- Chemoselective and Site-Selective Reductions Catalyzed by a Supramolecular Host and a Pyridine-Borane Cofactor
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Supramolecular catalysts emulate the mechanism of enzymes to achieve large rate accelerations and precise selectivity under mild and aqueous conditions. While significant strides have been made in the supramolecular host-promoted synthesis of small molecules, applications of this reactivity to chemoselective and site-selective modification of complex biomolecules remain virtually unexplored. We report here a supramolecular system where coencapsulation of pyridine-borane with a variety of molecules including enones, ketones, aldehydes, oximes, hydrazones, and imines effects efficient reductions under basic aqueous conditions. Upon subjecting unprotected lysine to the host-mediated reductive amination conditions, we observed excellent ?-selectivity, indicating that differential guest binding within the same molecule is possible without sacrificing reactivity. Inspired by the post-translational modification of complex biomolecules by enzymatic systems, we then applied this supramolecular reaction to the site-selective labeling of a single lysine residue in an 11-amino acid peptide chain and human insulin.
- Morimoto, Mariko,Cao, Wendy,Bergman, Robert G.,Raymond, Kenneth N.,Toste, F. Dean
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supporting information
p. 2108 - 2114
(2021/02/06)
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- Mono- and Di-Mesoionic Carbene-Boranes: Synthesis, Structures and Utility as Reducing Agents
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Mesoionic carbenes (MIC) of the 1,2,3-triazol-5-ylidene type are currently popular ligands in organometallic chemistry. Their use in main group chemistry has been rather limited. In this contribution we present mono- and di-MIC-boranes with MICs based on triazolylidenes. The synthesis involves in-situ deprotonation of the corresponding triazolium salts and their reaction with boranes to form the desired compounds. Whereas this reaction route worked well for all triazolium salts derived from the 1,4-regioisomer of the triazoles, for the methlyene-bridged bi-triazolium salt derived from a 1,5-substiuted triazole, we observed the unexpected decomposition of the bi-triazolium and the formation of a triazole-borane with a new N?B bond. All compounds were characterized via multinuclear NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction. Furthermore, the MIC-boranes were used as reducing agents for the reduction of the C=O of aldehydes to the corresponding alcohols.
- Stein, Felix,Kirsch, Marius,Beerhues, Julia,Albold, Uta,Sarkar, Biprajit
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supporting information
p. 2417 - 2424
(2021/06/17)
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- Copper(II)-Catalyzed Selective Hydroboration of Ketones and Aldehydes
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A novel nonanuclear copper(II) complex obtained by a facile one-pot self-assembly was found to catalyze the hydroboration of ketones and aldehydes with the absence of an activator under mild, solvent-free conditions. The catalyst is air- and moisture-stable, displaying high efficiency (1980 h-1 turnover frequency, TOF) and chemoselectivity on aldehydes over ketones and ketones over imines. This represents a rare example of divalent copper catalyst for the hydroboration of carbonyls.
- Zeng, Haisu,Wu, Jing,Li, Sihan,Hui, Christina,Ta, Anita,Cheng, Shu-Yuan,Zheng, Shengping,Zhang, Guoqi
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supporting information
p. 401 - 406
(2019/01/23)
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- Method for preparing polyfluorobenzyl alcohol
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The invention relates to a method for preparing polyfluorobenzyl alcohol, and belongs to the technical field of organic synthesis. The method comprises the following steps: 1. allowing polyfluorobenzoic acid and a dehydrating reagent to a reflux reaction; 2 adding sodium borohydride to a product obtained in step 1 to perform a reduction reaction to obtain the polyfluorobenzyl alcohol. Although themethod provided by the invention requires two steps, the selectivity of the two-step reaction is high, no side reaction exists, no organic three wastes exist, and the yield is also higher than that of the existing method.
