(2017/12/29)
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- A highly efficient heterogeneous copper-catalyzed chlorodeboronation of arylboronic acids leading to chlorinated arenes
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A highly efficient heterogeneous copper-catalyzed chlorodeboronation of arylboronic acids with inexpensive N-chlorosuccinimide (NCS) was achieved in MeCN in the presence of 10 mol% of l-proline-functionalized MCM-41-immobilized copper(i) complex [MCM-41-l-proline-CuCl] under mild conditions, yielding a variety of aryl chlorides in excellent yields. This method proved to be tolerant of a broad range of functional groups and particularly useful for the conversion of electron-deficient arylboronic acids to aryl chlorides, a transformation that is inefficient without copper catalysis. This heterogeneous copper catalyst can be recovered by a simple filtration of the reaction solution and recycled for at least 10 times without any decreases in activity.
- He, Wen,Zhang, Rongli,Cai, Mingzhong
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p. 764 - 770
(2017/01/13)
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- Electrophilic aryl-halogenation using N-halosuccinimides under ball-milling
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We report here a methodology of chemo- and regio-selective aryl bromination and iodination using respective N-halosuccinimides at room temperature in the absence of any solvents, catalyst/additives under ball-milling condition. However, for chlorination ceric ammonium nitrate was used as additive. The coupled product succinimide, produced from the reactions, was recycled via regeneration of NBS. This methodology works with the electron-donor substituted or unsubstituted arenes.
- Bose, Anima,Mal, Prasenjit
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supporting information
p. 2154 - 2156
(2015/03/18)
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- Aerobic oxidative bromination of arenes using an ionic liquid as both the catalyst and the solvent
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A method for the bromination of alkoxy-substituted benzenes and naphthalenes was developed by using the residual oxygen in the reaction tube as the oxidant, and [Bmim]NO3 (1-butyl-3-methylimidazolium nitrate) ionic liquid as both the catalyst and the solvent. No other reagent apart from the ionic liquid and molecular bromine was used in the reactions, and basically all the bromine atoms in the bromine source were transferred to the bromination products, showing that the presented protocol is highly atom economic and practical.
- Ren, Yun-Lai,Wang, Binyu,Tian, Xin-Zhe,Zhao, Shuang,Wang, Jianji
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supporting information
p. 6452 - 6455
(2015/11/16)
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- Electrophilic aryl-halogenation using N-halosuccinimides under ball-milling
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We report here a methodology of chemo- and regio-selective aryl bromination and iodination using respective N-halosuccinimides at room temperature in the absence of any solvents, catalyst/additives under ball-milling condition. However, for chlorination ceric ammonium nitrate was used as additive. The coupled product succinimide, produced from the reactions, was recycled via regeneration of NBS. This methodology works with the electron-donor substituted or unsubstituted arenes.
- Bose, Anima,Mal, Prasenjit
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supporting information
p. 2154 - 2156
(2014/04/03)
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- INHIBIT logic operations based on light-driven β-cyclodextrin pseudo[1]rotaxane with room temperature phosphorescence addresses
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INHIBIT logic gates based on light-driven β-cyclodextrin pseudo[1]rotaxane were conveniently fabricated in aqueous solution utilizing induced circular dichroism (ICD) and photocontrolled reversible room temperature phosphorescence (RTP) as output addresses respectively. The Royal Society of Chemistry 2014.
- Cao, Jingjing,Ma, Xiang,Min, Mingri,Cao, Tiantian,Wu, Shuaifan,Tian, He
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supporting information
p. 3224 - 3226
(2014/03/21)
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- Dinuclear Pd(i) complexes - Solely precatalysts? Demonstration of direct reactivity of a Pd(i) dimer with an aryl iodide
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This report provides experimental, computational and spectroscopic data in support of the direct reactivity of a Pd(i) dimer with an aryl iodide, resulting in Br/I halogen exchange between the complex and the aryl iodide. The reactivity could not be achieved through analogous Pd(0) conditions, demonstrating the distinct reactivities at such multiple Pd-sites. Computational studies support that the direct oxidative addition to ArI by the dinuclear metal complex is energetically feasible.
