- Radical Decarboxylative Carbometalation of Benzoic Acids: A Solution to Aromatic Decarboxylative Fluorination
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Abundant aromatic carboxylic acids exist in great structural diversity from nature and synthesis. To date, the synthetically valuable decarboxylative functionalization of benzoic acids is realized mainly by transition-metal-catalyzed decarboxylative cross couplings. However, the high activation barrier for thermal decarboxylative carbometalation that often requires 140 °C reaction temperature limits both the substrate scope as well as the scope of suitable reactions that can sustain such conditions. Numerous reactions, for example, decarboxylative fluorination that is well developed for aliphatic carboxylic acids, are out of reach for the aromatic counterparts with current reaction chemistry. Here, we report a conceptually different approach through a low-barrier photoinduced ligand to metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation strategy, which generates a putative high-valent arylcopper(III) complex, from which versatile facile reductive eliminations can occur. We demonstrate the suitability of our new approach to address previously unrealized general decarboxylative fluorination of benzoic acids.
- Xu, Peng,López-Rojas, Priscila,Ritter, Tobias
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supporting information
p. 5349 - 5354
(2021/05/05)
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- Mechanically induced solvent-free esterification method at room temperature
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Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of grinding. In addition, the I2/KH2PO2 protocol was successfully extended to the late-stage diversification of natural products showing the robustness of this useful approach. Further application of this method in the synthesis of inositol nicotinate was also discussed. This journal is
- Zheng, Lei,Sun, Chen,Xu, Wenhao,Dushkin, Alexandr V.,Polyakov, Nikolay,Su, Weike,Yu, Jingbo
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p. 5080 - 5085
(2021/02/05)
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- Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
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The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
- Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
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- Ligand-Controlled C?O Bond Coupling of Carboxylic Acids and Aryl Iodides: Experimental and Computational Insights
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Palladium-catalyzed cross-coupling reactions between carboxylic acids and aryl halides have several possible competitive pathways. Decarboxylative C?C bond coupling and C?H arylation are well established in the literature. However, direct C?O bond coupling between carboxylic acids and aryl halides has received little success. In this report, we describe a protocol for exclusive C?O bond formation, enabled by a bidentate N,N-ligand such as 1,10-phenanthroline. The reaction is general for a broad range of carboxylic acids and iodoarenes. Experimental evidence and computational results suggest a high energy barrier for the alternative pathway of decarboxylative carbon-carbon bond coupling. (Figure presented.).
- Li, Li,Song, Feifei,Zhong, Xiumei,Wu, Yun-Dong,Zhang, Xinhao,Chen, Jiean,Huang, Yong
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supporting information
p. 126 - 132
(2019/11/28)
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- Palladium-catalyzed aryloxy- and alkoxycarbonylation of aromatic iodides in γ-valerolactone as bio-based solvent
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Fossil-based solvents and triethylamine as a toxic and volatile base were successfully replaced with γ-valerolactone as a non-volatile solvent and K2CO3 as inorganic base in the alkoxy- and aryloxycarbonylation of aryl iodides using phosphine-free Pd catalyst systems. By this, the traditional systems were not simply replaced but also significantly improved. In the study, the effects of different reaction parameters, i.e. the use of several other solvents, the temperature, the carbon monoxide pressure, the base and the catalyst concentrations, were evaluated in details on the efficiency of the carbonylations. To gather some information on the mechanism of these reactions, the effects of the electronic parameters (σ) of various aromatic substituents of the aryl iodides as well as the influence of para-substitution of phenol were investigated on the activity. For a comparison, the aryl-substituted aryl iodides were also reacted with methanol and aryl iodide was also alkoxycarbonylated using several different lower alcohols. From the observed correlations between the electronic parameters of the aromatic substituents and the rates, it appears that the rate determining step is the oxidative addition of Ar–I to Pd0, provided that sufficient amounts of nucleophiles are present for the ester formation. If this is not the case, the rate of nucleophile attack might determine the overall rate.
- Tukacs, József M.,Marton, Bálint,Albert, Eszter,Tóth, Imre,Mika, László T.
