- Gold-Catalyzed Tandem Oxidative Coupling Reaction between β-Ketoallenes and Electron-Rich Arenes to 2-Furylmethylarenes
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A tandem oxidative coupling reaction of β-ketoallenes and arenes was developed, which leads to the formation of 2-furylmethylarenes using AuCl3 and phenyliodine diacetate. The AuIII salt catalyzed the cyclization of β-ketoallenes to form a 2-furylmethyl gold intermediate, and the subsequent C-H functionalization of arenes proceeded smoothly. During the oxidative coupling, nucleophilic additions occurred at the center and terminal carbon atoms of the allene moiety to form C-O and C-C bonds.
- Yasukawa, Naoki,Yamada, Yutaro,Furugen, Chikara,Miki, Yuya,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 5891 - 5895
(2021/08/18)
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- Sulfoxide-Promoted Chlorination of Indoles and Electron-Rich Arenes with Chlorine as Nucleophile
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An efficient chlorination of indoles and electron-rich arenes with chlorine anion as nucleophile is described. With the use of ethyl phenyl sulfoxide as the promoter, the reaction went smoothly under metal-free and mild conditions. Various indoles and electron-rich arenes are converted into the corresponding chlorinated compounds in moderate to excellent yields. A plausible interrupted Pummerer reaction mechanism was proposed without the oxidation of chloride anion. In addition, the byproduct thioether could be easily converted to the starting material sulfoxide just by a simple oxidation reaction. (Figure presented.).
- Ji, Yuan-Zhao,Li, Hui-Jing,Wang, Yi-Ruo,Wu, Yan-Chao,Zhang, Zheng-Yan
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supporting information
(2020/02/05)
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- Oxidative Photochlorination of Electron-Rich Arenes via in situ Bromination
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Electron-rich arenes are oxidatively photochlorinated in the presence of catalytic amounts of bromide ions, visible light, and 4CzIPN as organic photoredox catalyst. The substrates are brominated in situ in a first photoredox-catalyzed oxidation step, followed by a photocatalyzed ipso-chlorination, yielding the target compounds in high ortho/para regioselectivity. Dioxygen serves as a green and convenient terminal oxidant. The use of aqueous hydrochloric acid as the chloride source reduces the amount of saline by-products.
- Düsel, Simon Josef Siegfried,K?nig, Burkhard
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supporting information
p. 1491 - 1495
(2019/04/30)
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- In situ Generation of Hypervalent Iodine Reagents for the Electrophilic Chlorination of Arenes
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Efficient metal-free methods for the electrophilic chlorination of arenes using PIFA and simple chlorine sources are reported. The in situ formation of PhI(Cl)OCOCF3 from PIFA and KCl is proposed, which resulted in a chlorinating species for moderately activated arenes. Moreover, the in situ formation of PhICl2 from PIFA and TMSCl resulted in an excellent approach for the chlorination of a great variety of arenes (20 examples) in high yields, even when working on a multigram scale.
- Granados, Albert,Jia, Zhiyu,del Olmo, Marc,Vallribera, Adelina
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p. 2812 - 2818
(2019/04/08)
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- Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes
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Photoexcited electron-hole pairs on a semiconductor surface can engage in redox reactions with two different substrates. Similar to conventional electrosynthesis, the primary redox intermediates afford only separate oxidized and reduced products or, more rarely, combine to one addition product. Here, we report that a stable organic semiconductor material, mesoporous graphitic carbon nitride (mpg-CN), can act as a visible-light photoredox catalyst to orchestrate oxidative and reductive interfacial electron transfers to two different substrates in a two- or three-component system for direct twofold carbon–hydrogen functionalization of arenes and heteroarenes. The mpg-CN catalyst tolerates reactive radicals and strong nucleophiles, is straightforwardly recoverable by simple centrifugation of reaction mixtures, and is reusable for at least four catalytic transformations with conserved activity.
