- Unprecedented Halide-Ion Binding and Catalytic Activity of Nanoscale Anionic Metal Oxide Clusters
-
One halide ion (X?) can bind on the surface of nanoscale Anderson-type polyoxometalate (POMs) clusters [(n-C4H9)4N]3{AlMo6O18(OH)3[(OCH2)3CCH3]}, and form stable complexes in solution with binding constant K=1.53×103. Single-crystal structural analysis showed that this binding behavior occurs through multiple hydrogen bonding between X? and three hydroxy groups on the uncapped side of the cluster. This supramolecular interaction in the cluster systems means that their catalytic activities, evaluated from the oxidation of alcohols to aldehydes, can be switched upon the introduction of halide ions and water molecules. The halide ions work as inhibitors by blocking the active sites of the clusters while they can be re-activated by the addition of water.
- She, Shan,Li, Mu,Li, Qi,Huang, Zehuan,Wei, Yongge,Yin, Panchao
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-
Read Online
- A “universal” catalyst for aerobic oxidations to synthesize (hetero)aromatic aldehydes, ketones, esters, acids, nitriles, and amides
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Functionalized (hetero)aromatic compounds are indispensable chemicals widely used in basic and applied sciences. Among these, especially aromatic aldehydes, ketones, carboxylic acids, esters, nitriles, and amides represent valuable fine and bulk chemicals, which are used in chemical, pharmaceutical, agrochemical, and material industries. For their synthesis, catalytic aerobic oxidation of alcohols constitutes a green, sustainable, and cost-effective process, which should ideally make use of active and selective 3D metals. Here, we report the preparation of graphitic layers encapsulated in Co-nanoparticles by pyrolysis of cobalt-piperazine-tartaric acid complex on carbon as a most general oxidation catalyst. This unique material allows for the synthesis of simple, functionalized, and structurally diverse (hetero)aromatic aldehydes, ketones, carboxylic acids, esters, nitriles, and amides from alcohols in excellent yields in the presence of air.
- Bartling, Stephan,Beller, Matthias,Chandrashekhar, Vishwas G.,Jagadeesh, Rajenahally V.,Rabeah, Jabor,Rockstroh, Nils,Senthamarai, Thirusangumurugan
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supporting information
p. 508 - 531
(2022/02/11)
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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Method for reducing carboxylic acid into aldehyde compounds
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The invention discloses a method for reducing carboxylic acid into aldehyde compounds, and belongs to the field of organic chemical synthesis. Specifically, in an argon atmosphere, a carboxylic acid compound, a transition metal nickel compound, an anhydride compound, a ligand and a reducing agent are dissolved in an organic solvent, the mixture is heated and subjected to stirring reaction, after the reaction is finished, the pressure is reduced to remove the organic solvent, column chromatography separation is performed, and various aldehyde compounds are obtained. The method has the advantages of simple synthesis steps, mild reaction conditions, simplicity and easiness in operation, realization of successful reduction of the carboxylic acid compound into the aldehyde organic compounds, small use amount of the reaction catalyst, high product yield, and provision of a new approach for reduction of the carboxylic acid compound into the aldehyde compounds. Compared with a conventional method, the method has the advantages that raw materials are cheap, easy to obtain and environmentally friendly, substrate universality and functional group compatibility are improved, and the method hascertain innovativeness and unique research significance in organic synthesis methodology.
- -
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Paragraph 0031-0034
(2020/02/27)
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- AN IMPROVED ONE POT, ONE STEP PROCESS FOR THE HALOGENATION OF AROMATICS USING SOLID ACID CATALYSTS
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The present invention disclosed an improved one pot, one step process for halogenation of compound of formula (II) to afford corresponding halogenated compound of formula (I) having improved yield and increased selectivity under very mild conditions.
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Page/Page column 0047; 0048
(2019/04/18)
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- Single-Atom-Based Vanadium Oxide Catalysts Supported on Metal-Organic Frameworks: Selective Alcohol Oxidation and Structure-Activity Relationship
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We report the syntheses, structures, and oxidation catalytic activities of a single-atom-based vanadium oxide incorporated in two highly crystalline MOFs, Hf-MOF-808 and Zr-NU-1000. These vanadium catalysts were introduced by a postsynthetic metalation, a
- Otake, Ken-Ichi,Cui, Yuexing,Buru, Cassandra T.,Li, Zhanyong,Hupp, Joseph T.,Farha, Omar K.