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Paragraph 0039; 0040
(2018/05/16)
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- Cooperative interplay between a flexible PNN-Ru(II) complex and a NaBH4 additive in the efficient catalytic hydrogenation of esters
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A catalyst loading of between 0.001-0.05 mol% of the PNN-bearing ruthenium(II) complex [fac-PNN]RuH(PPh3)(CO) (PNN = 8-(2-diphenylphosphinoethyl)amidotrihydroquinoline), in combination with 5 mol% NaBH4, efficiently catalyzes the hydrogenation of esters to their corresponding alcohols under mild pressures of hydrogen. Both aromatic and aliphatic esters can be converted with high values of TON or TOF achievable. Mechanistic investigations using both DFT calculations and labeling experiments highlight the cooperative role of NaBH4 in the catalysis while the catalytically active species has been established as trans-dihydride [mer-PNHN]RuH2(CO) (PNHN = 8-(2-diphenylphosphinoethyl)aminotrihydroquinoline). The stereo-structure of the PNHN-ruthenium species greatly affects the activity of the catalyst, and indeed the cis-dihydride isomer [fac-PNHN]RuH2(CO) is unable to catalyze the hydrogenation of esters until ligand reorganization occurs to give the trans isomer.
- Wang, Zheng,Chen, Xiangyang,Liu, Bo,Liu, Qing-Bin,Solan, Gregory A.,Yang, Xinzheng,Sun, Wen-Hua
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p. 1297 - 1304
(2017/05/05)
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- Half-sandwich ruthenium(II) complexes with water-soluble Schiff base ligands: Synthesis and catalytic activity in transfer hydrogenation of carbonyl compounds
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New ionic Schiff-base ligands have been synthesized by condensation of (3-formyl-4-hydroxybenzyl)triphenylphosphonium and 3-(3-formyl-4-hydroxybenzyl)-1-methyl-1H-imidazol-3-ium chloride and hexafluorophosphate salts with N,N-dimethylethylenediamine. Treatment of the dimeric derivative [{RuCl(μ-Cl)(η6-p-cymene)}2] with two equivalents of these ligands allowed the preparation of novel mononuclear water-soluble Ru(II) complexes, which proved to be catalytically active in the transfer hydrogenation of ketones and aldehydes under aqueous conditions.
- Azizi Talouki, Somayeh,Grivani, Gholamhossein,Crochet, Pascale,Cadierno, Victorio
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p. 142 - 148
(2016/12/23)
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- Aluminum Monohydride Catalyzed Selective Hydroboration of Carbonyl Compounds
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The well-defined aluminum monohydride compound [{(2,4,6-Me3-C6H2)NC(Me)}2(Me)(H)]AlH·(NMe2Et) (1) catalyzes hydroboration of a wide range of aldehydes and ketones under mild reaction conditions. Moreover, compound 1 displayed chemoselective hydroboration of aldehydes over ketones at rt.
- Jakhar, Vineet Kumar,Barman, Milan Kr.,Nembenna, Sharanappa
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supporting information
p. 4710 - 4713
(2016/09/28)
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- Dinickel complexes with anthyridine-based ligands
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Two new dinickel complexes with anthyridine-based ligands, 5-phenyl-2,8-bis(2-pyridinyl)-1,9,10-anthyridine (L2) and 5-phenyl-2,8-bis(6′-bipyridinyl)-1,9,10-anthyridine (L3), are reported. Complexation of Ni(OAc)2 with L2 and L3 in trifluoroacetic acid provided the corresponding dinickel complexes [{Ni2(L2)(H2O)6(CF3COO)2}(CF3COO)2] (2) and [Ni2(L3)(CF3COO)4(H2O)] (3), respectively. Both complexes were characterized by spectroscopic methods and further confirmed by X-ray crystallography. Structural analyses of 2 and 3 revealed the Ni?Ni distances in the complexes to be 5.4086(6) and 5.0138(7) ?, respectively. The catalytic activities of complexes 2 and 3 toward the reduction of carboxylic acids were evaluated. It appears that complex 3 shows a good catalytic activity toward the reduction of carboxylates into the corresponding alcohols by diphenylsilane.