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- Nickel-Catalyzed Cross-Coupling of Aryl Redoxactive Esters with Aryl Zinc Reagents
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A nickel-catalyzed aryl-aroyloxyl C(sp2)-O radical cross-coupling reaction conducted using a redox active ester with aryl zinc reagent was developed. This method demonstrates a new disconnection approach for formation of aryl aryl esters. In the one-pot sequential process, the readily available aryl carboxylic acids can be converted into functionalized aryl aryl esters and heteroaryl esters. This protocol is amenable to the gram-scale synthesis. The present method has a wide substrate scope and high functional group tolerance.
- Shih, Bo-Hao,Basha, R. Sidick,Lee, Chin Fa
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p. 8862 - 8866
(2019/09/30)
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- Palladium-Catalyzed Aerobic Oxidative Coupling of Amides with Arylboronic Acids by Cooperative Catalysis
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The first fluoride and palladium co-catalyzed conversion of amide to ester through an aerobic oxidative coupling pathway is reported. This new approach presents a practical process that employs easily available oxygen and commercially available arylboronic acids as coupling partners, uses a wide range of N- tosylamides, and proceeds under mild reaction conditions. This protocol demonstrates broad functional group tolerance, and provides an alternative option to synthesize esters from N-tosylamides which obtained by simply N-functionalization of secondary amides.
- Li, Yue,Wu, Hongxiang,Zeng, Zhuo
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supporting information
p. 4357 - 4361
(2019/07/09)
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- Enol Ester Intermediate Induced Metal-Free Oxidative Coupling of Carboxylic Acids and Arylboronic Acids
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A facile, efficient and environmentally friendly methodology for the preparation of phenolic esters is realized via metal-free coupling of carboxylic acids and arylboronic acids. This sequential one pot reaction, employing methyl propiolate as an activating reagent, proceeds through the formation of enol ester intermediate, followed by a nucleophilic attack on the C-O bond under the oxidation of hydrogen peroxide. These studies display that enol esters, despite previously being overlooked as synthetic intermediates, would be the valuable building blocks for developing carbon–carbon and carbon–heteroatom bond-forming reactions.
- Xu, Xianjun,Feng, Huangdi,Li, Huiqiong,Huang, Liliang
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p. 3921 - 3928
(2019/06/24)
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- Rhodium-catalysed aryloxycarbonylation of iodo-aromatics by 4-substituted phenols with carbon monoxide or paraformaldehyde
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Rhodium-catalysed phenoxycarbonylation of aryl iodides were carried out under carbon-monoxide atmosphere and in the absence of CO, using paraformaldehyde as an alternative surrogate for carbonylation reactions. Both strategies proved to be efficient for the synthesis of the corresponding phenyl esters. High pressure reactions provided the ester products with good selectivity, however lower activity was achieved compared to palladium containing systems. Using paraformaldehyde as carbon-monoxide source special reaction conditions are required, thus dramatic changes observed during optimisation reactions. Using in situ generated Rh-diphosphine catalyst systems, remarkable influence of ligand structure and solvent composition was observed on the activity and chemoselectivity. The substrate scope and the substituent effect were also investigated.
- Seni, Anas Abu,Kollár, László,Mika, László T.,Pongrácz, Péter
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- Preparation method for synthesis of phenolic ester through thiocarboxylic acid mediated visible light catalyzed phenol acylation reaction
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The invention discloses a preparation method for synthesis of phenolic ester through a thiocarboxylic acid mediated visible light catalyzed phenol acylation reaction. Thiocarboxylic acid compounds andphenol compounds are subjected to a site specific reaction under certain conditions to produce phenolic ester compounds, wherein the certain conditions are as follows: under the conditions of normaltemperature, normal pressure and visible light, K2CO3 is used as an alkaline catalyst, terpyridyl ruthenium dichloride hexahydrate is used as a photosensitizer and acetonitrile is used as a reaction solvent. Synthesis of phenolic ester under catalysis of visible light is realized, thiocarboxylic acid is used as an acylation reagent, and the site specific phenol esterification reaction is realizedefficiently under mild conditions of normal temperature, normal pressure and visible light. The method has mild reaction conditions, large substrate functional group tolerance, high applicability andhigh yield, and an efficient, reliable and economical preparation method is provided for synthesis of phenolic ester.
