- Proton-Induced Electro-Transfer Reaction from Triplet Methoxynaphthalenes to Benzophenone via Triplet Exciplex
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A laser flash photolysis study at 355 nm has been carried out on acetonitrile-water (4:1 v/v) mixtures of the methoxynaphthalene-benzophenone-H2SO4 system.It is found that the proton-assisted photoionization reaction of triplet 1- and 2-methoxynaphthalene (ROMe) produced by triplet sensitization of benzophenone (BP) effectively occurs to produce the corresponding methoxynaphthalene cation radical (ROMe(1+.)) and benzophenone ketyl radical (>C(.)OH).The triplet energy-transfer reaction from triplet benzophenone (3BP*) to ROMe takes place as the primary event to produce triplet methoxynaphthalene (3ROMe*).The 1:1 triplet exciplex 3(ROMe...>CO)* having a weak charge-transfer structure is readily formed between 3ROMe* and BP with the equilibrium constants K1 (10.1 M-1 for 1ROMe; 4.0 M-1 for 2ROMe at 290 K).In the presence of protons, the triplet protonated exciplex 3(ROMe...>C(1+)OH)* is also produced by protonation to 3(ROMe...>CO)*.Subsequently, the intraexciplex electron-transfer reaction in 3(ROMe...>C(1+)OH)* takes place effectively, resulting in the formation of ROMe(1+.) and >C(.)OH.The presence of protons in the ROMe-BP system assists the photoionization of ROMe with the much lower energy (triplet energy of ROMe) than its ionization potential.The reaction mechanism is discussed in detail.
- Yamaji, Minoru,Sekiguchi, Tetuhiro,Hoshino, Mikio,Shizuka, Haruo
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Read Online
- A Mild Heteroatom (O -, N -, and S -) Methylation Protocol Using Trimethyl Phosphate (TMP)-Ca(OH) 2Combination
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A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2combination has been developed, which proceeds in DMF, or water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates for this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmentally friendly nature of this protocol make it an attractive alternative to the conventional base-promoted heteroatom methylation procedures.
- Tang, Yu,Yu, Biao
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- Direct Hydrodecarboxylation of Aliphatic Carboxylic Acids: Metal- and Light-Free
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A mild and inexpensive method for direct hydrodecarboxylation of aliphatic carboxylic acids has been developed. The reaction does not require metals, light, or catalysts, rendering the protocol operationally simple, easy to scale, and more sustainable. Crucially, no additional H atom source is required in most cases, while a broad substrate scope and functional group tolerance are observed.
- Burns, David J.,Lee, Ai-Lan,McLean, Euan B.,Mooney, David T.
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supporting information
p. 686 - 691
(2022/01/28)
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- Preparation method of naphthalene ring C marked α .
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The invention discloses C labeled α - naphthalene acetic acid preparation method and belongs to the field of radioisotope C labeled compounds. C-labeled α - naphthylacetic acid preparation method, C radioisotope labeling is introduced on a naphthalene ring structure α -naphthol acid, C labeling site is in α-position. The method has the advantages that the reaction raw materials are easily available, the synthesis steps are high in yield, the total yield is more 60%, C marker isotopes are less in use amount, and waste is generated. The marker site α-position on the naphthalene ring is less likely to be metabolized compared to C-labeled branched acetic acid, and the synthesized C-labeled compound provides a better study of α -naphthoic acid in the environment.
- -
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Paragraph 0046-0048; 0056-0058; 0066-0068
(2021/10/05)
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- Methylation with Dimethyl Carbonate/Dimethyl Sulfide Mixtures: An Integrated Process without Addition of Acid/Base and Formation of Residual Salts
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Dimethyl sulfide, a major byproduct of the Kraft pulping process, was used as an inexpensive and sustainable catalyst/co-reagent (methyl donor) for various methylations with dimethyl carbonate (as both reagent and solvent), which afforded excellent yields of O-methylated phenols and benzoic acids, and mono-C-methylated arylacetonitriles. Furthermore, these products could be isolated using a remarkably straightforward workup and purification procedure, realized by dimethyl sulfide‘s neutral and distillable nature and the absence of residual salts. The likely mechanisms of these methylations were elucidated using experimental and theoretical methods, which revealed that the key step involves the generation of a highly reactive trimethylsulfonium methylcarbonate intermediate. The phenol methylation process represents a rare example of a Williamson-type reaction that occurs without the addition of a Br?nsted base.
- Chan, Bun,Lui, Matthew Y.,Lui, Yuen Wai
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- Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
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Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
- Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
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supporting information
p. 20391 - 20399
(2021/08/13)
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- A highly stable all-in-one photocatalyst for aryl etherification: The NiIIembedded covalent organic framework
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The efficient conversion of aryl bromides to the corresponding aryl alkyl ethers by dual nickel/photocatalysis has seen great progress, but difficulties of recycling the photosensitizer or nickel complexes cause problems of sustainability. Here, we report the design of a novel, highly stable vinyl bridge 2D covalent organic framework (COF) containing Ni, which combines the role of photosensitizer and reactive site. The as-prepared sp2c-COFdpy-Ni acts as an efficient heterogeneous photocatalyst for C-O cross coupling. The sp2c-COFdpy-Ni can be completely recovered and used repeatedly without loss of activity, overcoming the limitations of the prior methods. Preliminary studies reveal that strong interlayer electron transfer may facilitate the generation of the proposed intermediate sp2c-COFdpy-NiI in a bimolecular and self-sustained manner. This all-in-one heterogeneous photocatalyst exhibits good compatibility of substrates and tolerance of functional groups. The successful attempt to expand the 2D COFs with this new catalyst into photocatalytic organic transformation opens an avenue for photoredox/transition metal mediated coupling reactions.