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p. 8652 - 8656
(2018/07/09)
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- Highly Productive Oxidative Biocatalysis in Continuous Flow by Enhancing the Aqueous Equilibrium Solubility of Oxygen
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We report a simple, mild, and synthetically clean approach to accelerate the rate of enzymatic oxidation reactions by a factor of up to 100 when compared to conventional batch gas/liquid systems. Biocatalytic decomposition of H2O2 is used to produce a soluble source of O2 directly in reaction media, thereby enabling the concentration of aqueous O2 to be increased beyond equilibrium solubility under safe and practical conditions. To best exploit this method, a novel flow reactor was developed to maximize productivity (g product L?1 h?1). This scalable benchtop method provides a distinct advantage over conventional bio-oxidation in that no pressurized gas or specialist equipment is employed. The method is general across different oxidase enzymes and compatible with a variety of functional groups. These results culminate in record space-time yields for bio-oxidation.
- Chapman, Michael R.,Cosgrove, Sebastian C.,Turner, Nicholas J.,Kapur, Nikil,Blacker, A. John
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supporting information
p. 10535 - 10539
(2018/08/17)
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- N-Iodosuccinimide (NIS) in Direct Aromatic Iodination
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N-Iodosuccinimide (NIS) in pure trifluoroacetic acid (TFA) offers a time-efficient and general method for the iodination of a wide range of mono- and disubstituted benzenes at room temperature, as demonstrated in this paper. The starting materials were generally converted into mono-iodinated products in less than 16 hours at room temperature, without byproducts. A few deactivated substrates needed addition of sulfuric acid to increase the reaction rate. Another exception was methoxybenzenes that preferentially were iodinated by NIS in acetonitrile with only catalytic amounts of TFA.
- Bergstr?m, Maria,Suresh, Ganji,Naidu, Veluru Ramesh,Unelius, C. Rikard
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p. 3234 - 3239
(2017/06/21)
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- Preparation of Aldehydes by Oxidation of Benzylic Amines with Selectfluor (F-TEDA-BF4)
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Aldehydes are obtained by mild oxidation of benzylic amines with Selectfluor. The results are compared favorably with the Polonovski-like process using hypervalent iodine.
- Hauser, Anett,Bohlmann, Rolf
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supporting information
p. 1870 - 1872
(2016/07/16)
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- Isoquinolinium Dichromate and Chlorochromate as Efficient Catalysts for Oxidative Halogenation of Aromatic Compounds under Acid-Free Conditions
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Isoquinolinium dichromate and isoquinolinium chlorochromate were found as efficient catalysts to trigger oxidative bromination and iodination of aromatic hydrocarbons with KBr/KI and KHSO4 under acid-free conditions. Reaction times reduced highly significantly under sonication, followed by corresponding mono bromo derivatives in very good yield with high regioselectivity.
- Rao, A. Sambashiva,Rajanna,Reddy, K. Rajendar,Kulkarni, Subhash
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p. 832 - 837
(2016/02/12)
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- Heterogeneous oxidation of alcohols with hydrogen peroxide catalyzed by polyoxometalate metal–organic framework
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HSiW-MOF, PMo-MOF, HPMo-MOF and PW-MOF were synthesized and characterized by elemental analysis, UV–Vis, FT-IR, cyclic voltammetry and XRD. These compounds were used as catalyst for the selective oxidation of alcohols by hydrogen peroxide. Within them, PW-MOF showed a higher catalytic activity compared to other catalysts in a similar reaction condition. Therefore, PW-MOF catalyst system was successfully used for the selective oxidation of the benzylic, linear and secondary alcohols to the corresponding aldehydes and ketones. Also, allylic alcohols were converted to the corresponding aldehydes with high conversion and significant selectivity. Moreover, PW-MOF was stable to leaching, behaved as true heterogeneous catalysts, easily recovered by filtration, and reused four times with the preserve of the catalytic performance.
- Babahydari, Ali Kazemi,Fareghi-Alamdari, Reza,Hafshejani, Shahrbanou Moradpour,Rudbari, Hadi Amiri,Farsani, Mostafa Riahi
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p. 1463 - 1470
(2016/07/06)
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- Palladium-catalyzed synthesis of aldehydes from aryl halides and tert-butyl isocyanide using formate salts as hydride donors
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An efficient one-pot palladium-catalyzed hydroformylation of aryl halides to produce aromatic aldehydes has been achieved, employing tert-butyl isocyanide as a C1 resource and formate salt as a hydride donor without any additional bases. Characterized by its mild reaction conditions, easy operation and lower toxicity, this reaction can tolerate a wide array of functional groups with moderate to excellent yields.
- Zhang, Ying,Jiang, Xiao,Wang, Jin-Mei,Chen, Jing-Lei,Zhu, Yong-Ming
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p. 17060 - 17063
(2015/03/30)
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- POLYMER PRECURSORS OF RADIOLABELED COMPOUNDS, AND METHODS OF MAKING AND USING THE SAME
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One aspect of the present invention relates to novel compounds that can be used to prepare radiolabeled compounds in an effective manner. A second aspect of the present invention relates to a method of synthesizing radiolabeled compounds.