- Ghosh, Indrajit,Khamrai, Jagadish,Savateev, Aleksandr,Shlapakov, Nikita,Antonietti, Markus,K?nig, Burkhard
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p. 360 - 366
(2019/08/15)
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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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- Preparation, Characterization and Reactivity of a Bis-hypochlorite Adduct of a Chiral Manganese(IV) Salen Complex
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A bis-hypochlorite adduct of a manganese(IV) salen complex having a chiral (R,R)-cyclohexane-1,2-diamine linkage (2-tBu) is successfully prepared and characterized by various spectroscopic methods. The reactions of 2-tBu with various organic substrates show that 2-tBu is capable of sulfoxidation, epoxidation, chlorination, and hydrogen abstraction reactions. However, the enantioselectivity of the epoxidation reactions by 2-tBu is much lower than that reported for the catalytic reactions by Jacobsen's catalyst. The low enantioselectivity is consistent with a planar conformation of the salen ligand, which is suggested by circular dichroism spectroscopy. This study suggests that 2-tBu is not a reactive intermediate of Jacobsen's enantioselective epoxidation catalysis.
- Araki, Ikuko,Fukui, Kaoru,Fujii, Hiroshi
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supporting information
p. 1685 - 1688
(2018/02/27)
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- Atom-Economic Electron Donors for Photobiocatalytic Halogenations
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In vitro cofactor supply and regeneration have been a major obstacle for biocatalytic processes, in particular on a large scale. Peroxidases often suffer from inactivation by their oxidative co-factor. Combining photocatalysis and biocatalysis offers an innovative solution to this problem, but lacks atom economy due to the sacrificial electron donors needed. Herein, we show that redox-active buffers or even water alone can serve as efficient, biocompatible electron sources, when combined with photocatalysis. Mechanistic investigations revealed first insights into the possibilities and limitations of this approach and allowed adjusting the reaction conditions to the specific needs of biocatalytic transformations. Proof-of-concept for the applicability of this photobiocatalytic reaction setup was given by enzymatic halogenations.
- Seel, Catharina Julia,Králík, Antonín,Hacker, Melanie,Frank, Annika,K?nig, Burkhard,Gulder, Tanja
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p. 3960 - 3963
(2018/09/25)
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- Transition metal-free protodecarboxylation of electron rich aromatic acids under mild conditions
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A mild and practical method for the transition metal-free protodecarboxylation of aromatic acids using readily available and safe sodium persulfate as initiator was described. This environment-friendly decarboxylation approach was performed at 60 °C in ethanol and could easily scale up to the gram level with a good yield. In Particular, the tandem reactions of decarboxylation and halogenation were achieved by the addition of the corresponding halogenating reagents to the reaction system.
- Fang, Jingxian,Wang, Dangui,Deng, Guo-Jun,Gong, Hang
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p. 4503 - 4506
(2017/10/30)
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- Decarboxylative Halogenation and Cyanation of Electron-Deficient Aryl Carboxylic Acids via Cu Mediator as Well as Electron-Rich Ones through Pd Catalyst under Aerobic Conditions
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Simple strategies for decarboxylative functionalizations of electron-deficient benzoic acids via using Cu(I) as promoter and electron-rich ones by employing Pd(II) as catalyst under aerobic conditions have been established, which lead to smooth synthesis of aryl halides (-I, Br, and Cl) through the decarboxylative functionalization of benzoic acids with readily available halogen sources CuX (X = I, Br, Cl), and easy preparation of benzonitriles from decarboxylative cyanation of aryl carboxylic acids with nontoxic and low-cost K4Fe(CN)6 under an oxygen atmosphere for the first time.
- Fu, Zhengjiang,Li, Zhaojie,Song, Yuanyuan,Yang, Ruchun,Liu, Yanzhu,Cai, Hu
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p. 2794 - 2803
(2016/04/26)
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- Effective bromo and chloro peroxidation catalysed by tungsten(vi) amino triphenolate complexes
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Amino triphenolate tungsten(vi) complexes have been prepared and they proved to be efficient catalysts in haloperoxidation reactions using hydrogen peroxide as a terminal oxidant and inorganic sources of halides. In particular, interesting results have been obtained in the challenging chloroperoxidation reactivity (catalyst loading down to 0.05% with TONs up to 900). A comparison among three different metal complexes bearing the same ligand (vanadium(v), molybdenum(vi) and tungsten(vi)) showed much better performances of the last complex both on bromo and chloro peroxidations.