- Chen, Hao,Dong, Wenbo,Hu, Jianxiang,Rao, Li,Wang, Pei,Wang, Shengyao,Xiang, Yonggang,Yang, Yi
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p. 5797 - 5805
(2021/08/23)
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- Design, synthesis, and anticancer evaluation of benzophenone derivatives bearing naphthalene moiety as novel tubulin polymerization inhibitors
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A series of benzophenone derivatives bearing naphthalene moiety were designed, synthesized, characterized by 1H NMR, 13C NMR, and HRMS and evaluated for their antiproliferative activity against human breast cancer cell line (MCF-7). Most of the tested derivatives showed good to moderate cytotoxicity against MCF-7 cell line. Among them, compound 4u (IC50 = 1.47 ± 0.14 μM) was found to be the most active compound, which is more active than the standard drug cisplatin (IC50 = 15.24 ± 1.27 μM). In vitro tubulin polymerization inhibition assay, EBI competition assay, cell cycle analysis, and cell apoptosis assay identified that compound 4u was a new tubulin polymerization inhibitor by targeting the colchicine binding site. Besides, molecular docking study showed that compound 4u has high binding affinities with the colchicine binding site of tubulin through hydrogen bond, cation-π, and hydrophobic interaction.
- Wang, Guangcheng,Liu, Wenjing,Tang, Juan,Ma, Xue,Gong, Zipeng,Huang, Yong,Li, Yongjun,Peng, Zhiyun
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- Menbutone intermediate synthesis method
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The invention discloses a menbutone intermediate synthesis method, which comprises: pouring 1-naphthol, tetrabutylammonium bromide and sodium carbonate into dimethyl carbonate, heating to achieve a refluxing state, carrying out a complete reaction, carrying out pressure reducing distillation to remove the excess dimethyl carbonate, cooling to a room temperature, adding water, adding an acid in a dropwise manner to adjust the pH value to 3-4, extracting with dichloromethane, and reducing the pressure to remove the solvent so as to obtain the menbutone intermediate 1-methoxy naphthalene. According to the present invention, the method has characteristics of simple operation, high yield, no toxicity and no harm, greatly reduces the harm to operators and the environment, and is suitable for enterprise production.
- -
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Paragraph 0009-0011
(2019/05/02)
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- Method for methylation reaction
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The invention relates to a method for a methylation reaction. The method is characterized in that a reaction substrate is reacted in an organic solvent in the presence of an alkali with methyl trifluoroacetate as a methylation reagent to obtain a corresponding methylated product. The method is a new methylation method, and has the advantages of cheapness, easiness in operation, mild reaction conditions, wide application range of the substrate, avoiding of dimethyl sulfate, iodomethane and other highly toxic methylation reagents, and obtaining of the methylated product with a high yield.
- -
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Paragraph 0013
(2019/01/21)
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- Corey-Chaykovsky Cyclopropanation of Nitronaphthalenes: Access to Benzonorcaradienes and Related Systems
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Nitronaphthalene derivatives react as Michael acceptors in the Corey-Chaykovsky reaction with alkyl phenyl selenones and alkyl diphenyl sulfonium salts. Mechanistic studies reveal that sterically demanding substituents at the carbanionic center favor formation of cyclopropanes and suppress competitive β-elimination to the alkylated products. The transformation, demonstrated also on heterocyclic nitroquinoline and nitroindazolines, is an example of transition metal-free dearomatization method.
- Antoniak, Damian,Barbasiewicz, Micha?
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supporting information
p. 9320 - 9325
(2019/11/19)
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- Gold(i)-catalyzed Nicholas reaction with aromatic molecules utilizing a bifunctional propargyl dicobalt hexacarbonyl complex
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A benchtop-stable reagent for the catalytic Nicholas reaction was developed. By combining a propargyl dicobalt hexacarbonyl cluster with an ortho-alkynylbenzoate unit and a fluorous tag, introduction of a propargyl hexacarbonyl complex on various aromatic compounds having acid- or base-sensitive functional groups becomes possible by using a gold(i) catalyst. In addition, the presence of a fluorous tag facilitates convenient separation of the target products from byproducts.
- Okamura, Toshitaka,Fujiki, Shogo,Iwabuchi, Yoshiharu,Kanoh, Naoki
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supporting information
p. 8522 - 8526
(2019/10/02)
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- Exploiting ancillary ligation to enable nickel-catalyzed c-o cross-couplings of aryl electrophiles with aliphatic alcohols
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The use of (L)Ni(o-tolyl)Cl precatalysts (L = PAd-DalPhos or CyPAd-DalPhos) enables the C(sp2)-O cross-coupling of primary, secondary, or tertiary aliphatic alcohols with (hetero)aryl electrophiles, including unprecedented examples of such nickel-catalyzed transformations employing (hetero)aryl chlorides, sulfonates, and pivalates. In addition to offering a competitive alternative to palladium catalysis, this work establishes the feasibility of utilizing ancillary ligation as a complementary means of promoting challenging nickel-catalyzed C(sp2)-O cross-couplings, without recourse to precious-metal photoredox catalytic methods.