- -
-
Paragraph 0237
(2015/09/23)
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- Synthesis, characterization and catalytic performance of a Fe polyoxometalate/silica composite in the oxidation of alcohols with hydrogen peroxide
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Fe(III) substituted Keggin type polyoxometalate in amorphous silica matrix, (n-C4H9)4N)4[PW 11FeO39]/SiO2 (PWFe/SiO2), has been synthesized by sol-gel method. The synthesized PWFe/SiO2 composite was characterized by various analytical and spectroscopic techniques. Results indicated that the primary Keggin structure remain after incorporation in silica matrix. As a heterogeneous catalyst, PWFe/SiO2 composite showed an elevated catalytic activity and selectivity with high to excellent yields for oxidation of alcohols into aldehydes by H2O2. The stability and reusability of the catalyst was very high, so these composites are suitable for the heterogeneous catalysis by hydrogen peroxide.
- Farsani, Mostafa Riahi,Yadollahi, Bahram
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- Facile, mild and selective silica sulfuric acid catalyzed oxidation of benzylalcohols to benzaldehyde derivatives by potassium peroxodisulfate
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An efficient, facile, and mild oxidation of a variety of primary benzylic alcohols to the corresponding aldehydes with potassium peroxodisulfate in the presence of a catalytic amount of sodium chloride and silica sulfuric acid (SSA) in acetonitrile as solvent is reported. It is a renowned fact that potassium peroxodisulfate acts as a powerful oxidizing agent and the control of conditions is difficult. For this purpose, SSA as a mild, efficient and reusable solid acid catalyst was used to afford the carbonyl compounds in excellent yields and short time. The structure of all of the resulting products was confirmed by FT-IR spectroscopy.
- Badri, Rashid,Alizadeh-haddad, Alireza,Adlu, Maryam,Mohammadi, Mohammad Kazem
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p. 131 - 136
(2013/08/24)
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- Mild oxidation of benzylic amines into aldehydes using an oxidative Polonovski-like process
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A chemoselective and environmentally benign oxidation of benzylic amines into aldehydes mediated by a hypervalent iodine reagent has been developed. This mild oxidative version of the Polonovski process may be selectively carried out in the presence of several functionalities including a free alcohol and provides new synthetic opportunities as a masked aldehyde segment. Georg Thieme Verlag Stuttgart · New York.
- Desjardins, Samuel,Jacquemot, Guillaume,Canesi, Sylvain
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experimental part
p. 1497 - 1500
(2012/07/28)
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- Kinetics and oxidation of substituted benzyl alcohols by phenyliodoso acetate
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Oxidation of benzyl alcohol and some meta- and para- substituted alcohols by phenyliodoso acetate (PIA) in t-butyl alcohol-water medium (50:50) leads to the formation of corresponding benzaldehyde. The stoichiometry of the reaction was found to be 1:1. The reaction was first order each in substrate and oxidant concentrations. This reaction was studied at four different temperatures and the activation parameters were calculated. Correlation analysis was carried out using Taft's and Swain's dual substituent parameter (DSP) equation. The rate data of meta- compounds showed good correlation with (F,R) values, para-substituted benzyl alcohols showed good correlation with σIσR + A suitable mechanism has been proposed.
- Girija,Aruna
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experimental part
p. 264 - 268
(2012/02/02)
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- Synthesis of fluorescence-labelled glycosidic prodrugs based on the cytotoxic antibiotic duocarmycin
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The synthesis of the glycosidic prodrugs (1S)-30a, (1S,10R)-30b and (1S,10R)-32 labelled with different fluorescence dyes at different positions at the aromatic A-ring in 2 is described; the compounds are structurally based on the cytotoxic antibiotic duocarmycin SA. For binding, the amino compounds (1S)-3a and (1S,10R)-3b were treated with the commercially available succinimides of the dyes 5-SFX (29) and D10162 (31), respectively. Fluorescence-labelled compounds can be used for verification of interaction with cellular targets on the molecular level by use of confocal laser scanning microscopy for cell cultures and the Explore-Optics instrument (GE) for mice. The described fluorescence-labelled glycosidic prodrugs based on the cytotoxic antibiotic duocarmycine SA have high potential for selective treatment of cancer. Copyright
- Tietze, Lutz F.,Behrendt, Frank,Major, Felix,Krewer, Birgit,Von Hof, J. Marian
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supporting information; experimental part
p. 6909 - 6921
(2011/02/23)
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- Biocatalytic oxidation of benzyl alcohol to benzaldehyde via hydrogen transfer
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Various types of biocatalysts like oxidases, alcohol dehydrogenases, and microbial cells were tested for the oxidation of benzyl alcohol. Oxidases in combination with molecular oxygen led to low conversion. Alcohol dehydrogenases and microbial cells were tested in a hydrogen transfer reaction employing acetaldehyde, chloroacetone, and acetone as hydrogen acceptor. Excellent conversion (95%) could be achieved employing lyophilised cells of Janibacter terrae DSM 13953 at a substrate concentration of 97 mM.