- Huang, Da-Wei,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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p. 8265 - 8271
(2016/06/09)
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- Method for preparing alcohol through catalytic hydrogenation reduction of carboxylate
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The invention discloses a method for preparing alcohol through catalytic hydrogenation reduction of a carboxylate compound with 2-(diphenylphosphinoethyl)-(5,6,7,8-tetrahydroquinolyl)amine as a ruthenium complex catalyst of ligand. The catalyst has high-efficiency catalysis activity on alkyl benzoate, aromatic esters and fatty esters. The preparation method is simple and has good stability, the catalysis activity of the catalyst is high, and the dosage of the catalyst is 0.025-0.005% of the mole of a substrate. The method can be used for producing alcohols, and has the advantages of simplicity, small pollution to environment, high yield and low cost. Most of carboxylate can be hydrogenated and reduced to form alcohols by using a complex represented by formula (1) with sodium borohydride as an additive, and the conversion number TOC can reach 50000; and a cocaalyst sodium borohydride is used to substitute most of alcoholic alkalis used as a catalyst in especially used in aromatic esters with electron-withdrawing substituent, so the cost is reduced, operation is simple, and industrial production is easy.
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Paragraph 0023; 0025; 0040
(2016/12/07)
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- Piano-stool benzothiazol-2-ylidene Ru(II) complexes for effective transfer hydrogenation of carbonyls
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Benzothiazolium bromides (NSHC.HBr) (1a-j) with a variety of alkyl chain or benzyl substituents on N atom were prepared. The synthesis of ruthenium(II) (NSHC) complexes, (2a–j) could be achieved by in situ deprotonation of benzothiazolium salts with Ag2O and [RuCl2(p-cymene)]2. They were characterized by 1H, 13C, 19F NMR, IR spectroscopy and elemental analysis. The molecular structures of 2d, 2e and 2g were ascertained by single-crystal X-ray diffraction studies. The catalytic properties of complexes, (2a–j), with electron-donating or -withdrawing groups were investigated in transfer hydrogenation (TH) of ketones, and aldehydes with good to excellent yields. The presence of the CH2(CH2)16CH3 or CH2C6F5 on the N atom of the benzothiazol-2-ylidene complexes (2g, 2j) showed the highest activity for TH reaction. The catalytic properties of the N-alkyl substituted ruthenium(II) (NSHC) complexes(2h–j) may be interpreted by micelle effects.
- Oru?, Zeynep ?pek,G?k, Lütfiye,Türkmen, Hayati,?ahin, Onur,Büyükgüng?r, Orhan,?etinkaya, Bekir
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- Mg-Prompted Polyfluoroarene C-H Functionalization: Formal Synthesis of Transfluthrin, Fenfluthrin, and Tefluthrin
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Directing group and transition metal free C-H bond functionalization of a simple molecule is an ideal but challenging chemical transformation. Herein, we report a general Mg-prompted approach to synthesize versatile polyfluoroaryl carbinols at ambient temperature via polyfluoroarene C-H bond addition to aldehydes, which featured excellent monoaddition selectivity and broad functional group compatibility. The usefulness of this practical and efficient method was demonstrated in gram-scale formal synthesis of pyrethroid insecticides transfluthrin, tefluthrin, and fenfluthrin.
- Jia, Xuejiao,Wang, Junya,Ding, Xue,Yang, Jun,Li, Nan,Zhao, Na,Huang, Zhiyan
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p. 10874 - 10882
(2015/11/18)
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- Direct Ruthenium-Catalyzed Hydrogenation of Carboxylic Acids to Alcohols
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The "green" reduction of carboxylic acids to alcohols is a challenging task in organic chemistry. Herein, we describe a general protocol for generation of alcohols by catalytic hydrogenation of carboxylic acids. Key to success is the use of a combination of Ru(acac)3, triphos and Lewis acids. The novel method showed broad substrate tolerance and a variety of aliphatic carboxylic acids including biomass-derived compounds can be smoothly reduced.
- Cui, Xinjiang,Li, Yuehui,Topf, Christoph,Junge, Kathrin,Beller, Matthias
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supporting information
p. 10596 - 10599
(2015/09/02)
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- Lipophilic M(α,α′-OC5H11)8phthalocyanines (M = H2 and Ni(II)): Synthesis, electronic structure, and their utility for highly efficient carbonyl reductions
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A lipophilic and electron-rich phthalocyanine (α,α′-n-OC5H11)8-H2Pc and its nickel(ii) complex (α,α′-n-OC5H11)8-Ni(ii)Pc have been synthesized and characterized. Detailed analyses of the electronic structure were carried out by spectroscopy, electrochemistry, spectroelectrochemistry, and TD-DFT calculations. A series of experiments demonstrate that the (α,α′-n-OC5H11)8-Ni(ii)Pc complex can be used as a catalyst for highly efficient carbonyl reductions.