- MacQueen, Preston M.,Tassone, Joseph P.,Diaz, Carlos,Stradiotto, Mark
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supporting information
p. 5023 - 5027
(2018/04/24)
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- From Anilines to Aryl Ethers: A Facile, Efficient, and Versatile Synthetic Method Employing Mild Conditions
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We have developed a simple and direct method for the synthesis of aryl ethers by reacting alcohols/phenols (ROH) with aryl ammonium salts (ArNMe3+), which are readily prepared from anilines (ArNR′2, R′=H or Me). This reaction proceeds smoothly and rapidly (within a few hours) at room temperature in the presence of a commercially available base, such as KOtBu or KHMDS, and has a broad substrate scope with respect to both ROH and ArNR′2. It is scalable and compatible with a wide range of functional groups.
- Wang, Dong-Yu,Yang, Ze-Kun,Wang, Chao,Zhang, Ao,Uchiyama, Masanobu
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supporting information
p. 3641 - 3645
(2018/03/13)
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- Efficient and selective hydrogenation of C-O bonds with a simple sodium formate catalyzed by nickel
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A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed. Various esters, i.e. aryl, alkenyl, benzyl pivalates, and even the aryl ethers, were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%. Reactive functional groups such as C-C double bonds, carbonyl, CN, MeS and halogen groups are tolerable. This reaction can be used for the modification of complex molecules and carried out at a large scale.
- Xi, Xiaoxiang,Chen, Tieqiao,Zhang, Ji-Shu,Han, Li-Biao
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p. 1521 - 1524
(2018/02/19)
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- Masked N-Heterocyclic Carbene-Catalyzed Alkylation of Phenols with Organic Carbonates
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An easily prepared masked N-heterocyclic carbene, 1,3-dimethylimidazolium-2-carboxylate (DMI-CO2), was investigated as a “green” and inexpensive organocatalyst for the alkylation of phenols. The process made use of various low-toxicity and renewable alkylating agents, such as dimethyl- and diethyl carbonate, in a focused microwave reactor. DMI-CO2 was found to be a very active catalyst and excellent yields of a range of aryl alkyl ethers were obtained under relatively benign conditions. The observed difference in the conversion behavior of phenol methylation, in the presence of either the carbene or 1,8-diazabicycloundec-7-ene (DBU) catalyst, was rationalized on the basis of mechanistic investigations. The primary mode of action for the N-heterocyclic carbene is nucleophilic catalysis. Activation of the dialkyl carbonate electrophile results in concomitant evolution of an organo-soluble alkoxide, which deprotonates the phenolic starting material. In contrast, DBU is initially protonated by the phenol and thus consumed. Subsequent regeneration and participation in nucleophilic catalysis only becomes significant after some phenolate alkylation occurs.
- Lui, Matthew Y.,Yuen, Alexander K. L.,Masters, Anthony F.,Maschmeyer, Thomas
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p. 2312 - 2316
(2016/10/24)
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- Nickel-Catalyzed Alkoxy–Alkyl Interconversion with Alkylborane Reagents through C?O Bond Activation of Aryl and Enol Ethers
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A nickel-catalyzed alkylation of polycyclic aromatic methyl ethers as well as methyl enol ethers with B-alkyl 9-BBN and trialkylborane reagents that involves the cleavage of stable C(sp2)?OMe bonds is described. The transformation has a wide substrate scope and good chemoselectivity profile while proceeding under mild reaction conditions; it provides a versatile way to form C(sp2)?C(sp3) bonds that does not suffer from β-hydride elimination. Furthermore, a selective and sequential alkylation process by cleavage of inert C?O bonds is presented to demonstrate the advantage of this method.
- Guo, Lin,Liu, Xiangqian,Baumann, Christoph,Rueping, Magnus
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supporting information
p. 15415 - 15419
(2016/12/03)
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- Selective O-methylation of phenols and benzyl alcohols in simple pyridinium based ionic liquids
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Synthesis of pyridinium based ionic liquids were reported and applied as catalyst for the selective O-methylation of phenols and benzyl alcohols. The reactions were carried out by using dimethylcarbonate (DMC) as the methylating agent. High selectivity, high yield and recyclability of the ionic liquids are important features of the reactions.
- Das, Pranab Jyoti,Das, Jupitara
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- Methylation of phenol and its derivatives with dimethyl carbonate in the presence of Mn2(CO)10, W(CO)6, and Co2(CO)8
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Aryl methyl ethers were synthesized by reactions of phenol, substituted phenols, and α- and β-naphthols with dimethyl carbonate in the presence of manganese, tungsten, and cobalt carbonyls. Optimal reactant and catalyst ratios and reaction conditions were found to ensure selective formation of aryl methyl ethers.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.