- Badetti, Elena,Romano, Francesco,Marchiò, Luciano,Ta?kesenlio?lu, Sara,Da?tan, Arif,Zonta, Cristiano,Licini, Giulia
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p. 14603 - 14608
(2016/09/28)
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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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p. 2154 - 2156
(2015/03/18)
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- Para-Selective Halogenation of Nitrosoarenes with Copper(II) Halides
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The para-selective direct bromination and chlorination of nitrosoarenes with copper(II) bromide and chloride is reported. Under mild reaction conditions, a range of halogenated arylnitroso compounds are obtained in moderate to good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of a one-pot procedure to obtain the corresponding para-halogenated aniline- and nitrobenzene derivatives.
- Van Der Werf, Angela,Selander, Nicklas
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supporting information
p. 6210 - 6213
(2016/01/09)
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- Nitrogen-centered radical-mediated C-H imidation of arenes and heteroarenes via visible light induced photocatalysis
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The C-H imidation of arenes and heteroarenes has been achieved via visible light induced photocatalysis. In the presence of an iridium(iii) photoredox catalyst, the reaction of aromatic substrates with N-chlorophthalimide furnishes the N-aryl products at room temperature through a nitrogen-centered radical mediated aromatic substitution.
- Kim, Hyejin,Kim, Taehoon,Lee, Dong Gil,Roh, Sang Weon,Lee, Chulbom
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supporting information
p. 9273 - 9276
(2014/08/05)
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- Practical and metal-free electrophilic aromatic halogenation by interhalogen compounds generated in situ from N-halosuccinimide and catalytic TMSCL
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Halomonochloride compounds (ClCl, BrCl, ICl) generated in situ from N-halosuccinimide and catalytic chlorotrimethylsilane (TMSCl, 0.1 equiv) can efficiently halogenate aromatic compounds to give halogenated products in good to excellent yields and selectivities. The reaction can be carried out at room temperature or at lower temperatures, requires only one hour, is practical to apply to a wide range of substrates, and provides a simple access to a variety of haloarene compounds. Georg Thieme Verlag Stuttgart New York.
- Maibunkaew, Tapanee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Bunrit, Anon,Ruchirawat, Somsak
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supporting information
p. 1769 - 1775
(2014/08/05)
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- Electrophilic aryl-halogenation using N-halosuccinimides under ball-milling
-
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
-
supporting information
p. 2154 - 2156
(2014/04/03)
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- Catalytic electrophilic halogenations and haloalkoxylations by non-heme iron halides
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Synthetic non-heme iron halides promote sub-stoichiometric aliphatic halogenation reactions via a radical mechanism. Complementary to such activity, we have developed an electrophilic halogenation of arenes employing non-heme iron halides. A catalytic version of these reactions has also been developed using potassium halide as the source of halogen atom for arenes at room temperature. Efforts towards understanding the mechanism of these catalytic halogenation reactions led to the discovery of the haloalkoxylation of olefins by a non-heme iron complex. Implications of these findings with respect to natural transformations are also discussed.
- Rana, Sujoy,Bag, Sukdev,Patra, Tuhin,Maiti, Debabrata
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supporting information
p. 2453 - 2458
(2014/09/30)
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- Pd(II)-catalyzed bromo- and chlorodecarboxylation of electron-rich arenecarboxylic acids
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A bromo- and chlorodecarboxylation of various aromatic carboxylic acids catalyzed by Pd(II) has been developed in this work. A series of electron-rich arenecarboxylic acids gave the corresponding decarboxylative monohalogenation products under the typical reaction conditions.
- Peng, Xuefeng,Shao, Xiang-Feng,Liu, Zhong-Quan
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supporting information
p. 3079 - 3081
(2013/07/11)
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- An efficient chlorination of aromatic compounds using a catalytic amount of iodobenzene
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An efficient method was developed for chlorination of aromatic compounds with electron-donating groups using iodobenzene as the catalyst and m-chloroperbenzoic acid as the terminal oxidant in the presence of 4-methylbenzenesulfonic acid in THF at room temperature for 24 h, and a series of the monochlorinated compounds was obtained in good yields. In this protocol, the catalyst iodobenzene was first oxidized into the hypervalent iodine intermediate, which then treated with lithium chloride and finally reacted with aromatic compounds to form the chlorinated compounds.
