cas 1460-05-5, (4-NITRO-PHENYL)-ACETALDEHYDE

Articles about 1460-05-5Total 39 be found

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β-Lactone formation during product release from a nonribosomal peptide synthetase
Nonribosomal peptide synthetases (NRPSs) are multidomain modular biosynthetic assembly lines that polymerize amino acids into a myriad of biologically active nonribosomal peptides (NRPs). NRPS thioesterase (TE) domains employ diverse release strategies for off-loading thioester-tethered polymeric peptides from termination modules typically via hydrolysis, aminolysis, or cyclization to provide mature antibiotics as carboxylic acids/esters, amides, and lactams/lactones, respectively. Here we report the enzyme-catalyzed formation of a highly strained β-lactone ring during TE-mediated cyclization of a β-hydroxythioester to release the antibiotic obafluorin (Obi) from an NRPS assembly line. The Obi NRPS (ObiF) contains a type I TE domain with a rare catalytic cysteine residue that plays a direct role in β-lactone ring formation. We present a detailed genetic and biochemical characterization of the entire Obi biosynthetic gene cluster in plant-associated Pseudomonas fluorescens ATCC 39502 that establishes a general strategy for β-lactone biogenesis.
Schaffer, Jason E,Reck, Margaret R,Prasad, Neha K,Wencewicz, Timothy A
p. 737 - 744
(2017)
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Synthesis method of phenylacetaldehyde derivative
The present invention discloses a synthesis method of phenylacetaldehyde derivative, a benzaldehyde derivative is adopted as a raw material, an intermediate 2-methoxyvinylphenyl derivative is obtained through synthesis, then the phenylacetaldehyde derivative is obtained through synthesis, and the substituent group R of the benzaldehyde derivative includes but is not limited to m-methyl, m-ethyl, m-nitrile group, p-methyl, o-methyl, o-nitro and 2, 6-dimethyl. The synthesis process is simple, synthesis conditions are mild, post-treatment is relatively simple, and industrial production is easy; the universality is good, and substrates with different functional groups are compatible; the yield is considerable, part of compounds are almost quantitatively converted, and the requirement of atom economy is met.
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Paragraph 0041; 0046-0047; 0050

(2021/08/07)

Preparation method of mirabegron
The invention discloses a preparation method of mirabegron, and the method comprises: S1, carrying out reduction reaction on p-nitrophenylacetonitrile to obtain p-nitrophenylacetaldehyde; S2, carryingout condensation reduction on the p-nitrophenylacetaldehyde and (R) 2-amino-1-phenethyl alcohol to obtain (R) 2-(4-nitrophenethyl) amino)-1-phenyl ethyl alcohol; S3, carrying out reduction on the (R)2-amino-1-phenethyl alcohol to obtain (R) 2-(4-nitrophenethyl) amino)-1-phenyl ethyl alcohol to obtain an intermediate (R) 2-((4-aminophenyl ethyl) amino)-1-phenyl ethyl alcohol; and S4, carrying outcondensation on the (R) 2-((4-aminophenyl ethyl) amino)-1-phenyl ethyl alcohol and aminothiazole acetic acid to obtain the mirabegron. According to the method, the starting raw materials are cheap and easy to obtain, the reaction conditions are controllable, the synthetic route steps are few, the yield is high, the cost is low, and the prepared mirabegron is high in purity.
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Page/Page column 5-8

(2019/04/30)

Copper-Catalyzed Ring-Opening/Reconstruction of Anthranils with Oxo-Compounds: Synthesis of Quinoline Derivatives
A copper-catalyzed protocol for the construction of various 2-aryl(alkyl)-3-acylquinolines or 3-arylquinolines using readily available anthranils and 1,3-diketones or aldehydes as starting materials is reported herein. Dioxygen as the sole oxidant and hexafluoroisopropanol as the solvent play an important role in both procedures. This ring-opening/reconstruction strategy involving N-O bond cleavage and C-N/C-C bond formation features high yields and broad substrate scope.
Zou, Liang-Hua,Zhu, Hao,Zhu, Shuai,Shi, Kai,Yan, Cheng,Li, Ping-Gui
p. 12301 - 12313
(2019/10/11)