- Bonney, Karl J.,Proutiere, Fabien,Schoenebeck, Franziska
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p. 4434 - 4439
(2013/11/19)
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- A new recoverable Au(III) catalyst supported on magnetic polymer nanocomposite for aromatic bromination
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This Letter presents a facile alternative synthesis of a recoverable Au(III) catalyst supported on Fe3O4@SiO 2~MPS grafted by poly(N-vinyl-2-pyrrolidone) (PVP). The solid magnetic support was prepared by anchoring 3-methacryloxypropyltrimethoxysilane (MPS) onto the Fe3O4@SiO2 surfaces followed by free radical polymerization with N-vinyl-2-pyrrolidone. Au(III) was immobilized onto the magnetic support in aqueous media to afford Au(III)/Fe 3O4@SiO2~PVP (catalyst 1). Catalyst 1 was characterized by FT-IR, TEM, VSM, TGA, XRD, and ICP-AES. The amount of Au in catalyst 1 was measured to be 0.64 wt % by ICP-AES. This newly prepared catalyst can catalyze the aromatic bromination reaction with comparable activity as homogeneous AuCl3. Moreover, the supported catalyst is easy to recover and can be used in four cycles without apparent loss of activity.
- Li, Bai,Gao, Linfeng,Bian, Fengling,Yu, Wei
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supporting information
p. 1063 - 1066
(2013/04/10)
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- Synthesis, characterization, and catalytic activity of cationic NHC gold(III) pyridine complexes
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A series of cationic gold(I/III) pyridine complexes of the type [(L)Au(pyr)](PF6) and [(L)AuCl2(pyr)](PF6), where L = IPr, (1, 5); L = IMes (2, 6); L = ItBu, (3, 7); L = ICy (4, 8); and L = PPh3, (9, 10), were synthesized and characterized by NMR spectroscopy and single-crystal X-ray diffraction. The stability of the new complexes and their catalytic activity in five well-established organic transformations were assessed.
- Orbisaglia, Serena,Jacques, Beatrice,Braunstein, Pierre,Hueber, Damien,Pale, Patrick,Blanc, Aurelien,De Fremont, Pierre
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p. 4153 - 4164
(2013/09/02)
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- Halodeboronation of organotrifluoroborates using tetrabutylammonium tribromide or cesium triiodide
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Halodeboronation of organotrifluoroborates using commercially available tetrabutylammonium tribromide (TBATB) or cesium triiodide in aqueous medium is reported. The mild, transition metal-free method has proven to be tolerant of a wide range of functional groups. High regio- and chemoselectivity are observed. Two synthetic routes to (Z)-dibromoalkenes from alkynes, through stereodefined (Z)-2-bromoalkenyltrifluoroborates and (Z)-1,2-bis(boryl) alkenyltrifluoroborates, have been developed using the TBATB mediated bromodeboronation as the key step.
- Yao, Min-Liang,Kabalka, George W.,Blevins, David W.,Reddy, Marepally Srinivasa,Yong, Li
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experimental part
p. 3738 - 3743
(2012/06/30)
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- Silver catalyzed bromination of aromatics with N-bromosuccinimide
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A heterogeneous silver catalyst was prepared and applied efficiently for the selective bromination of aromatics with NBS. The silver nanoparticles combined with the acidic support HMB can activate both the aromatic ring and NBS, and the synergistic effects between the silver nanoparticles and the HMB highly enhanced the efficiency of the bromination reaction.
