- A novel one pot synthesis of o-nitrophenylacetic acid and unexpected p-nitrobenzoic acid by HNO3-mediated CH2 extrusion reaction of phenylacetic acid
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The HNO3-mediated CH2 extrusion reactions of phenylacetic acid lead to one pot synthesis of unexpected commercially important product 4-nitrobenzoic acid through the formation of 4-nitrophenylacetic acid and 2-nitrophenylacetic acid. Copyright
- Sohail, Muhammad,Raza, Abdul Rauf
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- The electrochemical behavior of 4-nitrobenzyl bromide and its catalytic activity for reduction of CO2 in the acetonitrile solvent at the Cu/Pd/rGO/GCE surface
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In this study, 4-nitrobenzyl bromide was used as a catalyst for reduction of CO2 and as an initial substrate for electrosynthesis of 4-nitrophenylacetic acid. Cu nanoparticles/Pd nanoparticles/reduced graphene oxide nanocomposite modified glassy carbon electrode (Cu/Pd/rGO/GCE) was used to promote electroactivation of CO2. rGO film was fabricated via electrochemical reduction of dispersed GO nanosheets on the GCE surface. Cyclic voltammetry procedure was applied in two steps to deposit Pd and Cu nanoparticles on the rGO/GCE surface. The morphology and structure of the nanocomposites were characterized using FESEM, EDS, AFM and XRD analysis. FTIR, 1H and 13C NMR spectral characteristics were used to identify the final products of the catalytic process. The electrocarboxylation of 4-nitrobenzyl bromide occurs at a potential which is less negative than those reported for other aryl halides. The results indicate that 4-nitrobenzyl bromide, as a catalyst, plays a dual role in the electrosynthesis of 4-nitrophenylacetate. The dual role includes the electrocatalytic reduction of CO2 and reaction of produced CO2 ?? with 4-nitrobenzyl bromide radical anion. Finally, an EC'C mechanism is proposed for the electrosynthesis of 4-nitrophenylacetate.
- Benvidi, Ali,Ghobadi, Kobra,Khoshro, Hossein,Mohammadzadeh, Safoora,Zare, Hamid R.
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- Novel carbazole-stilbene hybrids as multifunctional anti-Alzheimer agents
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Molecules capable of engaging with multiple targets associated with pathological condition of Alzheimer's disease have proved to be potential anti-Alzheimer's agents. In our goal to develop multitarget-directed ligands for the treatment of Alzheimer's disease, a novel series of carbazole-based stilbene derivatives were designed by the fusion of carbazole ring with stilbene scaffold. The designed compounds were synthesized and evaluated for their anti-AD activities including cholinesterase inhibition, Aβ aggregation inhibition, antioxidant and metal chelation properties. Amongst them, (E)-1-(4-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)phenyl)-3-(2-(pyrrolidin-1-yl)ethyl)thiourea (50) appeared to be the best candidate with good inhibitory activities against AChE (IC50 value of 2.64 μM) and BuChE (IC50 value of 1.29 μM), and significant inhibition of self-mediated Aβ1–42 aggregation (51.29% at 25 μM concentration). The metal chelation study showed that compound (50) possessed specific copper ion chelating property. Additionally, compound (50) exhibited moderate antioxidant activity. To understand the binding mode of 50, molecular docking studies were performed, and the results indicated strong non-covalent interactions of 50 with the enzymes in the active sites of AChE, BuChE as well as of the Aβ1-42 peptide. Additionally, it showed promising in silico ADMET properties. Putting together, these findings evidently showed compound (50) as a potential multitarget-directed ligand in the course of developing novel anti-AD drugs.