Facile Access to Challenging ortho-Terphenyls via Merging Two Multi-Step Domino Reactions in One-Pot: A Joint Experimental/Theoretical Study
ortho-Terphenyls are of high interest for medicinal chemistry and materials science, but they are difficult to access. Herein, we demonstrate a straightforward and sustainable synthesis of highly functionalized ortho-terphenyls via joining an organocatalyzed two-step domino reaction (Knoevenagel/vinylogous Michael) with a DABCO/CuBr2 co-catalyzed three-step domino reaction (cyclization/tautomerization/aromatization) in a one-pot process. Overcoming necessity to isolate intermediate products leads to a reduction of energy, costs and waste for a broad scope of reactions. DFT calculations have been performed to investigate the thermodynamics of this one-pot process towards ortho-terphenyls and to study the reaction profile of the vinylogous Michael reaction under inclusion of solvent effects. Role of London dispersion forces in this transformation has been elucidated. It is shown that reaction kinetics and thermodynamics are slightly influenced by dispersion interactions. Furthermore, the addition of dispersion energy donors leads to small changes of reaction energies in some cases.
Grau, Benedikt W.,B?nisch, Simon,Neuhauser, Alexander,Hampel, Frank,G?rling, Andreas,Tsogoeva, Svetlana B.
p. 3982 - 3992
(2019/08/08)

Tetradentate amido azo Schiff base Cu(II), Ni(II) and Pd(II) complexes: Synthesis, characterization, spectral properties, and applications to catalysis in C–C coupling and oxidation reaction
New Schiff base ligands (H2L1 & H2L2) were synthesized by the reaction of salicylaldehyde with (2-((2-aminophenyl)diazenyl)-N-alkylaniline), and were used for the preparation of complexes with Cu(II), Ni(II) and Pd(II) metal ions. The structural features of the synthesized compounds were examined by UV–Vis, IR and 1H NMR spectroscopy. The crystal structures of Schiff base (H2L1) and two metal complexes Cu(L1) and Ni(L2) were determined by single crystal X-ray diffraction. The studies revealed that the synthesized Schiff bases existed as tetradentate (N,N,N,O) ligands and bonded to the metal ions through the donor atoms of the amido nitrogen, azo nitrogen, azomethine nitrogen and phenolic oxygen atoms. The redox property of Cu(L1) and Ni(L1) and emission behavior of ligand H2L1 and complexes Cu(L1) and Ni(L1) were examined. The complex Cu(L1) shows excellent catalytic activity towards oxidation of benzyl alcohol to benzyldehyde (under solvent-free condition) using H2O2 as the oxidant. Complex Pd(L1) acts as highly efficient catalyst in the Suzuki–Miyaura cross-coupling reaction of various aryl halides with phenyl boronic acid to produce the corresponding biaryls with high yields under mild reaction conditions. Both the catalysts Cu(L1) and Pd(L1) were easily recovered by simple chromatographic separation and reused for next catalytic cycle.
Pratihar, Jahar Lal,Mandal, Paritosh,Lai, Chung Kung,Chattopadhyay, Surajit
p. 317 - 324
(2019/02/06)

Synthesis of Substrates for Aldolase-Catalysed Reactions: A Comparison of Methods for the Synthesis of Substituted Phenylacetaldehydes
Methods for the synthesis of phenylacetaldehydes (oxidation, one-carbon chain extension) were compared by using the synthesis of 4-methoxyphenylacetaldehyde as a model example. Oxidations of 4-methoxyphenylethanol with activated DMSO (Swern oxidation) or manganese dioxide gave unsatisfactory results; whereas oxidation with 2-iodoxybenzoic acid (IBX) produced 4-methoxyphenylacetaldehyde in reasonable (75%) yield. However, Wittig-type one-carbon chain extension with methoxymethylene-triphenylphosphine followed by hydrolysis gave an excellent (81% overall) yield of 4-methoxyphenylacetaldehyde from 4-methoxybenzaldehyde (a cheap starting material). This approach was subsequently used to synthesise a set of 10 substituted phenylacetaldehydes in good to excellent yields.
Al-Smadi, Derar,Enugala, Thilak Reddy,Norberg, Thomas,Kihlberg, Jan,Widersten, Mikael
supporting information
p. 1187 - 1190
(2018/03/26)

Berberine derivative and use thereof
The invention discloses a berberine derivative for treating bacterium infection, and a use for thereof. The berberine derivative has a structure shown in the description. Experiments prove that the berberine derivative has positive ion charges under physiological conditions, and has the characteristics of broad antibacterial spectrum, good biocompatibility, good water solubility, strong targetingand low toxicity, a preparation method has the advantages of simplicity, easiness in implementing, high yield, and significant curative effect in the antibacterial field.
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Paragraph 0048; 0098-0099

(2018/06/15)

Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron donor in the triplet excited state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. A two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive, and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
De Souza, Aline A. N.,Silva, Nathalia S.,Müller, Andressa V.,Polo, André S.,Brocksom, Timothy J.,De Oliveira, Kleber T.
p. 15077 - 15086
(2019/01/03)

HETEROCYCLIC COMPOUND
The present invention provides a heterocyclic compound having a CDK8 and/or CDK19 inhibitory effect. The present invention provides a compound represented by formula (I) (in the formula, the symbols are as defined in the description) or a salt thereof.
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Paragraph 0564; 0671; 0672

(2017/04/11)

Heterocyclic compound
本發明提供一種具有CDK8/19抑制活性之雜環化合物。本發明提供一種如下式代表之化合物(其中各代號均如本文之定義)或其鹽。 The present invention provides a heterocyclic compound possessing CDK8/19 inhibitory activity. The present invention provides a compound represented by the formula wherein each symbol is as defined herein, or a salt thereof.
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Paragraph 0185

(2017/09/28)

Reductive activation of O2 by a bioinspired Fe complex for catalytic epoxidation reactions
Aerobic epoxidation of olefins catalyzed by iron complexes without the use of a sacrificial coreductant is unknown. We report the reductive activation of O2 by a bioinspired [(bTAML)FeIII(H2O)]- (1) complex to catalyze the epoxidation of alkenes with TONs of up to 80. Spectroscopic and kinetic evidence indicates the involvement of FeV(O) as the active oxidant during the reaction.
Singh, Kundan K.,Gupta, Sayam Sen
supporting information
p. 5914 - 5917
(2017/07/11)

Synthesis of a novel six membered CNS palladacycle; TD-DFT study and catalytic activity towards microwave-assisted selective oxidation of terminal olefin to aldehyde
This article documented synthesis of a Schiff base, E-2-(benzylthio)-N-{(2-methoxynaphthalene-1-yl)methylene}benzenamine (HL) by the treatment of 2-meyhoxynaphthaldehyde and 2-(benzylthio)aniline. Reaction of this synthesized Schiff base with Na2PdCl4has been investigated, which gave a novel six membered Pd(II) complex (PdLCl) through C,N,S-donor atom of Schiff base. These two newly synthesized compounds were characterized by1H NMR, FTIR and UV–Vis spectra and structure of the Pd(II) complex was confirmed by X-ray crystallography. The catalyst (PdLCl) displayed considerable reactivity (up to 99% selectivity and 90% yield) in the selective oxidation of terminal [Formula presented] bond in aryl substituted olefin to aldehyde. The method shows good functional groups compatibility, no ketone byproducts and is operationally simple. Time dependent density functional study (TD-DFT) of representative cyclopalladated complex has been undertaken. The simulated optical spectrum of the complex is in good agreement with the experimentally observed spectrum.
Sarma, Kuladip,Devi, Namita,Sutradhar, Dipankar,Sarma, Bipul,Chandra, Asit K.,Barman, Pranjit
p. 20 - 28
(2016/08/24)

Homogeneous catalytic oxidation of styrene and styrene derivatives with hydrogen peroxide in the presence of transition metal-substituted polyoxotungstates
The tetrabutylammonium (TBA) salts of the Keggin-type polyoxotungstates with general formula [XW11M(H2O)O39](n-m)-, where X = P, B or Si and M = Mn, Fe or Co, were evaluated as catalysts in the oxidation of styrene, α-methylstyrene, p-methylstyrene, α,p-dimethylstyrene, p-chlorostyrene, p-nitrostyrene, and p-methoxystyrene under mild conditions, using aqueous H2O2 as an eco-sustainable oxidant. In this study, the influence of the catalysts and of the different styrene substituents on the oxidation reaction profile was evaluated in terms of conversion and selectivity. For all the performed catalytic studies, the main product results from the oxidative cleavage of the vinyl double bond, except in the case of the oxidation of p-methoxystyrene catalysed by BW11Mn, for which p-methoxyphenol is the main product. The catalysts BW11Mn and SiW11Co give rise to 100% conversion for almost all of the substrates, excluding p-methoxystyrene and p-nitrostyrene for both catalysts and α,p-dimethylstyrene only in the case of BW11Mn. The selectivity for C=C cleavage products resulting from the oxidative cleavage of the vinyl double bond can be as high as 98%, reaching 98% conversion for p-nitrostyrene when SiW11Co was used as a catalyst. Possible pathways are discussed and the oxidation of a few presumed intermediates was carried out. The systematic study of several substituted styrene derivatives suggests a possible reactivity order for these compounds in the catalytic system considered.
Duarte, Tiago A. G.,Estrada, Ana C.,Simes, Mrio M. Q.,Santos, Isabel C. M. S.,Cavaleiro, Ana M. V.,Neves, M. Graca P. M. S.,Cavaleiro, Jos A. S.
p. 351 - 363
(2015/02/18)