- Zhang, Rui,Huang, Lei,Zhang, Yanfang,Chen, Xiaorong,Xing, Weihong,Huang, Jun
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experimental part
p. 378 - 383
(2012/06/18)
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- Absorption and fluorescence spectroscopic properties of 1- and 1,4-silyl-substituted naphthalene derivatives
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Silyl-substituted naphthalene derivatives at the 1- and 1,4-positions were synthesized and their UV absorption, fluorescence spectroscopic properties, and fluorescence lifetimes were determined. Analysis of the results shows that the introduction of silyl groups at these positions of the naphthalene chromophore/fluorophore causes shifts of the absorption maxima to longer wavelengths and increases in fluorescence intensities. Bathochromic shifts of the absorption maxima and increases in fluorescence intensities are also promoted by the introduction of methoxy and cyano groups at the naphthalene 4- and 5-positions. In addition, the fluorescence of 9,10-dicyanoanthracene is efficiently quenched by these naphthalene derivatives with Stern-Volmer plot calculated rate constants that depend on the steric bulk of the silyl groups.
- Maeda, Hajime,Maeda, Tomohiro,Mizuno, Kazuhiko
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experimental part
p. 5108 - 5125
(2012/08/28)
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- Bromination of aromatic compounds using an Fe2O 3/zeolite catalyst
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The catalytic bromination of non-activated aromatic compounds has been achieved using an Fe2O3/zeolite catalyst system. FeBr 3 was identified as the catalytic species, formed in situ from HBr and Fe2O3. The catalyst was easy-to-handle and cost effective and could also be recycled. The reaction system was also amenable to the one-pot sequential bromination/C-C bond formation of benzene.
- Nishina, Yuta,Takami, Keishi
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supporting information
p. 2380 - 2383
(2013/02/21)
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- Aromatic substitution in ball mills: Formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
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Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed. The Royal Society of Chemistry.
- Schmidt, Robert,Stolle, Achim,Ondruschka, Bernd
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p. 1673 - 1679
(2013/02/22)
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- Nucleophilic substitution of hydrogen in naphthalene by chloride (Cl -) in ionic liquids
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Nucleophilic aromatic substitution of hydrogen in non-activated aromatic ring, a very rare phenomenon in organic chemistry, is found in ionic liquids containing Cl- as anion under mild reaction conditions. The reaction may be carried out by the addition of the halogen-bonding adduct (Br 2Cl-) as nucleophile to aromatic ring carbon atom, leading to the formation of the nucleophilic substitution product.
- Shi, Shen Yi,Kong, Ai Guo,Zhao, Xin Hua,Ding, Han Ming,Yang, Fan,Shan, Yong Kui
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scheme or table
p. 147 - 150
(2012/01/03)
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- Synthesis of uniformly 13C-labeled polycyclic aromatic hydrocarbons
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Convergent synthetic pathways were devised for efficient synthesis of a series of uniformly 13C labeled polycyclic aromatic hydrocarbons de novo from U-13C-benzene and other simple commercially-available 13C-starting compounds. All target products were obtained in excellent yields, including the alternant PAH U-13C-naphthalene, U-13C-phenanthrene, U-13C-anthracene, U- 13C-benz[a]anthracene, U-13C-pyrene and the nonalternant PAH U-13C-fluoranthene.
- Zhang, Zhenfa,Sangaiah, Ramiah,Gold, Avram,Ball, Louise M.
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p. 5431 - 5435
(2011/09/14)
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- Photocontrolled reversible room temperature phosphorescence (RTP) encoding β-cyclodextrin pseudorotaxane
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Photocontrolled reversible room temperature phosphorescence (RTP) emission engendered by the complexation of β-cyclodextrin (β-CD) and α-bromonaphthalene (α-BrNp) can be employed to address the threading and dethreading of the pseudorotaxane formed between β-CD and sodium 2-hydroxy-5-((4-nitrophenyl)diazenyl)benzoate (DAYR) in the ternary system in aqueous solution.