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Paragraph 0017; 0018; 0074; 0075; 0076
(2018/07/30)
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- Palladium-Catalyzed Oxidative Carbonylation of Aryl Hydrazines with CO and O2 at Atmospheric Pressure
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Palladium-catalyzed aerobic oxidative aminocarbonylation and alkoxycarbonylation reactions with aryl hydrazines as coupling partners have been developed. The oxidative carbonylation of aryl hydrazines proceeded smoothly at atmospheric pressure CO, employi
- Tu, Yongliang,Yuan, Lin,Wang, Tao,Wang, Changliu,Ke, Jiamei,Zhao, Junfeng
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p. 4970 - 4976
(2017/05/12)
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- Diacyl Disulfide: A Reagent for Chemoselective Acylation of Phenols Enabled by 4-(N,N-Dimethylamino)pyridine Catalysis
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A general and excellent acylation reagent, diacyl disulfide, was uncovered for efficient ester formation enabled by DMAP (4-(N,N-dimethylamino)pyridine) catalysis. This protocol offered a promising synthetic platform on site-selective acylation of phenolic and primary aliphatic hydroxyl groups, which greatly expanded the realm of protecting group chemistry. The importance of the reagent was also reflected by its excellent moisture tolerance, high efficiency, and potential in synthetic chemistry and biologically meaningful natural product modification.
- Liu, Hong-Xin,Dang, Ya-Qian,Yuan, Yun-Fei,Xu, Zhi-Fang,Qiu, Sheng-Xiang,Tan, Hai-Bo
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supporting information
p. 5584 - 5587
(2016/11/17)
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- Copper-Mediated Functionalization of Aryl Trifluoroborates
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This paper describes the Cu(OTf)2-mediated coupling of aryl and heteroaryl trifluoroborates with tetrabutylammonium or alkali metal salts to form C-O, C-N, and C-halogen bonds. The reactions proceed under mild conditions (often room temperature over 16 hours) with carboxylate, halide, and azide salts, all nucleophiles that have been underrepresented in the copper cross-coupling literature. Preliminary results show that copper salts bearing weakly coordinating X-type ligands are essential for enabling these transformations to proceed under mild conditions.
- Schimler, Sydonie D.,Sanford, Melanie S.
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supporting information
p. 2279 - 2284
(2016/10/06)
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- Ligand-free palladium-catalyzed aerobic oxidative coupling of carboxylic anhydrides with arylboronic acids
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We report a new, effective and environmentally friendly protocol for selective aerobic oxidative coupling of arylboronic acids with carboxylic anhydrides in the presence of ligand-free palladium catalyst. The aryl benzoates are obtained in good to excellent yields.
- Yin, Weiyan,He, Haifeng,Zhang, Yani,Long, Tong
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p. 2402 - 2406
(2014/10/15)
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- Trichlorophenyl formate: Highly reactive and easily accessible crystalline CO surrogate for palladium-catalyzed carbonylation of aryl/alkenyl halides and triflates
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The high utility of 2,4,6-trichlorophenyl formate, a highly reactive and easily accessible crystalline CO surrogate, is demonstrated. The decarbonylation with NEt3 to generate CO proceeded rapidly at rt, thereby allowing external-CO-free Pd-catalyzed carbonylation of aryl/alkenyl halides and triflates. The high reactivity of the CO surrogate enabled carbonylation at rt and significantly reduced the quantities of formate to near-stoichiometric levels. The obtained trichlorophenyl esters can be readily converted to a variety of carboxylic acid derivatives in high yields.
- Ueda, Tsuyoshi,Konishi, Hideyuki,Manabe, Kei
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supporting information
p. 5370 - 5373,4
(2012/12/12)
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- Palladium-catalyzed aerobic oxidative coupling of acyl chlorides with arylboronic acids
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The first example of a palladium-catalyzed aerobic oxidative coupling of acyl chlorides with arylboronic acids has been developed, leading to a wide range of aryl benzoates in good to excellent yields. This catalytic system shows broad functional group tolerance. Preliminary mechanistic experiments using deuterium labeling showed that the oxygen atom was derived from dioxygen. Copyright
- Chen, Jiuxi,Peng, Yong,Liu, Miaochang,Ding, Jinchang,Su, Weike,Wu, Huayue
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supporting information
p. 2117 - 2122
(2012/11/07)
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- Ruthenium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols
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An efficient methodology to access benzoate derivatives via tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols catalyzed by ruthenium/NHC was developed. This operationally simple one-pot process uses O2 as the clean oxidant, producing esters in good to excellent yields.