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p. 330 - 334
(2015/05/04)
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- Dimethyl sulfite a potential agent for methylation
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The synthesis of methylated ether compounds is an important challenge. A pathway for the synthesis of methyl ethers was investigated using dimethyl sulfite (DMSi). Methylation of 1-octanol was carried out in liquid phase upon different heterogeneous organic and inorganic catalysts at 130°C. Aluminium oxide gave the best result with high conversion and moderate selectivity for methyl 1-octyl ether. Reactions in gas phase at higher temperatures (200°C) were also performed. Methyl 1-octyl ether was obtained in a very high level of selectivity up to 98%. Primary and secondary ethers from unsymmetrical alkyl methyl sulfite were also performed by SO2 extrusion.
- Mouselmani, Rim,Da Silva, Eric,Lemaire, Marc
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p. 8905 - 8910
(2015/11/02)
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- Au(i)-catalyzed triple bond alkoxylation/dienolether aromaticity-driven cascade cyclization to naphthalenes
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A novel strategy for the synthesis of multisubstituted naphthalenes was developed via a Au(i)-catalyzed alkyne alkoxylation/dienolether aromaticity-driven cascade cyclization using 1,5-enyne substrates. The functional group toleration was examined by synthesizing a series of substrates and the mechanism was also studied based on intermediates isolated through deuterium labeling experiments. This journal is the Partner Organisations 2014.
- Liu, Yongxiang,Guo, Jia,Liu, Yang,Wang, Xiaoyu,Wang, Yanshi,Jia, Xinyu,Wei, Gaofei,Chen, Lizhu,Xiao, Jianyong,Cheng, Maosheng
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p. 6243 - 6245
(2014/06/09)
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- Palladium-catalyzed methoxylation of aromatic chlorides with borate salts
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Herein we disclose a simple palladiumcatalyzed transformation for the methoxylation of aromatic chlorides with tetramethoxyborate salts. The procedure provides a new and efficient synthetic tool for the introduction of a methoxy group into aromatic systems. In addition, the reaction can be achieved using a wide range of aromatic and heteroaromatic chlorides, the cheapest class of halides.
- Tolnai, Gergely L.,Petho, Bálint,Králl, Péter,Nováka, Zoltán
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supporting information
p. 125 - 129
(2014/03/21)
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- Antimony(V) chloride as an efficient reagent for deprotection of methyl ethers
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This paper proposes a new and efficient method for the deprotection of methyl ethers using antimony pentachloride at ambient temperature. The procedure described here is a facile and practical method for the removal of the methyl group from aryl and benzyl methyl ethers. High selectivity was observed for the removal of the methyl group from dimethoxyarenes. The notable advantages of this protocol are mild reaction conditions, high yields, and the facility of workup procedure. The mechanism of the ether cleavage is proposed to explain this new reaction. Georg Thieme Verlag Stuttgart New York.
- Saadati, Fariba,Meftah-Booshehri, Hamid
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p. 1702 - 1706
(2013/09/02)
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- Iron-catalyzed cross-coupling reactions of alkyl grignards with aryl sulfamates and tosylates
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The iron-catalyzed cross-coupling of aryl sulfamates and tosylates has been achieved with primary and secondary alkyl Grignards. This study of iron-catalyzed cross-coupling reactions also examines the isomerization and β-hydride elimination problems that are associated with the use of isopropyl nucleophiles. While a variety of iron sources were competent in the reaction, the use of FeF3·3H2O was critical to minimize nucleophile isomerization.
- Agrawal, Toolika,Cook, Silas P.
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supporting information
p. 96 - 99
(2013/03/28)
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- Nickel-catalyzed hydrogenolysis of unactivated carbon-cyano bonds
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Selective hydrogenolysis of C-CN bonds can allow chemists to take advantage of ortho-directing ability, α-C-H acidity and electron withdrawing ability of the cyano group for synthetic manipulations. We have discovered hydrogenolysis of aryl and aliphatic cyanides under just 1 bar of hydrogen by using a nickel catalyst. This protocol was applied in the aryl cyanide directed functionalization reaction and α-substitution of benzyl cyanides.
- Patra, Tuhin,Agasti, Soumitra,Modak, Atanu,Maiti, Debabrata
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supporting information
p. 8362 - 8364
(2013/09/23)
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- Nickel-catalyzed decyanation of inert carbon-cyano bonds
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Nickel catalyzed decyanation of aryl and aliphatic cyanides with hydrosilane as the hydride source has been developed. This method is easy to handle, scalable and can be carried out without a glove box. The method has been applied in the cyanide directed functionalization reaction and α-substitution of benzyl cyanide.
- Patra, Tuhin,Agasti, Soumitra,Akanksha,Maiti, Debabrata
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supporting information
p. 69 - 71
(2013/02/21)
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- Iridium-catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of syngas
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A new iridium-catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe=cyclooctene) and racemic 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (rac-BINAP) in a mesitylene solution saturated with water. A catalytic amount of lithium chloride was also added to improve the catalyst turnover. The reaction has been applied to a variety of primary alcohols and gives rise to products in good to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)-BINAP species. First, dehydrogenation of the primary alcohol to the corresponding aldehyde takes place, which is then followed by decarbonylation to the product with one less carbon atom.