- Jiang, Yu,Li, Minzhi,Liang, Xu,Mack, John,Wildervanck, Martijn,Nyokong, Tebello,Qin, Mingfeng,Zhu, Weihua
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p. 18237 - 18246
(2015/10/28)
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- Laccase-Mediator System for Alcohol Oxidation to Carbonyls or Carboxylic Acids: Toward a Sustainable Synthesis of Profens
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By combining two green and efficient catalysts, such as the commercially available enzyme laccase from Trametes versicolor and the stable free radical 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), the oxidation in water of some primary alcohols to the corresponding carboxylic acids or aldehydes and of selected secondary alcohols to ketones can be accomplished. The range of applicability of bio-oxidation is widened by applying the optimized protocol to the oxidation of enantiomerically pure 2-arylpropanols (profenols) into the corresponding 2-arylpropionic acids (profens), in high yields and with complete retention of configuration.
- Galletti, Paola,Pori, Matteo,Funiciello, Federica,Soldati, Roberto,Ballardini, Alberto,Giacomini, Daria
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p. 2684 - 2689
(2016/12/23)
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- Nonmetal catalyzed hydrogenation of carbonyl compounds
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Solutions of the Lewis acid B(C6F5)3 in 1,4-dioxane are found to effectively catalyze the hydrogenation of a variety of ketones and aldehydes. These reactions, the first to allow entirely metal-free catalytic hydrogenation of carbonyl groups under relatively mild reaction conditions, are found to proceed via a "frustrated Lewis pair" mechanism in which the solvent, a weak Bronsted base yet moderately strong donor, plays a pivotal role.
- Scott, Daniel J.,Fuchter, Matthew J.,Ashley, Andrew E.
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supporting information
p. 15813 - 15816
(2015/02/19)
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- Copper-catalyzed hydrodefluorination of fluoroarenes by copper hydride intermediates
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Breaking bad: Efficient copper-catalyzed C-F bond activation has been achieved by replacing fluorine with hydrogen. A copper hydride is proposed as the active intermediate, which proceeds through a nucleophilic attack on the fluorocarbon, as determined by experimental and theoretical results (see structure; C gray, H white, Cu light red, F light blue; distances in ?).
- Lv, Hongbin,Cai, Yuan-Bo,Zhang, Jun-Long
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supporting information
p. 3203 - 3207
(2013/04/23)
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- Identification of a marine NADPH-dependent aldehyde reductase for chemoselective reduction of aldehydes
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A putative aldehyde reductase gene from Oceanospirillum sp. MED92 was overexpressed in Escherichia coli. The recombinant protein (OsAR) was characterized as a monomeric NADPH-dependent aldehyde reductase. The kinetic parameters Km and kcat of OsAR were 0.89 ± 0.08 mM and 11.07 ± 0.99 s-1 for benzaldehyde, 0.04 ± 0.01 mM and 6.05 ± 1.56 s-1 for NADPH, respectively. This enzyme exhibited high activity toward a variety of aromatic and aliphatic aldehydes, but no activity toward ketones. As such, it catalyzed the chemoselective reduction of aldehydes in the presence of ketones, as demonstrated by the reduction of 4-acetylbenzaldehyde or the mixture of hexanal and 2-nonanone, showing the application potential of this marine enzyme in such selective reduction of synthetic importance.