- Orbegozo, Thomas,Lavandera, Iván,Fabian, Walter M.F.,Mautner, Barbara,de Vries, Johannes G.,Kroutil, Wolfgang
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scheme or table
p. 6805 - 6809
(2010/01/06)
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- tert-Butyldimethylsilyloxytrichloromethylmethane-readily accessible and robust protecting group for (hetero)aryl aldehydes
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The tert-butyldimethylsilyloxytrichloromethylmethane (TBSTCM) substituent serves as a readily accessible masking group for aromatic and heteroaromatic aldehydes. The TBSTCM substituent is compatible with a range of common reagents and offers several strategic advantages over alternative aldehyde protecting groups.
- Cafiero, Lauren R.,Snowden, Timothy S.
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p. 2844 - 2847
(2008/09/20)
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- Tetraalkylammonium dichloroiodates as iodinating agents: Absence of activity in solid phases and superelectrophilic activity in sulfuric acid
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In contrast to published results, tetraalkylammonium dichloroiodates (Alk4N+ICl2-) cannot be iodinating reagents for arenes in solvent-free conditions. Nevertheless, tetraalkylammonium dichloroiodates in sulfuric acid solutions or in the presence of Ag 2SO4 in H2SO4 possess superelectrophilic properties and act as very convenient and efficient iodinating agents for deactivated arenes. Georg Thieme Verlag Stuttgart.
- Filimonov, Victor D.,Semenischeva, Nadya I.,Krasnokutskaya, Elena A.,Ho, Yun Hwang,Chi, Ki-Whan
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p. 401 - 404
(2008/09/20)
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- Self-assembly of shape-persistent hexagonal macrocycles with trimeric bis(terpyridine)-FeII connectivity
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A novel family of bis(terpyridinyl) ligands was designed and constructed by facile Pd-catalyzed coupling reactions. Subsequent terpyridine-transition-metal complexation facilitated self-assembly resulting in a hexagonal, trimeric series of metallomacrocycles. An enhanced solubility of a macrocycle and its bis(terpyridine) precursor possessing elongated, alkyl-branched phenylacetylene spacers was achieved by the incorporation of dodecyloxy moieties. The characterization of the metallomacrocycles included 1H, 13C NMR, and UV spectroscopy and mass spectrometry, as well as electrochemistry. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Li, Sinan,Moorefield, Charles N.,Wang, Pingshan,Shreiner, Carol D.,Newkome, George R.
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experimental part
p. 3328 - 3334
(2009/04/06)
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- Superactivity and dual reactivity of the system N-iodosuccinimide-H 2SO4 in the iodination of deactivated arenes
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Dissolution of N-iodosuccinimide in sulfuric acid gives rise to electrophilic iodine-containing species which are capable of successfully iodinating aromatic compounds with electron-withdrawing substituents in the temperature range from 0 to 20°C. The iodination in sulfuric acid is effected by both protonated N-iodosuccinimide and IOS(O)(OH+)OH intermediate.
- Chaikovskii,Filimonov,Skorokhodov,Ogorodnikov
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p. 1278 - 1281
(2008/03/27)
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- 1,3-Diiodo-5,5-dimethylhydantoin-An efficient reagent for iodination of aromatic compounds
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1,3-Diiodo-5,5-dimethylhydantoin in organic solvents successfully iodinates alkylbenzenes, aromatic amines, and phenyl ethers. The reactivity of electrophilic iodine is controlled by acidity of the medium. Superelectrophilic iodine generated upon dissolution of 1,3-diiodo-5,5-dimethylhydantoin in sulfuric acid readily reacts with electron-deficient arenes at 0 to 20°C with formation of the corresponding iodo derivatives in good yields. The structure of electrophilic iodine species generated from 1,3-diiodo-5,5- dimethylhydantoin in sulfuric acid is discussed.