- Zhang, Di,Pan, Changduo
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experimental part
p. 41 - 45
(2012/06/18)
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- NHC/Iron cooperative catalysis: Aerobic oxidative esterification of aldehydes with phenols
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An NHC/iron cooperative catalytic system mediates the aerobic oxidative esterification of aldehydes with phenols. The use of equimolar amounts of reactants led to good to excellent isolated yields of esters.
- Reddy, R. Sudarshan,Rosa, Joao N.,Veiros, Luis F.,Caddick, Stephen,Gois, Pedro M. P.
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supporting information; experimental part
p. 3126 - 3129
(2011/05/12)
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- Palladium/NHC-catalyzed oxidative esterification of aldehydes with phenols
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A palladium-catalyzed oxidative esterification of aldehydes with phenols is described, using air as the clean oxidant. This reaction tolerates many functional groups, providing esters with yields ranging from moderate to excellent.
- Zhang, Manli,Zhang, Shouhui,Zhang, Guoying,Chen, Fan,Cheng, Jiang
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experimental part
p. 2480 - 2483
(2011/05/16)
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- Radical OfC transposition: A metal-free process for conversion of phenols into benzoates and benzamides
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We report a metal-free procedure for transformation of phenols into esters and amides of benzoic acids via a new radical cascade. Diaryl thiocarbonates and thiocarbamates, available in a single high-yielding step from phenols, selectively add silyl radicals at the sulfur atom of the CdS moiety. This addition step, analogous to the first step of the Barton-McCombie reaction, produces a carbon radical which undergoes 1,2 OfC transposition through an O-neophyl rearrangement. The usually unfavorable equilibrium in the reversible rearrangement step is shifted forward via a highly exothermic C-S bond scission in the O-centered radical, which furnishes the final benzoic ester or benzamide product. The metal-free preparation of benzoic acid derivatives from phenols provides a potentially useful alternative to metal-catalyzed carbonylation of aryl triflates.
- Baroudi, Abdulkader,Alicea, Jeremiah,Flack, Phillip,Kirincich, Jason,Alabugin, Igor V.
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experimental part
p. 1521 - 1537
(2011/06/11)
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- DIRECT CONVERSION OF PHENOLS INTO AMIDES AND ESTERS OF BENZOIC ACID
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A method is provided for the preparation of an aromatic carboxylic acid aryl ester or an N-aryl aromatic carboxamide. The method comprises contacting an O,O-diaryl thiocarbonate or an O-aryl-N-aryl thiocarbamate with a reactant that regioselectively reacts with sulfur, which contact causes an O-neophyl rearrangement, thereby forming either the aromatic carboxylic acid aryl ester or the N-aryl aromatic carboxamide, respectively.
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Page/Page column 16, 18
(2011/10/12)
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- Palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols
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A palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols to access aryl benzoate derivatives is described. The procedure tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, fluoro and bromo groups. Thus, it represents a practically alternative method to access aryl benzoate derivatives.
- Luo, Fang,Pan, Changduo,Cheng, Jiang,Chen, Fan
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supporting information; experimental part
p. 5878 - 5882
(2011/09/12)
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- Silver-mediated fluorination of aryl silanes
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A regiospecific silver-mediated fluorination of aryl silanes is reported. The reaction is operationally simple, and employs Ag2O as readily available, inexpensive silver source, which can be recovered.