- Ma, Xiang,Cao, Jingjing,Wang, Qiaochun,Tian, He
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supporting information; body text
p. 3559 - 3561
(2011/05/12)
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- Gold-catalyzed halogenation of aromatics by N-halosuccinimides
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(Chemical Equation Presented) Golden bromination: A highly efficient and mild AuCl3-catalyzed bromination of aromatic rings with Nbromosuccinimide (NBS) has been developed. This method works with a low catalyst loading (down to 0.01 mol %) and can be combined with transition metal catalyzed transformations to deliver various aryl products.
- Mo, Fanyang,Yan, Jerry Mingtao,Qiu, Di,Li, Fei,Zhang, Yan,Wang, Jianbo
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scheme or table
p. 2028 - 2032
(2010/06/17)
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- Oxidative bromination reaction using Cu2+- perfluorophthalocyanine-immobilized silica gel catalyst under mild reaction conditions
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A simplified, facile route has been applied for the grafting of copper(II) perfluorophthalocyanine complex onto functionalized silica gel. The resulting organic-inorganic hybrid material is used as an efficient and recyclable catalyst for the regioselective oxidative bromination of various aromatic substrates using KBr/H2O2 as the reagents, affording high yields under mild conditions. High catalytic activity efficiency could be attributed to the heterogenization of soluble metal complexes on the high surface area host.
- Sharma,Sharma, Chetna
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experimental part
p. 4415 - 4418
(2010/09/20)
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- Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
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A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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experimental part
p. 4429 - 4439
(2009/10/09)
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- Direct halogenation of organic compounds with halides using oxone in water - A green protocol
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Direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·KHSO4·K 2S04) in water was accomplished successfully in high-to-excellent yields. The main benefit of this protocol is the performance of the reactions in water in the presence of a harmless oxidant without the use of any organic cosolvents. Using NaBr and NaI as the safe sources of halogens is another advantage of the protocol. This method is easily applicable to the large-scale operations. We have also applied this method successfully for the iodocyclization of an unsaturated alcohol and an unsaturated carboxylic acid.
- Firouzabadi,Iranpoor,Kazemi
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experimental part
p. 1675 - 1681
(2010/01/29)
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- A new method of bromination of aromatic rings by an iso-amyl nitrite/HBr system
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A mixture of iso-amyl nitrite/HBr is shown to be a mild and efficient reagent for electrophilic aromatic bromination. The reaction succeeds with slightly activated arenes and heterocyclic compounds. By using HCl instead of HBr, chlorination can also be performed in few cases. The i-amONO2/HBr mixture can also be utilized for bromination in the α-position of electron withdrawing groups. A possible mechanism is briefly discussed.
- Gavara, Laurent,Boisse, Thomas,Rigo, Beno?t,Hénichart, Jean-Pierre
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p. 4999 - 5004
(2008/09/21)
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- The role of neat substrates in phase-vanishing and tandem phase-vanishing reactions
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Phase-vanishing reactions are triphasic reactions, which involve a reagent, a liquid perfluoroalkane as a phase screen and a substrate. Aromatization, isomerization and halogenation of neat substrates under phase-vanishing conditions gave the expected products in good to excellent yields. In tandem single-phase-phase-vanishing reaction, two reactants, placed in the top phase, afforded the intermediate, which in a subsequent phase-vanishing reaction reacted with the reagent from the bottom phase to give the final product. The reaction worked well under solvent-free conditions on liquid substrates and intermediates. With solids, results were better if an additional solvent was employed.
- Windmon, Nicole,Dragojlovic, Veljko
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scheme or table
p. 6543 - 6546
(2009/04/06)
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- Organic glass-forming materials: 1,3,5-Tris(naphthyl)benzene derivatives
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(Chemical Equation Presented) The organic glass-forming materials 1,3-bis(1-naphthyl)-5-(2-naphthyl)benzene (2) and its partially deuterated analogue, 1,3-bis(1-naphthyl-d7)-5-(2-naphthyl)benzene (2-d 14), have been synthesized on a gram scale using Suzuki coupling reactions. Detailed spectroscopic studies afford complete NMR assignments ( 1H, 2H, 13C) for both compounds. Modest energy barriers for the interconversion of atropisomers (ca. 15 kcal/mol) result in a propensity for these materials to form supercooled liquids and glasses, rather than undergoing crystallization. The preparation of these materials enables detailed studies of physical properties of organic glasses and molecular diffusion in condensed phases.