- Chaikovskii,Filimonov,Funk,Skorokhodov,Ogorodnikov
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p. 1291 - 1296
(2008/03/27)
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- Oxidative iodination of deactivated arenes in concentrated sulfuric acid with I2/NaIO4 and KI/NaIO4 iodinating systems
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Deactivated arenes were mono- or diiodinated with strong electrophilic I+ reagents, which were prepared from NaIO4 and either I2 or KI in concentrated H2SO4 (minimum 95% by weight). In general a small excess of the dark brown iodinating solution was used (1.1/1.5 equivalents, for nitrobenzene two equivalents was required). The iodinations were conducted at 25-30 °C with a reaction time of 1-2 hours using either a 'direct' or an 'inverse' method of aromatic iodination to give mono- or diiodinated pure products in 31-91% optimized yields. Georg Thieme Verlag Stuttgart.
- Kraszkiewicz, Lukasz,Sosnowski, Maciej,Skulski, Lech
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p. 1195 - 1199
(2007/10/03)
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- Aryl-and heteroaryl-substituted tetrahydroisoquinolines and use thereof to block reuptake of norepinephrine, dopamine and serotonin
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The present invention relates to a method of treating disorders by administering to a patient in need of such treatment a therapeutically effective amount of a compound of formula (I): wherein R1-R8 are as described herein, R4 being aryl or heteroaryl.
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Page/Page column 14-15
(2008/06/13)
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- CELL TARGETING CONJUGATES
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The present invention relates to cell targeting conjugates and in particular, but not exclusively, to methods of their use in selectively eliminating and in selectively imaging target cells. The invention also relates to processes for production of the conjugates and to intermediate compounds that may be used in production of a specific class of cell targeting conjugates. In one embodiment there is provided a cell targeting conjugate comprising the following components that are covalently conjugated via a linker that is degradable within the target cells: i) a DNA minor groove binding ligand incorporating an effective Auger electron-emitting and/or gamma-emitting and/or positron-emitting atom or photoactive moiety; ii) a target cell specific protein or peptide that is capable of internalisation by target cells.
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Page/Page column 41-42
(2008/06/13)
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- METHODS FOR TREATING RETINOID RESPONSIVE DISORDERS USING SELECTIVE INHIBITORS OF CYP26A AND CYP26B
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The invention provides methods for treating an individual having a retinoid responsive disorder. In one embodiment, a method involves administering to the individual an effective amount of a selective CYP26B inhibitor, the selective CYP26B inhibitor having at least 10-fold selectivity for CYP26B relative to CYP26A. In another embodiment, a method involves administering to the individual an effective amount of a selective CYP26A inhibitor, the selective CYP26A inhibitor having a chemical formula set forth in the specification. The invention further provides screening methods for identifying a selective CYP26A inhibitor or selective CYP26B inhibitor.
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Page/Page column 78
(2008/06/13)
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- COMPOUNDS HAVING SELECTIVE CYTOCHROME P450RAI-1 OR SELECTIVE CYTOCHROME P450RAI-2 INHIBITORY ACTIVITY AND METHODS OF OBTAINING THE SAME
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Compounds of formulas 1 through 17 provided in the specification specifically or selectively inhibit either the cytochrome P450RAI-1 enzyme or the cytochrome P450RAI-2 enzyme.
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Page/Page column 49
(2010/02/12)
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- Easy, inexpensive and effective oxidative iodination of deactivated arenes in sulfuric acid
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Two 'model' deactivated arenes, benzoic acid and nitrobenzene, were effectively monoiodinated within 1 h at 25-30 °C, with strongly electrophilic I+ reagents, prior prepared from diiodine and various oxidants (CrO3, KMnO4, active MnO2, HIO 3, NaIO3, or NaIO4) in 90% (v/v) concd sulfuric acid (ca. 75 mol% H2SO4). Next, an I2/ NaIO3/90% (v/v) concd H2SO4 exemplary system was used to effectively mono- or diiodinate a number of deactivated arenes. All former papers dealing with the direct iodination of deactivated arenes are briefly reviewed.
- Kraszkiewicz, Lukasz,Sosnowski, MacIej,Skulski, Lech
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p. 9113 - 9119
(2007/10/03)
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- NOVEL LIGANDS THAT ARE ANTAGONISTS OF RAF RECEPTORS, PROCESS FOR PREPARING THEM AND USE THEREOF IN HUMAN MEDICINE AND IN COSMETICS
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The invention relates to novel compounds corresponding to formula (I) below: and to the method for preparing them, and to their use in pharmaceutical compositions intended for use in human or veterinary medicine, or alternatively in cosmetic compositions.
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- Double elimination protocol for convenient synthesis of dihalodiphenylacetylenes: Versatile building blocks for tailor-made phenylene-ethynylenes
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Dihalodiphenylacetylenes are conveniently synthesized by a double elimination reaction of β-substituted sulfones which are readily obtained from halogen-substituted benzyl sulfone and benzaldehyde derivatives. Halogens can be incorporated at any desired positions in the diphenylacetylene skeleton simply by choosing the substitution position of the halogen on the aromatic rings of the starting compounds. The diphenylacetylenes with different halogen substituents thus obtained undergo sequential carbon-carbon bond formations due to the different reactivities of the halogens. Thus, various moieties can be incorporated on the diphenylacetylene skeleton at whichever positions so that a variety of tailor-made phenylene-ethynylenes with regulated structure and composition could be designed.