- Chaudhary, Bharat N.,Gandhi, Pallav M.,Joshi, Prashant D.,Kanhed, Ashish M.,Patel, Dushyant V.,Patel, Kirti V.,Patel, Kishan B.,Patel, Nirav R.,Patel, Sagar P.,Prajapati, Navnit K.,Teli, Divya M.,Yadav, Mange Ram
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- Substituted 9-Diethylaminobenzo[ a]phenoxazin-5-ones (Nile Red Analogues): Synthesis and Photophysical Properties
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Nile Red is a benzo[a]phenoxazone dye containing a diethylamino substituent at the 9-position. In recent years, it has become a popular histological stain for cellular membranes and lipid droplets due to its unrivaled fluorescent properties in lipophilic environments. This makes it an attractive lead for chemical decoration to tweak its attributes and optimize it for more specialized microscopy techniques, e.g., fluorescence lifetime imaging or two-photon excited fluorescence microscopy, to which Nile Red has never been optimized. Herein, we present synthesis approaches to a series of monosubstituted Nile Red derivatives (9-diethylbenzo[a]phenoxazin-5-ones) starting from 1-naphthols or 1,3-naphthalenediols. The solvatochromic responsiveness of these fluorophores is reported with focus on how the substituents affect the absorption and emission spectra, luminosity, fluorescence lifetimes, and two-photon absorptivity. Several of the analogues emerge as strong candidates for reporting the polarity of their local environment. Specifically, the one- and two-photon excited fluorescence of Nile Red turns out to be very responsive to substitution, and the spectroscopic features can be finely tuned by judiciously introducing substituents of distinct electronic character at specific positions. This new toolkit of 9-diethylbenzo[a]phenoxazine-5-ones constitutes a step toward the next generation of optical molecular probes for advancing the understanding of lipid structures and cellular processes.
- Hornum, Mick,Mulberg, Mads W.,Szomek, Maria,Reinholdt, Peter,Brewer, Jonathan R.,Wüstner, Daniel,Kongsted, Jacob,Nielsen, Poul
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- Synthesis, optical and nonlinear optical properties of new pyrazoline derivatives
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We report on synthesis and optical properties of new organic compounds based on substituted pyrazole ring. The investigated pyrazoline derivatives (PRDs) exhibit efficient broadband photoluminescence which covers nearly whole visible spectrum. The experimental results are compared to quantum chemical calculations. Amplified spontaneous emission and photodegradation measurements were performed for hybrid systems based on selected PRDs doped into poly(methyl methacrylate) matrix proving the potential utility of such systems in lasing applications. Two-photon absorption (TPA) properties were characterized by the femtosecond Z-scan technique.
- Mysliwiec,Szukalski,Sznitko,Miniewicz,Haupa,Zygadlo,Matczyszyn,Olesiak-Banska,Samoc
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- Regio- and chemoselective enzymatic N-oxygenation in vivo, in vitro, and in flow
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(Chemical Equation Presented) Action by the para: Evaluation of the nitro-group-forming N-oxygenase AurF in vivo, in vitro, and immobilized as a fusion protein with simply H2O2 as oxidant (peroxide shunt) reveals para-regioselective oxygenation of aromatic amines (see scheme). This effect includes the selective oxygenation of diamino compounds.
- Winkler, Robert,Richter, Martin E. A.,Knuepfer, Uwe,Merten, Dirk,Hertweck, Christian
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- Design, synthesis and biological evaluation of novel sesquiterpene mustards as potential anticancer agents
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Several novel series of sesquiterpene mustards (SMs) bearing nitrogen mustard and glutathione (GSH)-reactive α-methylene-γ-butyrolactone groups were successfully prepared for the first time and showed excellent antiproliferative activities in vitro. Among them, compounds 2e and 2g displayed the highest antiproliferative properties with IC50 values ranging from 2.5 to 8.7 μM. The selectivity of these two compounds was evaluated by SRB method against human cancer and normal hepatic cells (HepG2 and L02). The induction of apoptosis and effects on the cell cycle distribution with compounds 2e and 2g were investigated by Hoechst 33,258 staining and flow cytometry, which exhibited that they could induce selective cell apoptosis and cell cycle arrest in HepG2 and L02 cells. In addition, further investigation showed that compounds 2e and 2g could obviously inhibit the proliferation of HepG2 cells by inducing significant DNA cross-linking and depleting GSH in cell media. The good cytotoxicity and selectivity of compounds 2e and 2g pointed them as promising leads for anticancer drug design.