- Bonvallet, Paul A.,Breitkreuz, Caroline J.,Yong, Seol Kim,Todd, Eric M.,Traynor, Katherine,Fry, Charles G.,Ediger,McMahon, Robert J.
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p. 10051 - 10057
(2008/04/05)
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- Green synthesis of tetraalkylammonium tribromide using cerium(IV) ammonium nitrate (CAN) as oxidant
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Cerium(IV) ammonium nitrate (CAN) mediates oxidation of tetraalkylammonium bromide to tetraalkylammonium tribromide in greener reaction conditions using water as solvent. The procedure is simple, convenient, and environmentally benign for the synthesis of tetraalkylammonium tribromide with great yields. Copyright Taylor & Francis Group, LLC.
- Borah, Ruli,Thakur, Ashim Jyoti
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p. 933 - 939
(2007/10/03)
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- Catalytic Sandmeyer bromination
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An efficient catalyst system for Sandmeyer bromination is proposed. Aryl bromides and dibromides can be obtained with excellent yield by this synthetic protocol. Georg Thieme Verlag Stuttgart.
- Beletskaya, Irina P.,Sigeev, Alexander S.,Peregudov, Alexander S.,Petrovskii, Pavel V.
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p. 2534 - 2538
(2008/03/13)
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- PROCESS FOR SYNTHESIS OF AROMATIC COMPOUNDS
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The present invention refers to a process for preparing a compound of the formula (I) wherein R denotes an organic radical which, together with the two carbon atoms to which it is bonded, forms a carbocyclic or heterocyclic ring; R1, R2, R3 and X, independently, denote hydrogen, halogen, nitro, cyano or an organic radical; or R1 and R2 or R2 and R3, together with the carbon atoms to which they are bonded, form a ring; which comprises exposing a compound of the formula (II) wherein R1, R2, R3 and X are defined as given above and Y and Z, independently, have one of the meanings of X; to an energy source in the presence of a catalyst system.
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Page/Page column 17
(2008/06/13)
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- Sodium nitrite-catalyzed oxybromination of aromatic compounds and aryl ketones with a combination of hydrobromic acid and molecular oxygen under mild conditions
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A novel and efficient catalytic system for the oxybromination of aromatic compounds and aryl ketones utilizing a combination of aqueous hydrobromic acid and molecular oxygen in the presence of sodium nitrite under mild conditions has been developed. The newly developed catalytic system utilizes cheap and readily available reactants, exhibits high bromine atom economy and releases only innocuous water as the by-product.
- Zhang, Guofu,Liu, Renhua,Xu, Qing,Ma, Lixin,Liang, Xinmiao
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p. 862 - 866
(2007/10/03)
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- Efficient one-pot transformation of aminoarenes to haloarenes using halodimethylisulfonium halides generated in situ
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Halodimethylsulfonium halide 1, which is readily formed in situ from hydrohaloic acid and DMSO, is a good nucleophilic halide. This activated nucleophilic halide rapidly converts aryldiazonium salt prepared in situ by the same hydrohaloic acid and nitrite ion to aryl chlorides, bromides, or iodides in good yield. The combined action of nitrite ion and hydrohaloic acid in DMSO is required for the direct transformation of aromatic amines, which results in the production of aryl halides within 1 h. Substituted compounds with electron-donating or -withdrawing groups or sterically hindered aromatic amines are also smoothly transformed to the corresponding aromatic halides. The only observed by-product is the deaminated arene (usually 7%). The isolated aryldiazonium salts can also be converted to the corresponding aryl halides using 1. The present method offers a facile, one-step procedure for transforming aminoarenes to haloarenes and lacks the environmental pollutants that usually accompany the Sandmeyer reaction using copper halides.