- Li, Guangyue,Ren, Jie,Wu, Qiaqing,Feng, Jinhui,Zhu, Dunming,Ma, Yanhe
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- The catalytic promiscuity of a microbial 7α-hydroxysteroid dehydrogenase. Reduction of non-steroidal carbonyl compounds
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A thermostable 7α-hydroxysteroid dehydrogenase from Bacteroides fragilis ATCC 25285 was found to catalyze the reduction of various benzaldehyde analogues to their corresponding benzyl alcohols. The enzyme activity was dependent upon the substituent on the benzene ring of the substrates. Benzaldehydes with electron-withdrawing substituent usually showed higher activity than those with electron-donating groups. Furthermore, this enzyme was tolerant to some organic solvents. These results together with previous studies suggested that 7α-hydroxysteroid dehydrogenase from B. fragilis might play multiple functional roles in biosynthesis and metabolism of bile acids, and in the detoxification of xenobiotics containing carbonyl groups in the large intestine. In addition, its broad substrate spectrum offers great potential for finding applications not only in the synthesis of steroidal compounds of pharmaceutical importance, but also for the production of other high-value fine chemicals.
- Liu, Yang,Lv, Tong,Ren, Jie,Wang, Min,Wu, Qiaqing,Zhu, Dunming
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experimental part
p. 1136 - 1140
(2011/08/22)
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- A new synthetic route to polyfluorobenzyl alcohol
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The synthesis of polyfluorinated benzyl alcohol from pentafluorobenzoic acid has been developed. An economical and effective direct reduction method of polyfluorobenzoic acid by zinc borohydride is described.
- Zhang, Deyan,Chen, Zizhan,Cai, Huihua,Zou, Xinzhuo
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experimental part
p. 938 - 941
(2010/01/15)
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- Method for producing cyclopropanecarboxylates
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There is provided a method for producing a cyclopropanecarboxylate of formula (1): 1which comprises contacting a cyclopropanecarboxylate of formula (2): 2with a monohydroxy compound of formula (3):R7OH??(3)in the presence of a lithium compound of formula (4):R8OLi??(4),wherein R1, R2, R3, R4 and R5 each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted aryl group; R6 represents an alkyl group having 1 to 10 carbon atoms or a substituted or unsubstituted phenyl group; R7 and R8 do not simultaneously represent the same and each independently represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
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- Ester compounds
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Ester compounds shown by the formula: wherein R1represents a hydrogen atom, halogen atom, C1-C3alkyl group optionally substituted by halogen atom(s), C2-C3alkenyl group optionally substituted by halogen atom(s), C1-C3alkoxy group optionally substituted by halogen atom(s), C1-C3alkylthio group optionally substituted by halogen atom(s) or (C1-C3alkoxy)methyl group optionally substituted by halogen atom(s), n represents an integer of 1 to 4 and X represents a hydrogen atom or C1-C3alkyl group, have excellent pesticidal activity.
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- Ester compounds
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An ester compound represented by the formula: wherein R is a hydrogen atom, a C1-C3 alkyl group unsubstituted or substituted with one or more halogen atoms, an allyl group unsubstituted or substituted with one or more halogen atoms, or a propargyl group unsubstituted or substituted with one or more halogen atoms; and X is a hydrogen atom, a halogen atom, a C1-C3 alkyl group unsubstituted or substituted with one or more halogen atoms, a C2-C3 alkenyl group unsubstituted or substituted with one or more halogen atoms, a C2-C3 alkynyl group unsubstituted or substituted with one or more halogen atoms, a C1-C3 alkoxy group unsubstituted or substituted with one or more halogen atoms, a C1-C3 alkylthio group unsubstituted or substituted with one or more halogen atoms, or a C1-C3 alkoxymethyl group containing a C1-C3 alkoxy group unsubstituted or substituted with one or more halogen atoms, has an excellent pest-controlling effect.
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- Activation of aromatics towards oxygen by oxidative or reductive photosensitization
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Drastic conditions of photoexcitation are necessary to perform a direct activation of aromatic substrates towards 3O2.Two ways are proposed to increase this reactivity.For the substrates which are not bearing an electron attracting group, activation paradoxically consists in oxidizing the substrate by redox photosensitization with a recyclable electron acceptor.The use of a supported photosensitizer increases the selectivity in aldehyde formation.For the substrates bearing an electron attracting group the activation is achieved by reducing a benzyl halide with an electron donor photosensitizer.Keywords: reductive sensitization / oxidative sensitization / alkyl aromatics activation / benzyl halides activation / ET activation / dioxygen
- Julliard, M.,Chanon, M.