- Xu, Yuan-Zhen,Gu, Xue-Yan,Peng, Shou-Jiao,Fang, Jian-Guo,Zhang, Ying-Mei,Huang, De-Jun,Chen, Jian-Jun,Gao, Kun
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- Pd(OH)2/C, a Practical and Efficient Catalyst for the Carboxylation of Benzylic Bromides with Carbon Monoxide
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A simple, efficient, cheap, and broadly applicable system for the carboxylation of benzylic bromides with carbon monoxide and water is reported. Upon simple reaction with only 2.5 wt % of Pearlman's catalyst and 10 mol % of tetrabutylammonium bromide in tetrahydrofuran at 110 °C for 4 h, a range of benzylic bromides can be smoothly converted to the corresponding arylacetic acids in good to excellent yields after simple extraction and acid-base wash. The reaction was found to be broadly applicable, scalable, and could be successfully extended to the use of ex situ-generated carbon monoxide and applied to the synthesis of the nonsteroidal anti-inflammatory drug diclofenac.
- Wakuluk-Machado, Anne-Marie,Dewez, Damien F.,Baguia, Hajar,Imbratta, Miguel,Echeverria, Pierre-Georges,Evano, Gwilherm
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p. 713 - 723
(2020/02/04)
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- Preparation method of phenylacetic acid type compound
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The invention discloses a preparation method of a phenylacetic acid type compound. The preparation method of the phenylacetic acid type compound I comprises the following steps that in a solvent and aCO gas phase system, a benzyl halide type compound II, pyridine-2-cobalt carboxylate, palladium acetate and alkaline neutralizers take carbonylation reaction to obtain the phenylacetic acid type compound I. A mixed catalytic system has a synergistic effect; the whole use quantity of catalysts is greatly reduced. When the mixed catalyst is used, a better catalytic effect can be achieved; the characteristics of easily obtaining the catalyst, avoiding the production safety risk of toxic three wastes and the like, reducing the reaction pressure, realizing mild reaction conditions, reducing the production risk, facilitating the production and the like are realized. The formulas are shown in description.
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Paragraph 0113; 0114; 0115
(2019/02/21)
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- Preparation method of methyl p-aminophenylacetate
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An embodiment of the invention provides a preparation method of methyl p-aminophenylacetate and relates to the field of chemical synthesis. According to the preparation method, benzyl cyanide is adopted as a starting material and subjected to nitration, hydrolysis, esterification, reduction and other steps in sequence, and methyl p-aminophenylacetate is obtained with high yield. The preparation method adopts a reasonable route, is simple to operate, does not have quite high requirement for equipment and is suitable for large-scale industrial production, and the raw material is widely sourced.
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Paragraph 0051; 0052; 0053; 0054; 0055
(2019/01/14)
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- Dynamic kinetic resolution of bis-aryl succinic anhydrides: Enantioselective synthesis of densely functionalised γ-butyrolactones
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The efficient Dynamic Kinetic Resolution (DKR) of disubstituted anhydrides has been shown to be possible for the first time. Using an ad hoc designed organocatalyst and an enantio- and diastereoselective cycloaddition process with aldehydes, stereochemically complex γ-butyrolactone derivatives can be obtained-with control over three contiguous stereocentres, one of which is all carbon quaternary.
- Claveau, Romain,Twamley, Brendan,Connon, Stephen J.