- Orita, Akihiro,Miyamoto, Kazuhiko,Nakashima, Mikio,Ye, Fangguo,Otera, Junzo
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p. 767 - 776
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzyl alcohols by [bis(trifluoroacetoxy)iodo]benzene
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The oxidation of substituted benzyl alcohols by bis(trifluoroacetoxy)iodo] benzene in aqueous acetic acid solution results in the formation of the corresponding benzaldehydes. The reaction is first order with respect to each of the alcohol, TFAIB and hydrogen ions. The oxidation of [1,1-2H 2]benzyl alcohol exhibited the presence of a substantial primary kinetic isotope effect, indicating the cleavage of the α-C-H bond in the rate-determining step. Increase in the amount of water, in the solvent mixture of acetic acid and water, results in a decrease of the reaction rate. The analysis of the substituent effect in terms of Charton's LDR equation yielded an excellent correlation with negative reaction constants. A mechanism involving a hydride-ion transfer in the rate-determining step has been proposed.
- Kansara, Alpna,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 581 - 584
(2007/10/03)
-
- Catalytic Conversions in Water. Part 23: Steric Effects and Increased Substrate Scope in the Palladium-Neocuproine Catalyzed Aerobic Oxidation of Alcohols in Aqueous Solvents
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The steric influence of substituents on the 2-and 9-positions of phenanthroline in the (2,9-R2-1,10-phenanthroline)palladium(II)- catalyzed aerobic oxidation of 2-hexanol was investigated by means of high throughput experimentation. (Neocuproine)Pd-(OAc)2 (R=CH 3) was found to be a highly active catalyst for alcohol oxidation in 1:1 water/DMSO mixtures. The catalyst is unique in that it tolerates water, polar co-solvents and a wide variety of functional groups in the alcohol. Turn-over frequencies of > 1500 h-1 were achieved and a series of alcohols was oxidised with 0.1 to 0.5 mol % of catalyst.
- Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Hoogenraad, Marcel,Verspui, Goeran,Sheldon, Roger A.
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p. 1341 - 1352
(2007/10/03)
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- Catalytic Conversions in Water. Part 22: Electronic Effects in the (Diimine)palladium(II)-Catalysed Aerobic Oxidation of Alcohols
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The electronic effects in the (diimine)Pd-(II)-catalysed aerobic oxidation of alcohols were investigated from the viewpoint of both the catalyst and the alcohol. A 'push-pull' mechanism is operative, where both electron-donating substituents on the benzyl alcohol (ρ = -0.58) and electron-withdrawing groups on the 4,4′-disubstituted-2,2′-bipyridine ligand (ρ = +0.18) increase the reaction rate. The results indicate partial reduction of the palladium centre in the transition state of the rate-limiting step.
- Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Hoogenraad, Marcel,Verspui, Goeran,Sheldon, Roger A.
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p. 497 - 505
(2007/10/03)
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- Tetramethylammonium dichloroiodate: An efficient and environmentally friendly iodination reagent for iodination of aromatic compounds under mild and solvent-free conditions
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Tetramethylammonium dichloroiodate (1, TMADCI) as a mild and efficient iodination reagent was prepared. Iodination of different aromatic compounds with this reagent takes place fast and with high yields under solvent-free conditions.
- Hajipour, Abdol R.,Arbabian, Marty,Ruoho, Arnold E.
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p. 8622 - 8624
(2007/10/03)
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- Synthesis of combinatorial libraries of compounds reminiscent of natural products
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The present invention provides complex compounds reminiscent of natural products and libraries thereof, as well as methods for their production. The inventive compounds and libraries of compounds are reminiscent of natural products in that they contain one or more stereocenters, and a high density and diversity of functionality. In general, the inventive libraries are synthesized from diversifiable scaffold structures, which are synthesized from readily available or easily synthesizable template structures. In certain embodiments, the inventive compounds and libraries are generated from diversifiable scaffolds synthesized from a shikimic acid based epoxyol template. In other embodiments, the inventive compounds and libraries are generated from diversifiable scaffolds synthesized from the pyridine-based template isonicotinamide. The present invention also provides a novel ortho-nitrobenzyl photolinker and a method for its synthesis. Furthermore, the present invention provides methods and kits for determining one or more biological activities of members of the inventive libraries. Additionally, the present invention provides pharmaceutical compositions containing one or more library members.