- Baik, Woonphil,Luan, Wanqiang,Lee, Hyun Joo,Yoon, Cheol Hun,Koo, Sangho,Kim, Byeong Hyo
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p. 213 - 219
(2007/10/03)
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- A new method for the oxybromination of aromatic compounds with copper(II)bromide and potassium dichromate
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A new and mild method for oxybromination of aromatic compounds with CuBr2 and K2Cr2O7 in HOAC is reported. Copyright Taylor & Francis Inc.
- Badri, Rashid,Shushizadeh, Mohammad Reza
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p. 533 - 536
(2007/10/03)
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- Regioselective synthesis of para-bromo aromatic compounds
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Reaction of substituted benzenerings with N-bromophthalimide, underneutral conditions, gave the corresponding bromo derivatives with a preference for the formation of the para bromoisomer over the ortho isomer. The sim pie work-up procedure minimizes loss of product and the yields are good.
- Khazaei, Ardeshir,Manesh, Abbas Amini,Safi, Vahid Reza
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p. 559 - 562
(2007/10/03)
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- The conversion of phenols to the corresponding aryl halides under mild conditions
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Mild, novel procedures have been developed for the syntheses of aryl halides from the corresponding phenols in modest to good yields via boronate ester intermediates.
- Thompson, Alicia L. S.,Kabalka, George W.,Akula, Murthy R.,Huffman, John W.
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p. 547 - 550
(2007/10/03)
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- Regioselective haloaromatization of 1,2-bis(ethynyl)benzene via halogen acids and PtCl2. Platinum-catalyzed 6-π electrocyclization of 1,2-bis(1′-haloethenyl)benzene intermediates
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Treatment of 1,2-bis(ethynyl)benzene (1) with aqueous HX (X = Br, I) in hot 3-pentanone (100-105 °C, 2 h) afforded 1,2-bis(1′-haloethenyl)benzene species 2-Br and 2-I in 98% and 95% yields, respectively. The hydrochlorination of endiyne 1 failed to proceed at elevated temperature but was implemented efficiently by PtCl2 (5 mol %) in hot 3-pentanone (100 °C, 2 h) to give 1,2-bis(1′-chloroetheny)benzene 2-Cl in 80% yield. In the presence of PtCl2 (5 mol %), these halides 2-Cl, 2-Br, and 2-I were subsequently converted to 1-halonaphthalenes 3-Cl, 3-Br, and 3-I in the mother solution via sequential 6-π electrocyclization and dehalogenation reactions. PtCl2 (5 mol %) also effected direct haloaromatization of endiyne 1 with HX (X = Cl, Br, I) and gave 1-halonaphthalenes 3-Cl, 3-Br, and 3-I in 64-71% yields. This investigation reports the scope and the regioselectivity of haloaromatization of various enediynes catalyzed by PtCl2.
- Lo, Ching-Yu,Kumar, Manyam Praveen,Chang, Hsu-Kai,Lush, Shie-Fu,Liu, Rai-Shung
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p. 10482 - 10487
(2007/10/03)
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- Paradigm confirmed: The first use of ionic liquids to dramatically influence the outcome of chemical reactions
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It has been an unproven paradigm that the choice of which ionic liquid to use in a chemical reaction can have a dramatic effect on the outcome of that chemical reaction. We demonstrate, for the first time, that the reaction of toluene and nitric acid in three different ionic liquids gives rise to three completely different products in high yield. Furthermore, ionic liquids can catalyze these reactions with the only byproduct being water.
- Earle, Martyn J.,Katdare, Suhas P.,Seddon, Kenneth R.
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p. 707 - 710
(2007/10/03)
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