- Li, Ting-Ting,Xu, Cui,Xiang, Chang-Bin,Yan, Jie
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p. 535 - 538
(2013/07/27)
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- Oxygenation and chlorination of aromatic hydrocarbons with hydrochloric acid photosensitized by 9-mesityl-10-methylacridinium under visible light irradiation
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Efficient photocatalytic oxygenation of toluene occurs under visible light irradiation of 9-mesityl-10-methylacridinium (Acr+-Mes) in oxygen-saturated acetonitrile containing toluene and aqueous hydrochloric acid with a xenon lamp for 15 h. The oxygenated products, benzoic acid (70 %) and benzaldehyde (30 %), were formed after the photoirradiation. The photocatalytic reaction is initiated by intramolecular photoinduced electron transfer from the mesitylene moiety to the singlet excited state of the Acr+ moiety of Acr+-Mes, which affords the electron-transfer state, Acr ?-Mes?+. The Mes?+ moiety can oxidize chloride ion (Cl-) by electron transfer to produce chlorine radical (Cl?), whereas the Acr? moiety can reduce O2 to O 2 ?-. The Cl ? radical produced abstracts a hydrogen from toluene to afford benzyl radical in competition with the bimolecular radical coupling of Cl ?. The benzyl radical reacts with O2 rapidly to afford the peroxyl radical, leading to the oxygenated product, benzaldehyde. Benzaldehyde is readily further photooxygenated to yield benzoic acid with Acr?-Mes?+. In the case of an aromatic compound with electron-donating substituents, 1,3,5-trimethoxybenzene, photocatalytic chlorination occurred efficiently under the same photoirradiation conditions to yield a monochloro-substituted compound, 2,4,6-trimethoxychlorobenzene.
- Ohkubo, Kei,Mizushima, Kentaro,Fukuzumi, Shunichi
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p. 205 - 220
(2013/03/13)
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- Efficient oxidative chlorination of aromatics on saturated sodium chloride solution
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An efficient metal-free system using saturated aqueous sodium chloride/aqueous ammonium chloride solution as chlorine source and potassium persulfate as a cheap oxidant for the chlorination of various aromatic compounds including deactivated ones has been developed that proceeds without any acid additive in an excellent regioselective manner. The easy-to-handle aqueous solution/acetonitrile biphasic system as solvent and no need for precautionary measures make this process very practical. Copyright
- Gu, Liuqun,Lu, Ting,Zhang, Mingyun,Tou, Lijuan,Zhang, Yugen
-
supporting information
p. 1077 - 1082
(2013/05/21)
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- Formation of iron(III) meso-chloro-isoporphyrin as a reactive chlorinating agent from oxoiron(IV) porphyrin π-cation radical
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Iron(III) isoporphyrin, a tautomer of porphyrin with a saturated meso carbon, is one of the isoelectronic forms of oxoiron(IV) porphyrin π-cation radical, which is known as an important reactive intermediate of various heme enzymes. The isoporphyrin has been believed to be incapable of catalyzing oxygenation and oxidation reactions. Here, we report that an oxoiron(IV) porphyrin π-cation radical can be converted to iron(III) meso-chloro- isoporphyrin in the presence of trifluoroacetic acid and chloride ion. More importantly, this study shows the first evidence that iron(III) meso-chloro-isoporphyrin is an excellent reactive agent for chlorinating aromatic compounds and olefins. The results of this study suggest that the mechanism involves electrophilic chlorination of substrate with iron(III) meso-chloro-isoporphyrin.
- Cong, Zhiqi,Kurahashi, Takuya,Fujii, Hiroshi
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supporting information; experimental part
p. 4469 - 4472
(2012/04/23)
-
- Oxidative functional group transformations with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
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A divanadium-substituted phosphotungstate TBA4[γ-PW 10O38V2(μ-OH)(μ-O)] (I, TBA = tetra-n-butylammonium) reacts with one equivalent H+ to form a bis-μ-hydroxo species [γ-PW10O38V 2(μ-OH)2]3- (I′) in organic media. The strong electrophilic oxidants such as [γ-PW10O 38V2(μ-OH)(μ-OOH)]3- (II) and [γ-PW10O38V2(μ-η2: η2-O2)]3- (III) are formed by the reaction of the bis-μ-hydroxo species with H2O2. In the presence of I and H+, H2O2-based oxidations such as (i) epoxidation of alkenes (17 examples including electron-deficient ones), (ii) hydroxylation of alkanes (11 examples), and (iii) oxidative bromination of alkenes, alkynes, and aromatics with Br- as a bromo source (12 examples including chlorination) chemo-, diastereo-, and regioselectively proceed to give the corresponding oxidized products in moderate to high yields with high efficiencies of H2O2 utilization.