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p. 242 - 246
(2007/10/02)
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- Photosubstitution reactions on aromatic and heteroaromatic rings evidence for addition and substitution mechanism
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Irradiation of a cyclohexane solution of hexafluorobenzene in the presence of benzophenone resulted in both, substitution and addition products. Similar photoreaction has been observed by irradiation of hexafluorobenzene in some alcohols in the presence of benzophenone. The reaction of pentafluorobenzene with methanol or cyclohexane resulted in the substitution of a 2-or 4-fluoro atom, while the reaction of pentafluoroanisole resulted in the formation of o-, m- and p-isomers. Irradiation of a cyclohexane solution or of an alcohol solution of octafluoronaphthalene yielded 1- and 2-substituted products. On the other hand, the photosubstitution of fluorine atom in pentafluoropyridine took place exclusively at the position four, thus forming 4-cyclohexyl or 4-(1-hydroxyalkyl) substituted products.
- Sket, Boris,Zupan, Marko,Zupancic, Natasa,Pahor, Barbara
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p. 5029 - 5042
(2007/10/02)
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- THE SYNTHESIS AND REARRANGEMENT REACTIONS OF 2,3,4,5,6-PENTAFLUOROBENZYL METHYL SULPHOXIDE AND 1,1-BIS(PENTAFLUOROPHENYL)METHYL METHYL SULPHOXIDE
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2,3,4,5,6-Pentafluorobenzyl methyl sulphoxide (6) and 1,1-bis(pentafluorophenyl)methyl sulphoxide (9) were synthesised from hexafluorobenzene and sodium methylsulphinylmethide.Flash vapour phase thermolysis of (6) at 410 degC gave 2,2',3,3'4,4',5,5'6,6'-decafluorodibenzyl (11) whereas static vapour phase thermolysis at 140-190 deg C gave (11), 2,3,4,5,6-pentafluorobenzyl alcohol (12) and 2,2'3,3'4,4'5,5'6,6'-decafluorodibenzyl disulphide (13).Decaflourobenzophenone (14) and bis(pentafluorophenyl)methanol (15) are thermolysis products of compound (9) at 115-122 deg C, accompanied by 4-methanoyl-nonafluorobenzophenone (16) formed by the thermolysis of (19), the unisolated material derived from (9) by nucleophilic substitution of one para-fluorine by CH3SOCH2-.Central to the formation of (12), (13), (14), (15) and (16) are sulphenate esters formed by '1,2'-rearrangements, while homolysis of the C-SO(CH3) bond in (6) and dimerisation of the radical gives (11).
- Brooke, Gerald M.,Ferguson, J. A. K. Jamie
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p. 263 - 276
(2007/10/02)
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- Pyrimidine substituted-2,2-dimethylcyclopropane carboxylates useful for combating insect and acarine pests at a locus
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A compound of formula: STR1 wherein R2 represents an α-branched alkyl group containing from 3 to 6 carbon atoms, and R represents either (a) hydroxy, halo or alkoxy of up to six carbon atoms, or (b) the group --OR1 where R1 is the residue of an alcohol of formula R1 OH which forms an insecticidal ester with chrysanthemic acid, permethrin acid or cyhalothrin acid. The compounds have insecticidal and acaricidal properties.
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- Process for the preparation of halogenated benzoyl fluorides
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A process for the preparation of a halogenated benzoyl fluoride, which comprises contacting a halogenated benzotrifluoride of the formula STR1 in which m and n independently of one another represent an integer from 0 to 5, the sum of m and n being 5, with at least one sulphur compound of the formula STR2 in which X denotes fluorine, chlorine or hydroxyl and Y represents hydroxyl, or X and Y together denote an oxygen atom linked to the sulphur atom by a double bond, at an elevated temperature, and after reaction with the halogenated benzotrifluoride, removing the sulphur compound from the reaction mixture in the form of a compound of the formula STR3 in which X has the meaning given and Hal represents fluorine or chlorine, the reaction product is further reacted with potassium fluoride at an elevated temperature and under increased pressure.
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