- Olsen, Esben P. K.,Madsen, Robert
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p. 16023 - 16029
(2013/02/22)
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- A continuous base-catalyzed methylation of phenols with dimethyl carbonate
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We have found that the use of a conventional, heated, standard 316 stainless steel or steel-braided PTFE tube reactor is a good and easily scalable alternative to the use of continuous microwave-heated reactors. The heat-up is almost as fast as with microwave heating, and the reactors can easily be scaled towards large-scale production. The transfer of the reported microwave procedure to the continuous flow method went very smoothly, and we found that we could further optimize the reaction to a catalytic procedure where only 10 mol % of DBU is needed with only 3 equiv of DMC. The reaction can be run neat in cases where the starting material is soluble in DMC as phenol is, or with a small amount of DMF (2-3 vol). The reaction is efficient for different types of phenols, giving a clean reaction in high yields.
- Tilstam, Ulf
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experimental part
p. 1150 - 1153
(2012/08/27)
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- A continuous methylation of phenols and N, H -heteroaromatic compounds with dimethyl carbonate
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The methylation of phenolic substrates has been reevaluated using sulfolane as solvent instead of DMF. The change of solvent gave in all cases cleaner production of the anisole products in very good yields. The reaction requires 0.1 equiv of DBU, 2-3 equiv of DMC, and 2-5 vols of sulfolane depending on the substrate. At 220 C the reaction time is 10 min. Sulfolane is completely stable under the reaction conditions, excluding unwanted impurities from the solvent. The reaction could also be extended to NH-indole and NH-imidazole derivatives utilizing 0.1 equiv of DBU and 2-3 equiv of DMC in 2 vols of sulfolane. All NH-heteroaromatic compounds gave clean N-methylation.
- Tilstam, Ulf
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p. 1974 - 1978
(2013/02/25)
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- Cine substitution of arenes using the aryl carbamate as a removable directing group
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An efficient and controlled means to achieve a rare cine substitution of arenes is reported. The methodology relies on the strategic use of aryl O-carbamates as readily removable directing groups for arene functionalization. The removal of aryl carbamates is achieved by employing an air-stable Ni(II) precatalyst, along with an inexpensive reducing agent, to give synthetically useful yields across a range of substrates. The net cine substitution process offers a new strategy for analogue synthesis, which complements the well-established logic for achieving arene functionalization by ipso substitution.
- Mesganaw, Tehetena,Fine Nathel, Noah F.,Garg, Neil K.
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supporting information; experimental part
p. 2918 - 2921
(2012/07/28)
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- Trideuteriomethoxylation of aryl and heteroaryl halides
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Direct access to trideuteriomethoxylated aromatic and heteroaromatic compounds has been developed. Various aryl and heteroaryl halides underwent d3-methoxylation under mild reaction conditions by using a catalyst system composed of the commercially available monodentate phosphane ligand tBuXPhos and Pd(OAc)2. Inexpensive CD3OD served as an efficient trideuteriomethoxylating agent. The simple and straightforward synthesis of labeled methyl (hetero)aryl ethers via palladium-catalyzed C-O cross-coupling reaction of (hetero)aryl halides with CD3OD was developed. The tBuXPhos ligand is used for the first time in ether synthesis. Copyright
- Dash, Pragyanditi,Janni, Manojkumar,Peruncheralathan, S.
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supporting information
p. 4914 - 4917,4
(2012/12/12)
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- Trideuteriomethoxylation of aryl and heteroaryl halides
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Direct access to trideuteriomethoxylated aromatic and heteroaromatic compounds has been developed. Various aryl and heteroaryl halides underwent d3-methoxylation under mild reaction conditions by using a catalyst system composed of the commercially available monodentate phosphane ligand tBuXPhos and Pd(OAc)2. Inexpensive CD3OD served as an efficient trideuteriomethoxylating agent. The simple and straightforward synthesis of labeled methyl (hetero)aryl ethers via palladium-catalyzed C-O cross-coupling reaction of (hetero)aryl halides with CD3OD was developed. The tBuXPhos ligand is used for the first time in ether synthesis. Copyright
- Dash, Pragyanditi,Janni, Manojkumar,Peruncheralathan
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supporting information
p. 4914 - 4917
(2013/01/14)
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- A convenient and practical synthesis of anisoles and deuterated anisoles by palladium-catalyzed coupling reactions of aryl bromides and chlorides
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Synthesis of anisole: Aryl and heteroaryl halides undergo selective C-O cross-coupling reactions with methanol in the presence of a Pd(OAc) 2/L3 catalyst system. The corresponding ethers were obtained under mild conditions in good yields. The catalytic methodology was also used for the synthesis of labeled deuterated anisoles in good yields (see scheme). Copyright
- Gowrisankar, Saravanan,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 2498 - 2502
(2012/03/27)
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- Oxidative trifluoromethylation of arylboronates with shelf-stable potassium (trifluoromethyl)trimethoxyborate
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Introducing CF3: Arylboronic acid pinacol esters are converted into the corresponding benzotrifluorides with the easy-to-use one-component trifluoromethylating reagent potassium (trifluoromethyl)trimethoxyborate, mediated by copper acetate under an oxygen atmosphere (see scheme). Copyright
- Khan, Bilal A.,Buba, Annette E.,Goossen, Lukas J.