- Mizuno, Noritaka,Kamata, Keigo,Yamaguchi, Kazuya
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scheme or table
p. 157 - 161
(2012/06/18)
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- Synthesis, characterization, and reactivity of hypochloritoiron(III) porphyrin complexes
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A hypochloritoiron(III) porphyrin species has been proposed as a key intermediate in an antimicrobial defense system in neutrophils and in heme-catalyzed chlorination reactions. We report herein the preparation, spectroscopic characterization, and reactiv
- Cong, Zhiqi,Yanagisawa, Sachiko,Kurahashi, Takuya,Ogura, Takashi,Nakashima, Satoru,Fujii, Hiroshi
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supporting information
p. 20617 - 20620
(2013/02/23)
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- An efficient H2O2-based oxidative bromination of alkenes, alkynes, and aromatics by a divanadium-substituted phosphotungstate
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A divanadium-substituted phosphotungstate TBA4[γ-HPV 2W10O40] (TBA = tetra-n-butylammonium) could act as an effective homogeneous catalyst for the H2O 2-based oxidative bromination.
- Yonehara, Kazuhiro,Kamata, Keigo,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information; scheme or table
p. 1692 - 1694
(2011/03/22)
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- Oxidation of chloride and subsequent chlorination of organic compounds by oxoiron(IV) porphyrin π-cation radicals
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Ironing it out: Oxoiron(IV) porphyrin π-cation radical complexes (see figure) serve as models for the oxidation of Cl- into an active chlorinating reagent that chlorinates various organic compounds. Evidence suggests that Cl- is oxidized to Cl2 via Cl.. The mechanism involving either direct electron transfer or iron(III) hypochlorite formation, and then homolysis of the Cl-O bond is discussed. Copyright
- Cong, Zhiqi,Kurahashi, Takuya,Fujii, Hiroshi
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experimental part
p. 9935 - 9939
(2011/12/13)
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- Molybdenum(VI) amino triphenolate complexes as catalysts for sulfoxidation, epoxidation and haloperoxidation
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Two molybdenum(VI) complexes bearing a C3 symmetrical amino tris-tert-butylphenolate ligand have proved to be air- and water-tolerant catalysts that efficiently catalyse, in high yields and selectivity, the oxidation of sulfides, olefins and halides. In particular high turnover frequencies and turnover numbers (TOF and TON) have been obtained for the cyclooctene epoxidation (catalyst loading down to 0.05%, TONs up to 88,000 and TOFs up to 7500h-1). Copyright
- Romano, Francesco,Linden, Anthony,Mba, Miriam,Zonta, Cristiano,Licini, Giulia
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scheme or table
p. 2937 - 2942
(2011/01/05)
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- Regioselective copper-catalyzed chlorination and bromination of arenes with O2 as the oxidant
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Electron-rich aromatic C-H bonds undergo regioselective chlorination and bromination in the presence of CuX2, LiX (X = Cl, Br) and molecular oxygen. Preliminary mechanistic insights suggest that the bromination and chlorination reactions proceed by different pathways.
- Yang, Lujuan,Lu, Zhan,Stahl, Shannon S.
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supporting information; experimental part
p. 6460 - 6462
(2010/03/04)
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- Preparative and Structural Chemistry of Diastereomeric Derivatives of 3-PhosphanylpyrroIidine and Their Palladium(II) Complexes -Asymmetric Grignard Cross-Coupling Reaction
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The preparation of both diastereomeric derivatives of 3-(diphenylphosphanyljpyrrolidine with chiral (tetrahydrofuran2-yl}methyl and [(/V-neopentyl)pyrrolidin-2-yl]methyl groups as substituents on the pyrrolidine nitrogen atom and of (2S,4S)-l-benzyl-4-(diphenylphosphanyl)-2-(methoxymethyljpyrrolidine is reported. [3S,P(fiS)]-3-(phenylphosphanyljpyrrolidine, bearing an additional chiral center on phosphorus, is the starting material for the preparation of phosphanes, in which one phenyl group of the PPh2 moiety is substituted by an 2-methoxyphenyl (= An) or 2,4,6-trimethoxyphenyl (= TMP) group. PdI2 complexes of these ligands were separated into diastereomers by chromatography on silica gel columns. The structural chemistry of these novel phosphane diastereomers and their PdI2 complexes is investigated by X-ray crystallography and NMR. At the P,N-coordinated palladium center displacement of an iodide anion is found for P,N,N' ligands only. In the nickel complex catalysed cross-coupling reaction, yielding 3-phenyl-l-butene, we obtain the highest enantioselectivities in the case of simple l-alkyl-3-(diphenylphosphanyl)pyrrolidine ligands. The enantioselectivity obtained with diastereomeric derivatives, bearing additional ether or amine ligating sites is mainly determined by the chiral center in 3-position of the 3-(phosphanyl)pyrrolidine part of these ligands. Optimisation of enantioselectivity with these ligands can be carried out by a variation of the ligand to nickel ratio and by the choice of the vinyl halide used as starting compound. The catalytic cycle must contain at least one catalytically active species, bearing more than one ss-aminoalkylphosphane ligand. VCH Verlagsgesellschaft mbH,.