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- Iodine(V) reagents in organic synthesis. Part 4. o-Iodoxybenzoic acid as a chemospecific tool for single electron transfer-based oxidation processes
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o-Iodoxybenzoic acid (IBX), a readily available hypervalent iodine(V) reagent, was found to be highly effective in carrying out oxidations adjacent to carbonyl functionalities (to form α, β-unsaturated carbonyl compounds) and at benzylic and related carbon centers (to form conjugated aromatic carbonyl systems). Mechanistic investigations led to the conclusion that these new reactions are initiated by single electron transfer (SET) from the substrate to IBX to form a radical cation which reacts further to give the final products. Fine-tuning of the reaction conditions allowed remarkably selective transformations within multifunctional substrates, elevating the status of this reagent to that of a highly useful and chemoselective oxidant.
- Nicolaou,Montagnon,Baran,Zhong
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p. 2245 - 2258
(2007/10/03)
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- Sulfoximine version of double elimination protocol for synthesis of chiral acetylenic cyclophanes
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A new strategy for constructing enantiopure acetylenic cyclophanes is described on the basis of one-pot double elimination reaction starting from dialdehydes and bis(sulfoximine)s. In this case, the conventional sulfone protocol affords poorer yields of t
- Orita, Akihiro,De, Lie An,Nakano, Takehiko,Yaruva, Jayamma,Ma, Nianchun,Otera, Junzo
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p. 2005 - 2010
(2007/10/03)
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- Oxidation of benzyl alcohol by pyridinium dichromate in acetonitrile. Using the paralmeta ratio of substituent effects for mechanism elucidation
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Rate constants were measured for the oxidation reaction of benzyl alcohol and twenty-five ortho-, recta- and para-monosubstituted derivatives in the temperature range 293-323 K at intervals of 10 K. The kinetics were followed spectrophotometrically in dry acetonitrile acidified with trichloroacetic acid (TCA) using pyridinium dichromate (PDC) as oxidising agent under pseudo-first-order conditions with respect to PDC. Benzaldehyde is the only oxidation product and no reaction takes place without TCA. From good linear Eyring plots activation enthalpies Δ?H° and entropies Δ?S° are calculated. For ortho-substituted benzyl alcohols high Δ?H° values and small negative Δ?S° values point to an ortho effect on the rate-determining step. Using the tetralinear approach to substituent effects, the average value λ = 1.09 ± 0.05 for the para/meta ratio of inductive or Electra effects is obtained and negative Hammett reaction constants decreasing in magnitude with increasing temperature are found. A mechanism implicating the prior acid-catalysed formation of neutral benzyl hydrogen dichromate ester followed by intramolecular proton transfer is proposed. Modelling of parameter λ in terms of the electrostatic theory showed its experimental value to be consistent with the ratio of electric potentials generated in the immediate vicinity of the nearest chromium atom by dipolar substituents introduced in the aromatic ring on para and meta positions. At a molecular level the oxidative, rate-determining step is suggested to be triggered by the retraction or shrinkage of electron pairs from sigma bonds in Cr2VI species to non-bonding orbitals in unstable CrIV-O-CrVI species. In contrast with past interpretations, an electrochemical approach is used to explain negative values for the Hammett reaction constant.
- Kabilan,Girija,Reis, Joao Carlos R.,Segurado, Manuel A.P.,De Oliveira, Jaime D. Gomes
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p. 1151 - 1157
(2007/10/03)
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- The effect of vinyl esters on the enantioselectivity of the lipase-catalysed transesterification of alcohols
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The enantioselectivity of the lipase from Pseudomonas cepacia (PCL) in the transesterification of 2-phenyl-1-propanol 1 was studied using a series of vinyl 3-arylpropanoates as acyl donors. The most enantioselective transesterification reaction of the alcohol was attained by using vinyl 3-(p-iodophenyl)- or 3-(p-trifluoromethylphenyl)propanoates, with enantiomer ratios, E, of 116 and 138, respectively. Vinyl 3-phenylpropanoate was also effective for the resolution of 1 mediated by lipases from P. fluorescens and porcine pancreas and for the PCL-catalysed transesterification of several 2-phenyl-1-alkanols. The enantiomeric resolution of 1 was practically carried out by the first enantioselective transesterification using PCL and vinyl 3-(p-iodophenyl)propanoate to afford (R)-1 and then the enantioselective hydrolysis of the resultant ester to afford (S)-1.