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supporting information; experimental part
p. 1577 - 1581
(2012/03/10)
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- Nickel catalyzed cross-coupling of aryl C-O based electrophiles with aryl neopentylglycolboronates
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The efficiency of mesylates, sulfamates, esters, carbonates, carbamates, and methyl ethers as C-O-based electrophiles attached to the 1- or 2-position of naphthalene and to activated and nonactivated phenyl substrates was compared for the first time in Ni-catalyzed cross-coupling with phenyl neopentylglycolboronates containing electron-rich and electron-deficient substituents in their para-position. These experiments were performed in the presence of four different Ni(II)- and Ni(0)-based catalysts. Ni(II)-based catalysts mediate the cross-coupling of most 2-naphthyl C-O electrophiles with both arylboronic acids and with neopentylglycolboronates when K 3PO4 is used as base. The same catalysts are not efficient when CsF is used as base. However, Ni(0)-based catalysts exhibit selective efficiency, and when reactive, their efficiency is higher than that of Ni(II)-based catalysts in the presence of both K3PO4 and CsF. These results provide both reaction conditions for the cross-coupling, and for the elaboration of orthogonal cross-coupling methodologies of various C-O based electrophiles with aryl neopentylglycolboronates. With the exception of mesylates and sulfamates the efficiency of all other 2-naphthyl C-O electrophiles was lower in cross-coupling with aryl neopentylglycolboronates than with arylboronic acids
- Leowanawat, Pawaret,Zhang, Na,Percec, Virgil
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experimental part
p. 1018 - 1025
(2012/03/22)
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- Ambient carboxylation on a supported reversible CO2 carrier: Ketone to β-keto ester
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A reversible CO2 carrier (RCC) has been developed to perform carboxylation of ketone to β-ketoester under ambient CO2 pressure and temperature. RCC has been synthesized by immobilizing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on methylhydrosiloxane support and reacting with CO2 with 100% degree of functionalisation. RCC is found to be recyclable and shows retention of activity in 5 recycles. CO2 absorption under ambient temperature and desorption at 120°C renders the material suitable for carrying out carboxylation reactions at 25°C with excellent yields. The yield of the reaction can reach up to 100% with TON 200 in 4 h. The extent of the reaction primarily depends upon enol content of the substrate. β-Ketoacid produced during the reaction can be isolated and converted to its corresponding methyl ester derivative by reacting with methyl iodide.
- Beckman, Eric J.,Munshi, Pradip
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experimental part
p. 376 - 383
(2011/04/17)
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- Hyperaromatic stabilization of arenium ions: A remarkable cis stereoselectivity of nucleophilic trapping of β-hydroxyarenium ions by water
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Cis- and trans-1,2-dihydrodiol isomers of benzene undergo acid-catalyzed dehydration to form phenol. In principle the isomeric substrates react through a common β-hydroxybenzenium (cyclohexadienyl) carbocation. Notwithstanding, the isomers show a large difference in reactivity, kcis/k trans = 4500. This difference is reduced to kcis/k trans = 440 and 50 for the 1,2-dihydrodiols of naphthalene and 9,10-dihydrodiols of phenanthrene, respectively, and to 6.9 for the dihydrodiols of the nonaromatic 7,8-double bond of acenaphthylene. Because the difference in stabilities of cis- and trans-dihydrodiols should be no more than 2-3-fold, these results imply a high cis stereoselectivity for nucleophilic trapping of a β-hydroxyarenium cation by water in the reverse of the carbocation-forming reaction. This is confirmed by studies of the 10-hydroxy-9-phenanthrenium ion generated from aqueous solvolyses of the trans-9,10-bromohydrin derivative of phenanthrene and the monotrichloroacetate ester of the phenanthrene cis-9,10-dihydrodiol. The cis stereoselectivity of forward and reverse reactions is explained by the formation (in the "forward" reaction) of different conformations of carbocation from cis- and trans-dihydrodiol reactants with respectively β-C-H and β-C-OH bonds in pseudoaxial positions with respect to the charge center of the carbocation optimal for hyperconjugation. Formation of different conformations is constrained by departure of the (protonated) OH leaving group from a pseudoaxial position. The difference in stability of the carbocations is suggested to stem (a) from the greater hyperconjugative ability of a C-H than a C-OH bond and (b) from enhanced conjugation arising from the stabilizing influence of an aromatic ring in the no-bond resonance structures representing the hyperconjugation (C 6H6OH+ ? C6H5OH H+). This is consistent with an earlier suggestion by Mulliken and a demonstration by Schleyer that the benzenium ion is subject to hyperconjugative aromatic stabilization. It is proposed that, in analogy with the terms homoconjugation and homoaromaticity, arenium ions should be considered as "hyperaromatic".
- Lawlor, David A.,Kudavalli, Jaya Satyanarayana,MacCormac, Aoife C.,Coyne, Dara A.,Boyd, Derek R.,More O'Ferrall, Rory A.