Visible-light-mediated α-arylation of enol acetates using aryl diazonium salts
Visible light mediates efficiently the α-arylation of enol acetates by aryl diazonium salts under mild conditions using [Ru(bpy)3]Cl 2 as a photoredox catalyst. The broad scope of the reaction toward various diazonium salts and enol acetates was explored. The application of this reaction in the concise synthesis of 2-substituted indoles was demonstrated
Hering, Thea,Hari, Durga Prasad,Koenig, Burkhard
p. 10347 - 10352
(2013/01/15)

Microwave-assisted synthesis of 5-substituted 2-aminothiophenes starting from arylacetaldehydes
An easy three-step pathway for the synthesis of arylacet-aldehydes from the corresponding carboxylic acids in very high yields is described. Their use as precursors of 5-substituted-2-aminothiophenes is illustrated via a microwave-assisted Gewald reaction. This method allows obtaining the expected compounds in a shorter time and with better yields and purities than the classical procedures. Georg Thieme Verlag Stuttgart - New York.
Revelant, Germain,Dunand, Sandrine,Hesse, Stephanie,Kirsch, Gilbert
experimental part
p. 2935 - 2940
(2011/11/01)

Facile, environmentally friendly synthesis of benzaldehyde and phenylacetaldehyde analogs from readily available toluene derivatives
A facile environmentally friendly synthesis of bezaldehyde and phenylacetaldehyde analogs from readily available toluene derivatives is described. Oxidation of the styrylamines by H2O2 H2O2 affords benzaldehydes in moderate yields, while the hydrolysis of styrylamines afforded phenylacetaldehyde analogs in good yields. Copyright
Dai, Liyan,Yu, Jie,Chen, Yingqi,Yu, Shichao
p. 3078 - 3084
(2011/09/14)

Synthesis, larvicidal activity, and SAR studies of new benzoylphenylureas containing oxime ether and oxime ester group
A series of new structural benzoylphenylureas (BPUs) containing oxime ether and oxime ester group were designed and synthesized. The larvicidal activities against Oriental armyworm and mosquito of these benzoylphenylureas were evaluated and the result of bioassay displayed specific structure-activity relationship (SAR). Most of the compounds exhibited excellent larvicidal activities against Oriental armyworm and mosquito. Interestingly, some compounds showed different structure-activity relationship towards diamondback moth, beet armyworm, and corn borer although three tested insects all belong to the same insect order.
Sun, Ranfeng,Li, Yongqiang,Lue, Maoyun,Xiong, Lixia,Wang, Qingmin
supporting information; experimental part
p. 4693 - 4699
(2010/10/02)

Kinetics and mechanism of oxidation of chalcones by trichloroisocyanuric acid [TCICA] in HOAc-HCIO4 medium
The kinetics and mechanism of oxidation of chalcone and some substituted chalcones by trichloroisocyanuric acid (TCICA) has been investigated at 313 K in HOAc-HCIO4 medium. The reaction has been found to be first order each in [TCICA] and [Chalcone] and fractional order in [H+]. There is no kinetic or spectral evidence for the formation of complex between TCICA and Chalcone. The rate increases with increase in percentage of acetic acid and [CF]. The products of oxidation have been identified as phenyl acetaldehyde and benzoic acid. The reactive species of oxidant have been established as HOCl and H2OCI+. The rate increases with electron releasing groups in the benzaldehyde moety and vice versa with a Hammett's p value of -0.45. A suitable mechanism involving the chalcone molecule and the reactive species of TCICA in the rate determining step has also been proposed.
Kumar, J. Anil,Sondu
p. 1792 - 1795
(2008/03/15)

Facile solid-phase synthesis of aliphatic aldehydes using novel polymer-supported phenylselenomethyltrimethylsilane
Treatment of a novel polymer-supported phenylselenomethyltrimethylsilane reagent with LDA followed by alkylation and oxidative deselenation efficiently afforded aliphatic aldehydes in moderate to good yields with excellent purities. Copyright Taylor & Francis Group, LLC.
Sheng, Shou-Ri,Wang, Qiu-Ying,Huang, Yi-Xiang,Xin, Qin,Liu, Xiao-Ling
p. 429 - 434
(2007/10/03)