- Kawasaki, Masashi,Goto, Michimasa,Kawabata, Shigeki,Kometani, Tadashi
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p. 585 - 596
(2007/10/03)
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- 2,4,6,8-Tetraiodoglycoluril in sulfuric acid as a new powerful reagent for iodination of deactivated arenes
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Deactivated arenes are iodinated readily at 0°C by the action of 2,4,6,8-tetraiodoglycoluril in sulfuric acid to give the iodoarenes in generally good yields. (C) 2000 Elsevier Science Ltd.
- Chaikovski,Filimonov,Yagovkin,Kharlova
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p. 9101 - 9104
(2007/10/03)
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- Superactive iodination reagent on a base of iodine chloride and silver sulfate
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After reaction of ICl and Ag2SO4 in sulfuric acid and separation of resulting AgCl a stable solution is formed, containing very active forms of electrophilic iodine. This solution has a powerful iodination ability with respect to aromatic compounds. Deactivated arenes are iodinated easily and in mild conditions by action of this new reagent in generally good yields of the iodoarenes.
- Chaikovski, Vitold K.,Kharlova, Tatjana S.,Filimonov, Victor D.,Saryucheva, Tamara A.
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p. 748 - 750
(2007/10/03)
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- Conformationally restricted paclitaxel analogues: Macrocyclic mimics of the 'hydrophobic collapse' conformation
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Conformationally restricted macrocyclic analogues of paclitaxel were prepared, by connecting the 3'-phenyl group the 2-benzoate moiety with two-atom tethers to mimic the 'hydrophobic collapse' paclitaxel conformation. The analogues did not show activity in a tubulin assembly assay.
- Boge, Thomas C.,Wu, Zhi-Jun,Himes, Richard H.,Vander Velde, David G.,Georg, Gunda I.
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p. 3047 - 3052
(2007/10/03)
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- Synthesis and preliminary evaluation of a library of polycyclic small molecules for use in chemical genetic assays
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(-)-Shikimic acid, 3, was converted into both enantiomers of epoxycyclohexenol carboxylic acid, 7, which were attached to a solid support via a photocleavable linker. Tandem acylation-1,3-dipolar cycloaddition with nitrones 11a-g yielded tetracyclic templates 12a-g. After development of several efficient coupling reactions of iodobenzyl tetracycles 12b-d and completion of extensive validation protocols, a splitpool synthesis yielded a binary encoded library calculated to contain 2.18 million polycyclic compounds. These compounds are compatible with miniaturized cell-based 'forward' chemical genetic assays designed to explore biological pathways and 'reverse' chemical genetic assays designed to explore protein function. As a simple illustration of the potential of these compounds, several were shown to activate a TGF-β-responsive reporter gene in mammalian cells.
- Tan, Derek S.,Foley, Michael A.,Stockwell, Brent R.,Shair, Matthew D.,Schreiber, Stuart L.
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p. 9073 - 9087
(2007/10/03)
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- Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols by benzyltrimethylammonium dichloroiodate
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Oxidation of benzyl alcohols by benzyltimethylammonium dichloroiodate (BTMACI) in glacial acetic acid, in the presence of zinc chloride, resulted in the formation of corresponding benzaldehydes. The reaction is first order with respect to BTMACI, the alcohol and zinc chloride. The oxidation of α,α-dideuteriobenzyl alcohol exhibited a primary kinetic isotope effect (ko/kD=5.21 at 318 K). Addition of benzyltrimethylammonium chloride enhances the reaction rate. It is proposed that the reactive oxidizing species is + -. The rate constants of oxidation were subjected to correlation analysis using various single- and multi-parametric equations. The best correlation is obtained with Charton's LDR and LDRS equations. The polar regression coefficients are negative, indicating the formation of a cationic species in the rate-determining step. The reaction is subject to steric acceleration by ortho-substituent. A mechanism involving a hydride-ion transfer from the alcohol to the oxidant in the rate-determining step has been postulated.
- Rao, P. Surya Chandra,Suri, Deepa,Kothari, Soona,Banerji, Kalyan K.
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p. 2251 - 2272
(2007/10/03)
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- Correlation analysis of structure and reactivity in the oxidation of substituted benzyl alcohols by bis(2,2' -bipyridyl) copper(II) permanganate
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The oxidation of substituted benzyl alcohols by bis(2,2'-bipyridyl) copper(II) permanganate (BBCP), leading to the corresponding benzaldehydes is first-order with respect to BBCP. Michaelis-Menten type kinetics were observed with respect to the alcohols. The oxidation of a a-dideuteriobenzyl alcohol indicated the presence of a substantial kinetic isotope effect. The rates of oxidation of meta- and para-substituted benzyl alcohols were correlated in terms of Charton's triparametric LDR equation whereas ortho-substituted benzyl alcohols were correlated with a four parametric LDRS equation. The results of correlation analyses point to an electron-deficient reaction center in the transition state.
- Vyas,Kothari,Banerji
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