- Nagel, Ulrich,Nedden, Hans Guenter
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p. 989 - 1006
(2007/10/03)
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- Selective aromatic chlorination of activated arenes with sodium chlorite, (salen)manganese(III) complex, and alumina in dichloromethane
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The reaction of alkyl phenyl ethers with sodium chlorite in dichloromethane in the presence of a (salen)manganese(III) complex and alumina preloaded with a small amount of water afforded monochlorination products with unusually high para selectivities under mild conditions. The NaClO2-based biphasic system can also be successfully used for the regioselective monochlorination of substituted anisoles and polymethoxybenzenes.
- Hirano,Yakabe,Monobe,Morimoto
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p. 1905 - 1912
(2007/10/03)
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- Chlorosulfination of Aromatic Methyl Ethers with Thionyl Chloride
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Aromatic sulfinyl chlorides have been prepared in high yield by direct chlorosulfination of some aromatic ethers (1,3-dimethoxybenzene, 2,-methyl- and 4-chloro-1,3-dimethoxybenzene, 1,2,3-trimethoxybenzene, 1- and 2-methoxynaphthalene, 1,5-,1,7-,2,6-and 2,7-dimethoxynaphtalene) with thionyl chloride alone at or below room temperature.Under the same conditions, 1,4-dimethoxynaphthalene and 1,3-dimethoxy-5-methylbenzene yield chlorinated starting materials and sulfides. 1,3,5-Trimethoxybenzene yields chlorinated starting material, sulfide, and a chlorinated disulfide.Som e other ethers (e.g. anisole, 1,2- and 1,4-dimethoxybenzene, 5-chloro-1,3-dimethoxybenzene) are unreactive under these conditions.
- Bell, Kevin H.
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p. 1209 - 1221
(2007/10/02)
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- SUR LA REACTION ENTRE LE CHLORURE DE PYRIDINIUM ET LES NITROALCANES PRIMAIRES
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The lack of homogeneity in the dealkylation of phenol ethers by pyridinium halides had been overcome in a few cases by the use of solvents such as quinoline.The high dissolving power of nitrohydrocarbons led us to study their behaviour in the presence of pyridinium chloride and of 2-methoxynaphthalene 1, taken as the reference ether.On one hand, nitrobenzene is a good solvent which homogenizes the reaction mixture but slows down the reaction; on the other hand, it is not so with nitroalkanes which quickly interact.Thus, a mixture of 2-methoxynaphthalene 1, nitroethane and pyridinium chloride yields, after refluxing, 1-chloro-2-methoxynaphthalene 2, 1-acetylpyridinium chloride oxime 3, acetic acid, acetohydroxamic acid 5, acetonitrile, acetamide and ammonium chloride, in various proportions according to the relative amounts of reagents or the heating duration.The unusual chlorination of 1 can be carried out with primary nitro-alkanes other than nitroethane.Methyl phenol ethers other than 1 can be halogenated if they have a sufficiently electrophilic position.With this method, we were able to synthesize a few mono- or dichlorinated compounds starting from 1,6- or 1,7-dimethoxynaphthalenes and 5-methoxybenzofuran.The study of the experiments run with varying proportions of reactants or with overaddition of one or the other of the resulting products suggests a few mechanisms.Pyridinium bromide induces the same type of reaction, but with lower yields.
- Dauzonne, Daniel,Demerseman, Pierre,Royer, Rene
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p. 601 - 608
(2007/10/02)
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