Diazo reactions with unsaturated compounds: VII. Vinyl p-methylphenyl and vinyl p-nitrophenyl ethers in the Meerwein reaction
Vinyl p-methylphenyl ether in aqueous acetone at pH 3-4 in the presence of catalytic amounts of copper(II) chloride reacts with arenediazonium chlorides to form arylacetaldehydes. Vinyl p-nitrophenyl ether under the same conditions fails to react with are
Naidan,Fesak
p. 1419 - 1420
(2007/10/03)

Reactions of aldehydes with polymer-supported selenoalkylidenetriphenylphosphoranes. A facile method for the synthesis of carbonyl compounds
The transylidation reactions of polymer-bound selenium bromide with alkylidenetriphenylphosphoranes 1 gave resin 2, which is sufficiently reactive to undergo Wittig-type reactions to afford the vinylic selenide resins 3. Cleavage gave ketones and aldehydes under different conditions.
Huang, Xian,Sheng, Shou-Ri
p. 9035 - 9037
(2007/10/03)

Nitric acid in dichloromethane solution. Facile preparation from potassium nitrate and sulfuric acid
Pure dry HNO3 can be liberated from KNO3 with 96% H2SO4 directly into CH2Cl2 to yield solutions of variable concentration for use in a number of organic reactions. The present method efficiently replaces the employment of 100% HNO3 in some synthetic applications, avoiding the problems associated in storage and handling the acid.
Strazzolini, Paolo,Giumanini, Angelo G.,Runcio, Antonio
p. 1387 - 1389
(2007/10/03)

Mechanistic studies of the oxidation of substituted phenethyl alcohols by N-metallo-N-haloarylsulphonamides: Kinetic isotope studies
The oxidation of para-substituted phenethyl alcohols (PEA, 2) by N-metallo-N-haloarylsulphonamides (1) in the presence of dilute HCl to the corresponding phenacetaldehydes (4) is first order with respect to oxidant (1) and [H+] and a fract ional order each in [PEA] and [Cl-]. Addition of the reaction product (3), ionic strength variations and variation of dielectric constant of the medium had no effect on the rate. The oxidation of PhCH2CD2OH (2) exhibited a substantial primary kinetic isotope effect (kH/kD=5.83). The rates correlate satisfactorily with the Hammett free energy relationship. The activation parameters ΔH≠, ΔS≠, ΔG≠ and logA were calculated for the i reaction. The proposed mechanism is consistent with the observed results. Copyright
Rangappa, Kanchugarakoppal S.
p. 684 - 690
(2007/10/03)

4-Aminopiperidine ureas as potent selective agonists of the human β3-Adrenergic receptor
The preparation and structure-activity relationships (SARs) of potent agonists of the human β3-adrenergic receptor (AR) derived from a 4-aminopiperidine scaffold are described. Examples combine human β3-AR potency with selectivity over human β1-AR and/or human β2-AR agonism. Compound 29s was identified as a potent (EC50 = 1 nM) and selective (greater than 400-fold over β1- with no β2-AR agonism) full β3-AR agonist with in vivo activity in a transgenic mouse model of thermogenesis.
Ashwell, Mark A,Solvibile Jr., William R,Han, Stella,Largis, Elwood,Mulvey, Ruth,Tillet, Jeffrey
p. 3123 - 3127
(2007/10/03)

Ferrocenyl derivatives with one, two, or three sulfur-containing arms for self-assembled monolayer formation
Self-assembled monolayers of electroactive molecules can form on gold electrodes if the molecules include a sulfur-containing group to coordinate with the gold surface. We have prepared a molecule with a tripod of sulfur groups that has the potential of fixing the geometry of the molecule relative to the gold surface. The target (3) contained the good one-electron donor ferrocene connected through a benzene spacer to an isobutane tripod, with each arm of the tripod ending in a methylthio group. Analogous compounds with one (1) and two (2) coordinating arms were also prepared.
Hu, Jian,Mattern, Daniell Lewis
p. 2277 - 2281
(2007/10/03)

Experiments on the Chaperon effect in the nitration of aromatics
A nitro group may be effectively delivered to the ortho position of alkylbenzenes, provided that a suitable chaperon function is located in α- position and a dilute of HNO3 in CH2Cl2 is used. The carbonyl function of an aldehyde or ketone is the best choice, but a carboxyl, alkoxycarbonyl, and amide groups all work well. The ether function showed a less pronounced ortho orientation effect, whereas the hydroxyl group was too prone to oxidation. Side reactions were minimal under the conditions employed. A para chaperon effect was seemingly at work in the CH2Cl2 nitration of benzenepropanenitrile. All the results were compared with the corresponding classical nitration in H2SO4.
Strazzolini, Paolo,Giumanini, Angelo G.,Runcio, Antonio,Scuccato, Massimo
p. 952 - 958
(2007/10/03)