- Tang, Pingping,Ritter, Tobias
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p. 4449 - 4454
(2011/08/03)
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- Radical 1,2-o→c transposition for conversion of phenols into benzoates by o-neophyl rearrangement/fragmentation cascade
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Figure Presented Radical merry-go-round! Diaryl thiocarbonates, available in a single step from phenols, can be directly transformed into benzoates by a new radical cascade that transposes O and C atoms at the aromatic core. The cascade bypasses the common Barton McCombie fragmentation in favor of the usually unfavorable O-neophyl rearrangement, which is rendered irreversible and efficient by a highly exothermic C-S bond scission in the O-centered radical (see scheme; FG = functional group).
- Baroudi, Abdulkader,Alicea, Jeremiah,Alabugin, Igor Y.
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supporting information; experimental part
p. 7683 - 7687
(2010/08/22)
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- NHC-iron-catalyzed aerobic oxidative aromatic esterification of aldehydes using boronic acids
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(Figure presented) NHC-iron complexes prepared in situ very efficiently afforded benzoates via the aerobic oxidative aromatic esterification of aldehydes with boronic acids. This method uses equimolar amounts of both the aldehyde and the boronic acid allo
- Rosa, Joao N.,Reddy, R. Sudarshan,Candeias, Nuno R.,Cal, Pedro M. S. D.,Gois, Pedro M. P.
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supporting information; experimental part
p. 2686 - 2689
(2010/09/03)
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- FLUORINATION OF ORGANIC COMPOUNDS
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Methods for fluorinating organic compounds are described herein.
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Page/Page column 107
(2010/07/10)
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- Method for acylation or sulphonylation of an aromatic compound
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The present invention relates to a process for the acylation or sulphonylation of an aromatic compound. More particularly, the invention relates to a process for the acylation or sulphonylation of an activated or deactivated aromatic compound. The invention is applied to the preparation of aromatic ketones or sulphones. The process for the acylation or sulphonylation of an aromatic compound which consists in reacting at least one aromatic compound with an acylating or sulphonylating agent, in the presence of a Friedel-Crafts catalyst is characterized in that the acylation or sulphonylation reaction is carried out in liquid phase under microwave irradiation.
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Page column 21
(2008/06/13)
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- Ester derivatives
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An ester derivative represented by the following formula (I). STR1 In the formula, V, W, X, Y and Z represent a hydrogen atom or a halogen atom, respectively. The present invention also comprises a liquid crystal composition containing the ester derivativ
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- Preparation of 4-fluorophenol and 4-fluorobenzoic acid by the Baeyer-Villiger reaction
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The possibility of preparing 4-fluorophenol or 4-fluorobenzoic acid via the Baeyer-Villiger reaction starting from unsymmetrical fluoroaryl ketones is disscussed.Several unsymmetrical 4-fluorobenzophenones having different substituents in the fluorine-free aryl group were prepared and converted to esters by treatment with peracetic acid.The electrophilicity of the substituents influenced the molecular structure of the ester formed as a result of a carbon-to-oxygen migration, and hence 4-fluorophenol or 4-fluorobenzoic acid formation.Electron-withdrawing substituents favoured the formation of 4-fluorophenol in good yields, while electron-donating substituents formed 4-fluorobenzoic acid preferentially.
- Conte, L.,Napoli, M.,Gambaretto, J. P.,Guerrato, A.,Carlini, F. M.
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- Homolytic Reactions of Polyfluoroaromatic Compounds. Part 16. Competitive Phenylation of Polyfluorobenzenes
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Pairs of polyfluorobenzenes were allowed to compete for phenyl radicals generated by thermolysis of benzoyl peroxide at 80 deg C.From the relative yields of biaryl, and the yields of each biaryl formed upon arylation of each arene individually, the relative rates of attack of each site in each arene were deduced.Neither iron(III) benzoate nor trichloroacetic acid uniformly improved yields of biaryl, although in some cases the isomer distribution altered, when decomposition of benzoyl peroxide was carried out in the presence of such additives, to favour products of aryldehydrogenation or of aryldefluorination, respectively.Competition did not usually affect the distribution of attack of a particular arene, except when hexafluorobenzene was used, in which case greater selectivity of attack of the second arene occured.This suggested the formation of a 'stabilised' phenyl radical, and supported an earlier suggestion of species such as >; other evidence also supported the postulate.
- Allen, Kim J.,Bolton, Roger,Williams, Gareth H.
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p. 691 - 696
(2007/10/02)
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