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supporting information; experimental part
p. 19718 - 19728
(2012/01/31)
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- Oxidative dimerization of 4-methoxynaphthylamines in the presence of semiconductors
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Three types of 4-methoxynaphthylamines 4a-c were oxidized by treatment with metal oxides under molecular oxygen (O2). 4-Methoxy-1-naphthylamine 4a and 4,6-dimethoxy-1-naphthylamine 4b, on treatment with TiO2 under O2, gave mainly 2-amino-1,4-naphthoquinone derivatives 5a and 5b, respectively whereas 4,8-dimethoxy-1-naphthylamine 4c afforded an unique carbazole 6c as the major product.
- Takeya, Tetsuya,Takahashi, Yosuke,Okamoto, Iwao,Tamura, Osamu
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experimental part
p. 1479 - 1488
(2010/10/20)
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- Molecular complexes of 1,3,5-trinitrobenzene with naphthalene and its derivatives
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The relation between spectral parameters of molecular complexes formed by 1,3,5-trinitrobenzene with naphthalene derivatives and ionization potentials of the donor molecule is discussed. The molecular complexes were divided into three groups: naphthalene, naphthalene-1-amine, and naphthalene-2-amine derivatives. This division was substantiated in terms of the existence of several intermolecular interactions between the components and steric structure of the complexes. Problems related to classification of molecular complexes are discussed.
- Pryalkin
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experimental part
p. 2359 - 2366
(2010/05/02)
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- Comparative studies by using spectroscopic tools on the charge transfer (CT) band of a novel synthesized short-chain dyad in isotropic media and in a gel (P123)
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In the present investigation the photophysics of the synthesized short-chain organic dyad, 1-(4-chloro-phenyl)-3-(4-methoxy-naphthalen-1-yl)-propenone (MNCA) has been studied both in isotropic media and gel (P123) environment by using steady state, time-resolved spectroscopic techniques and fluorescence anisotropy decay. From the NMR and time-resolved spectroscopic studies E-isomeric form (elongated nature) of the charge-transfer species of the dyad MNCA appears to be the only isomeric form in the ground state and this conformation retains even after photoexcitation whatever be the nature of the environment, the isotropic solution or micro-heterogeneous medium (gel phase of P123).
- Bardhan, Munmun,Misra, Tapas,Chowdhury, Joydeep,Ganguly, Tapan
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experimental part
p. 142 - 148
(2010/04/03)
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- Synthesis of novel structurally simplified estrogen analogues with electron-donating groups in ring A
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A library of 25 novel estrogen analogues were prepared in five to eight steps from mostly commercially available substituted anisoles via bromination, formylation, Corey-Fuchs reaction, elimination, and Sonogashira reaction. Georg Thieme Verlag Stuttgart.
- Tietze, Lutz F.,Vock, Carsten A.,Krimmelbein, Ilga K.,Nacke, Linda
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experimental part
p. 2040 - 2060
(2009/12/27)
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- Methylation of arenes via Ni-catalyzed aryl C-O/F activation
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Aryl C-O and C-F can be transformed into C-Me via Ni-catalyzed coupling with MeMgBr under mild conditions. The Royal Society of Chemistry.
- Guan, Bing-Tao,Xiang, Shi-Kai,Wu, Tao,Sun, Zuo-Peng,Wang, Bi-Qin,Zhao, Ke-Qing,Shi, Zhang-Jie
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p. 1437 - 1439
(2008/12/21)
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- Hydroxide ion as electron source for photochemical Birch-type reduction and photodehalogenation
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The photochemical Birch-type reduction of arenes and the photodehalogenation of haloarenes by a hydroxide ion that acted as an electron source occurred in 2-PrOH. The efficiency of these photoreactions was dependent on the nature of the substrate, the concentration of NaOH, and the solvent used. These photoreactions provide an environmentally friendly method for the reduction of aromatic rings and dehalogenation.
- Yoshimi, Yasuharu,Ishise, Akihiro,Oda, Hiromu,Moriguchi, Yousuke,Kanezaki, Hiroki,Nakaya, Yukari,Katsuno, Kayoko,Itou, Tatsuya,Inagaki, Sho,Morita, Toshio,Hatanaka, Minoru
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p. 3400 - 3404
(2008/09/21)
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- Naphthyl-substituted carbocations: From peri interaction to cyclization
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The peri interaction of 1-functionalized naphthalenes equipped with a triarylmethyl cation at the 8-position has been studied because of the reversibility of the ring-closing reaction, which was monitored closely by NMR spectroscopy in the case of the cyclic ammonium salt 5b. Carbocycle 4a and N-heterocycle 5b did not exhibit any tendency for ring cleavage under various conditions, whereas the naphtho-annulated furan 4c underwent reversible ring cleavage under strongly acidic conditions. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Dyker, Gerald,Hagel, Marcel,Henkel, Gerald,Koeckerling, Martin
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experimental part
p. 3095 - 3101
(2009/04/11)
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- Solvent-free Williamson synthesis: An efficient, simple, and convenient method for chemoselective etherification of phenols and bisphenols
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Etherification of phenols with dimethyl- and diethylsulfates and benzyl chloride was performed efficiently in the presence of a suitable solid base, NaHCO3 or K2CO3, under solvent-free conditions. The reaction proceeded rapidly at low temperature, and the corresponding ethers were obtained with high purity and excellent yield. Selective etherification of electron-poor phenols in the presence of electron-rich ones and also selective mono-etherification of bisphenols are the noteworthy advantages of this method. This method is environmentally friendly. Copyright Taylor & Francis Group, LLC.