Kinetics and Mechanism of Oxidation of Benzal Methylphenyl Sulphides by Vanadium(v)
The rates of oxidation of benzal methylphenyl sulphide (BMS) and some substituted BMS's by vanadium(v) ion were measured in aqueous acetic acid in the presence of perchloric acid. The reaction is first order in [VV] and fraction in [BMS]. The reaction is acid-catalysed. Addition of NaClO4 had no effect on the rate. The rates were also found to be sensitive to solvent polarity. Formation of an intermediate complex between VV and BMS and subsequent decomposition of this in a slow step, involving the attack of oxidant on the non-bonded electrons of sulphide sulpher is proposed as the probable mechanism.
Karunakaran, Kolandaivelu,Elango, Kuppanagounder Pitchaimuthu
p. 299 - 301
(2007/10/03)

Oxidation of substituted phenethyl alcohols by sodium N-chlorobenzenesulphonamide: A kinetic study
The kinetics of the oxidation of six substituted phenethyl alcohols by sodium N-chlorobenzenesulphonamide or chloramine-B (CAB) in the presence of HCl was studied at 35°C. The rate shows a first-order dependence on [CAB]0 and [H+] and is fractional order in [PEA]θ and [Cl-]. Ionic strength variations, addition of reaction product of benzenesulphonamide and variation of the dielectric constant of the medium have no effect on the rate. The solvent isotope effect K1H2Ok1D2O≈O.78. Proton inventory studies were made in H2O-D2O mixtures. The rates correlate satisfactorily with the Hammett linear free energy relationship. The reaction constant ρ was -3-5 for electron-releasing and -0-30 for electron-withdrawing groups at 35 °C. Activation parameters ΔH*, ΔS*, ΔG* and log A were calculated for the reaction. An isokinetic relationship is observed with β= 338 K, indicating enthalpy as a controlling factor.
Ramachandra,Rangappa,Mahadevappa
p. 439 - 446
(2007/10/03)

Oxidation of substituted phenethyl alcohols by sodium n-chlorobenzenesulphonamide: A kinetic study
The kinetics of the oxidation of six substituted phenethyl alcohols by sodium N-chlorobenzenesulphonamide or chloramine-B (CAB) in the presence of HCl was studied at 35°C. The rate shows a first order dependence on [CAB]0 and [H+] and is of fractional order in [PEA]0 and [Cl-]. Ionic strength variations, addition of the reaction product of benzenesulphonamide and variation of the dielectric constant of the medium have no effect on the rate. The solvent isotope effect kH2O1/kD2O1≈0·78. Proton inventory studies were made in H20-D20 mixtures. The rates correlate satisfactorily with Hammett's LFER. The reaction constant ρ was -3·5 for electron-releasing substituants and -0·30 for electron withdrawing groups at 35°C. Activation parameters ΔH?, ΔS?, ΔG? and log A were computed for the reaction. An isokinetic relationship is observed with β = 338 K, indicating enthalpy as a controlling factor.
Ramachandra,Rangappa,Mahadevappa
p. 279 - 286
(2007/10/03)

Oxidation of Substituted Phenethyl Alcohols by Sodium-N-chloro-p-toluene sulfonamide: A Kinetic Study
The kinetics of the oxidation of six p-substituted phenethyl alcohols (PEA, R = H, -Cl, -Br, -CH3, -OCH3, and -NO2) by sodium-N-chloro-p-toluene sulfonamide (chloramine-T, CAT) in the presence of HCl was studied at 35 °C. The rate shows a first order dependence on [CAT]0 and [H+]0 and a fractional order in [PEA]0 and [Cr-]0. Ionic strength variations, addition of reaction product toluene sulfonamide, and variation of the dielectric constant of the medium have no effect on the rate. The solvent isotope effect k′H2O/k′D2O amounts to about 0.90. Proton inventory studies have been made in H2O-D2O mixtures. The rates correlate satisfactorily with Hammett's relationship. The reaction constant ρ was -3.3 for electron releasing substituents and -0.25 for electron withdrawing groups at 35 °C. The activation parameters ΔH#, ΔS#, ΔG#, and logA were derived. ΔH# and ΔS# are linearly related, and an isokinetic relationship is observed with β = 166.7 K, indicating entropy as a controlling factor.
Ramachandra,Rangappa,Mahadevappa,MadeGowda
p. 241 - 255
(2007/10/03)

Kinetics and mechanism of oxidation of phenethyl alcohols by bromamine-T in acid medium
The kinetics of the oxidation of six substituted phenethyl alcohols (X-C6H4-CH2-CH2-OH where X=-H, -Cl, -Br, -CH3, -OCH3 and -NO2) by sodium N-bromo-p-toluenesulphonamide or bromamine-T (BAT) in the presence of HCl has been studied at 35°C. The reaction rate shows a first order dependence both on the [BAT]0 and the [H+] and is fractional order with respect to [PEA]0 and [Cl-]. The change in the ionic strength and dielectric constant of the medium and the addition of reaction product, p-toluenesulphonamide have no effect on the reaction rate. The solvent isotope effect k1(H2O)/k1(D2O) ?0.86. Proton inventory studies have been made in H2O-D2O mixtures. The rates satisfactorily correlate with Hammett's LFER. The reaction constant ρ has been found to be -3.1 for electron releasing substituents and -0.26 for electron withdrawing groups at 35°C. Activation parameters ΔH≠, ΔS≠, ΔG≠ and logA are calculated by studying the reaction at different temperatures (308-318K). It is seen that ΔH≠ and ΔS≠ are linearly related and an isokinetic relationship is observed with β = 330K, indicating enthalpy to be a controlling factor.
Ramachandra,Rangappa,Mahadevappa
p. 703 - 707
(2007/10/03)

A novel synthesis of vinyl dithiocarbamates via phosphonium ylides
In the presence of potassium carbonate, N, N-dimethylamino thiocarbonyl thiomethyl triphenylphosphonium bromide can form the corresponding ylide in situ, which can undergo Wittig reaction with aldehydes to give vinyl dithiocarbamates in high yields. If th
Huang, Zhi-Zhen,Wu, Lu Ling
p. 509 - 514
(2007/10/03)

Effects of Para-Substituents on the Mechanisms of Solvolysis of Styrene Oxides
Rate and product studies of the hydronium ion-catalyzed, hydroxide ion-catalyzed, and spontaneous reactions of styrene oxide and its p-CH3O, p-CH3, p-Cl, and p-O2N-derivatives in water solutions have been carried out.A Hammett correlation of log k for the acid-catalyzed reactions vs ?+ gives a slope ρ+ of -4.2 and only diol products are formed.An intermediate in the hydronium ion-catalyzed hydrolysis of p-methoxystyrene oxide is trapped, subsequent to its rate-limiting formation, by azide ion.The spontaneous reactions of p-methylstyrene oxide and styrene oxide yield only diol products, and their reactions in 18O-water indicate that >/= 98percent and ca. 95percent, respectively, of 18O is incorporated into the benzyl positions.Nucleophilic addition of water to the benzyl carbon of neutral epoxide is proposed as the mechanism of the primary component of the spontaneous reaction for the p-CH3-, p-H- and p-Cl-substrates on the basis of a Hammett ρ of -2.0.The spontaneous rate constant for reaction of p-methoxystyrene oxide is much greater than that expected from a Hammett correlation for the p-CH3, p-H-, and p-Cl-styrene oxides.This increased rate is attributed to the incursion of a reaction that yields mainly (>80percent) p-methoxyphenylacetaldehyde.The regiochemistries of addition of hydroxide ion in 18O-water to p-CH3-, p-H-, and p-Cl-, and p-O2N-substituted styrene oxides were also determined and found to vary as functions of the para substituent.Addition of hydroxide and methoxide ions to the α-carbon is favored by electron-donating groups in the phenyl ring, and addition of these nucleophiles to the β-carbon is favored by electron-withdrawing groups in the phenyl ring.
Blumenstein, Jeffrey J.,Ukachukwu, Victoria C.,Mohan, Ram S.,Whalen, Dale L.
p. 924 - 932
(2007/10/02)

Antibody bait and switch catalysis: A survey of antigens capable of inducing abzymes with acyl-transfer properties
Antibodies have been shown to catalyze acyl-transfer reactions. Various antigens have been applied to these hydrdytic reactions, but typically all encompass the same theme of incorporating a monoanionic phosphonate/phosphonamidatc. To expand the scope and
Janda, Kim D.,Weinbouse, Michael I.,Danon, Tami,Pacelli, Karen A.,Schloeder, Diane M.
p. 5427 - 5434
(2007/10/02)