- Massah, Ahmad R.,Mosharafian, Masumeh,Momeni, Ahamad R.,Aliyan, Hamid,Naghash, H. Javaherian,Adibnejad, Mohamad
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p. 1807 - 1815
(2008/02/02)
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- Photochemical generation and reactivity of naphthyl cations: cine substitution
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The photochemical solvolyses of naphthalen-1-yl(phenyl)-iodonium tetrafluoroborate and naphthalen-2-yl(phenyl)-iodonium tetrafluoroborate in methanol regiospecifically yield the naphthalen-1- and -2-yl ethers but afford scrambled 1- and 2-phenylnaphthalene Friedel-Crafts products. It is demonstrated that singlet naphthyl cations account for the formation of the naphthyl ethers, but that the cine substitution is most likely to be due to the intermediacy of triplet naphthyl cations. According to the experiments reported here, the singlet naphthyl cations are lower in energy than their triplet isomers. High-level MO calculations for the cations in methanol support this finding. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Slegt, Micha,Minne, Floor,Zuilhof, Han,Overkleeft, Hermen S.,Lodder, Gerrit
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p. 5353 - 5363
(2008/03/14)
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- Ortho effect in the Bergman cyclization: Interception of p-benzyne intermediate by intramolecular hydrogen abstraction
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Intramolecular hydrogen atom (H-atom) abstraction from the o-OCH 3 group effectively intercepts the p-benzyne intermediate in the Bergman cycloaromatization of 2,3-diethynyl-1-methoxybenzene (1) before this intermediate undergoes either retro-Bergman ring opening or external H-atom abstraction. This process leads to the formation of a new diradical and renders the cyclization step essentially irreversible. Chemical and kinetic consequences of this phenomenon were investigated through the combination of computational and experimental studies.
- Zeidan, Tarek A.,Manoharan, Mariappan,Alabugin, Igor V.
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p. 954 - 961
(2007/10/03)
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- Solid state S-methylation of thiols and O-methylation of phenols and naphthols with dimethyl sulfate under microwave irradiation
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Mild and efficient S-methylation of thiols and o-methylation of phenols and naphthals occurs with dimethyl sulfate (DMS) supported on basic alumina under microwave irradiation in solventless system. Copyright Taylor & Francis Inc.
- Heravi, Majid M.,Ahari, Neda Zamani,Oskooie, Hossein A.,Ghassemzadeh, Mitra
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p. 1701 - 1712
(2007/10/03)
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- Microwave-assisted methylation of carboxylic acids and phenolic compounds with dimethyl-carbonate under solvent-free condition
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Phenolic compounds and carboxylic acids are methylated with dimethyl carbonate in the presence of a catalytic amount of BF3· OEt2, DBU, or KOH, in good to excellent yields under microwave irradiation and solvent-free conditions.
- Rajabi, Fatemeh,Saidi, Mohammad R.
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p. 4179 - 4188
(2007/10/03)
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- One-pot synthesis of 4-alkoxybenzo[c]thiophenes
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The reaction of N-bromosuccinimide with 4,5,6,7-tetrahydrobenzo[c]thiophen-4-ones in the presence of 2,2′-azo-bis-isobutyronitrile followed by heating under reflux with different alcohols produces 4-alkoxybenzo[c]thiophenes in good yield.
- Akbarzadeh, Tahmineh,Shafiee, Abbas
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p. 1455 - 1462
(2007/10/03)
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- Accelerated process for preparing O-methyl phenols, N-methyl heteroaromatic compounds, and methylated aminophenols
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An accelerated process for preparing an O-methyl phenol comprising reacting a phenol with dimethyl carbonate in the presence of a catalyst selected from 1,8-diazabicyclo[5.4.0]undec-7-ene; 1,4-diazabicyclo[2.2.2]octane; and dimethylaminopyridine. According to another aspect, the invention provides an accelerated process for preparing an N-methyl heteroaromatic compound comprising reacting an NH-containing heteroaromatic compound with dimethyl carbonate in the presence of a catalyst selected from 1,8-diazabicyclo[5.4.0]undec-7-ene; 1,4-diazabicyclo[2.2.2]octane; and dimethylaminopyridine. According to an additional aspect, the invention provides an accelerated process for preparing a methylated aminophenol comprising reacting an aminophenol having at least one N—H with dimethyl carbonate in the presence of a catalyst selected from 1,8-diazabicyclo[5.4.0]undec-7-ene; 1,4-diazabicyclo[2.2.2]octane; and dimethylaminopyridine. The process of the invention is especially advantageous since the process: (1) utilizes an environmentally friendly methylating reagent, dimethylcarbonate; (2) produces a high yield of the O-methyl phenols, N-methyl aromatic amines, and/or methylated aminophenols, generally 97-100% conversion; and (3) does not require a high-pressure (autoclave) reactor.
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