REARRANGEMENT OF ARYL-SUBSTITUTED EPOXIDES IN THE PRESENCE OF NaBH4
Aromatic epoxides are rearranged to the corresponding aldehydes when NaBH4 is used as reducing agent in benzene at 45 deg C.If the solvents are THF, EtOH ot i-PrOH, the main products of the ring-opening reaction by NaBH4 are the secondary alcohols.
Shaozu, Wu,Yulan, Zhang,Huidong, Wang
p. 519 - 520
(2007/10/02)

Catalytic Asymmetric Epoxidations with Chiral Iron Porphyrins
Iron porphyrins have been modified to include optically active functionalities at the meso positions.Asymmetric epoxidations of prochiral olefins with these chiral iron porphyrins and iodosyl compounds have been investigated.Thus, 5α,10β,15α,20β-tetrakis(o-(R)-hydratropamidophenyl)porphyrin (H2T(α,β,α,β-Hyd)PP) and 5α,10β,15α,20β-tetrakis(ophenyl)porphyrin (H2T(α,β,α,β-Binap)PP) were synthesized by the condensation of optically active acid chlorides with 5α,10β,15α,20β-tetrakis(o-aminophenyl)porphyrin.Subsequent insertion of iron into H2T(α,β,α,β-Hyd)PP and H2T(α,β,α,β-Binap)PP gave FeT(α,β,α,β-Hyd)PPCl and FeT(α,β,α,β-Binap)PPCl, respectively.Emploing FeT(α,β,α,β-Hyd)PPCl iodosylbenzene, styrene was oxidized to (R)-(+)-styrene oxide in 31percent ee.Similarly, FeT(α,β,α,β-Binap)PPCl and iodosylmesitylene gave (R)-(+)-styrene oxide in 48percent ee.Various substituted styrenes and aliphatic olefins were epoxidized with enantiomeric excesses varying between 0percent for 1-methylcyclohexene oxide and 51percent for p-chlorostyrene oxide.
Groves, John T.,Myers, Richard S.
p. 5791 - 5796
(2007/10/02)

Photohydration of Aromatic Alkenes and Alkynes
The photohydrations of aromatic alkenes and alkynes 2-12 have been studied in aqueous sulfuric acid.For the nonnitro-substituted substrates 2-8, the products are the compounds obtained via Markovnikov addition of water to the alkene or alkyne moiety.Nitro-substituted styrenes 11 and 12 and phenylacetylenes 9 and 10 gave anti-Markovnikov addition products.Product quantum yields (Ψpdt) generally show a strongly sigmoidal dependence on the activity of the medium, with the exception of the nitrostyrenes, where no such dependence was observed.For compounds 2-8, quenching of fluorescence with increasing acidity was observed, and the proposed photohydration mechanism involves a rate-limiting protonation step on the first excited singlet state (S1), while for the nitrostyrenes, a rate-limiting attack of water on T1 is consistent with the available data.A mechanism involving a concerted addition of H3O+ to T1 is proposed for the photohydration of (nitrophenyl)acetylenes 9 and 10.The solvent isotope effect on the product quantum yield (ΨH/ΨD) is consistent with these proposals.Photoprotonation rate constants (kH) have been obtained - via transient and steady state measurements - for substrates 2, 4-6, and 8.Alkenes are approximately ane order of magnitude less reactive than alkynes to photoprotonation, both of which are 1011 - 1014 times more reactive than the corresponding ground-state molecules.
Wan, Peter,Culshaw, Stephen,Yates, Keith
p. 2509 - 2515
(2007/10/02)

Reaction of Phenyl Styryl Ketone and Its Substituted Analogues with Ce(IV) in H2SO4-HOAc Mixtures: A Kinetic Study
Kinetics of oxidation of chalcone (phenyl styryl ketone) and its substituted analogues by Ce(IV) in H2SO4-HOAc mixtures has been investigated in the temperature range 40 deg-60 deg C.The rate law is found to be -d/dt = k''.The rate increases with the increase in at constant ionic strength, but decreases with increase in and percentage of acetic acid at constant .The effect of various substituents in the phenyl ring, directly attached to the double bond, on rate is in the order: p-Me > m-Me > p-Cl > H > m-Cl > m-NO2 >p-NO2.A mechanism in which the cleavage of carbon-carbon single bond, forming styryl carbonium ion and benzoyl radical, occurs in the rate-determining step is proposed.Activation parameters are also presented and discussed.
Sondu, S.,Sethuram, B.,Rao, T. Navaneeth
p. 883 - 885
(2007/10/02)