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supporting information
p. 3231 - 3234
(2018/04/05)
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- Preparation method of 4-aminophenylacetic acid medicine intermediate
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The invention provides a preparation method of a 4-aminophenylacetic acid medicine intermediate. The preparation method comprises 1, adding concentrated sulfuric acid, concentrated nitric acid and benzyl cyanide into a reactor, carrying out a reaction process, and carrying out crystallization, filtration, water washing and re-crystallization to obtain 4-nitrophenylacetonitrile, 2, adding a sulfuric acid solution and glacial acetic acid into the 4-nitrophenylacetonitrile, carrying out heating backflow, after the reaction, pouring the reaction mixture into a reactor with ice water so that the product is crystallized and precipitated in the ice water, carrying out suction filtration to obtain white solids, carrying out re-crystallization through distilled water and glacial acetic acid, and drying the crystals to obtain 4-nitrophenylacetic acid, 3, adding 4-nitrophenylacetic acid, ethanol and skeletal nickel into a pressure reactor according to a certain ratio, carrying out a reaction process for some time, carrying out standing cooling to the room temperature, distilling to remove solvent ethanol, cooling the solution for crystallization, filtering the crystals and drying the crystals to obtain crude products, and 4, carrying out re-crystallization on the crude products through ethanol, and carrying out decoloring through active carbon to obtain light white crystals of 4-aminophenylacetic acid. The preparation method has a low cost and less side reactions and is suitable for industrial application.
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Paragraph 0012
(2017/05/10)
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- Organocatalytic oxidation of substituted anilines to azoxybenzenes and nitro compounds: Mechanistic studies excluding the involvement of a dioxirane intermediate
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An organocatalytic and environmentally friendly approach for the selective oxidation of substituted anilines was developed. Utilizing a 2,2,2-trifluoroacetophenone-mediated oxidation process, substituted anilines can be transformed into azoxybenzenes, while a simple treatment with MeCN and H2O2 leads to the corresponding nitro compounds, providing user-friendly protocols that can be easily scaled up. Various substitution patterns and functional groups were tolerated leading to products in high to excellent yields. Mechanistic studies utilizing HRMS provide clear evidence for the distinct mechanistic intermediates that are involved. This study constitutes an indirect proof excluding the involvement of a dioxirane intermediate in the green organocatalytic oxidation, utilizing 2,2,2-trifluoroacetophenone as the catalyst.
- Voutyritsa, Errika,Theodorou, Alexis,Kokotou, Maroula G.,Kokotos, Christoforos G.
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supporting information
p. 1291 - 1298
(2017/06/06)
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- A high-throughput screening method for determining the substrate scope of nitrilases
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Nitrile compounds are intermediates in the synthesis of pharmaceuticals such as atorvastatin. We have developed a chromogenic reagent to screen for nitrilase activity as an alternative to Nessler's reagent. It produces a semi-quantifiable blue colour and hydrolysis of 38 nitrile substrates by 23 nitrilases as cell-free extracts has been shown. This journal is
- Black, Gary W.,Brown, Nicola L.,Perry, Justin J. B.,Randall, P. David,Turnbull, Graeme,Zhang, Meng
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supporting information
p. 2660 - 2662
(2015/03/05)
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- Meso-Methylhydroxy BODIPY: A scaffold for photo-labile protecting groups
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Here, we show that by installing a meso-methylhydroxy moiety, the boron dipyrromethene (BODIPY) scaffold can be converted into an efficient caging group, removable by green light. We describe caging and uncaging of important chemical functionalities and demonstrate green light mediated control over biological processes in cultured cell lines and neurons. This journal is
- Rubinstein, Naama,Liu, Pei,Miller, Evan W.,Weinstain, Roy
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supporting information
p. 6369 - 6372
(2015/04/14)
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- Oxidative cleavage of α-sulfonyl ketones to carboxylic acids with Ce(NH4)2(NO3)6
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Tandem oxidative cleavage of α-sulfonyl arylketones 2 with the combination of Ce(NH4)2(NO3)6 and O2 in MeCN afforded carboxylic acids 3 in moderate to good yields. The plausible reaction mechanism has
- Chang, Meng-Yang,Tsai, Chung-Yu
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supporting information
p. 5548 - 5550
(2014/12/11)
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- Structural characterization and function determination of a nonspecific carboxylate esterase from the amidohydrolase superfamily with a promiscuous ability to hydrolyze methylphosphonate esters
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The uncharacterized protein Rsp3690 from Rhodobacter sphaeroides is a member of the amidohydrolase superfamily of enzymes. In this investigation the gene for Rsp3690 was expressed in Escherichia coli and purified to homogeneity, and the three-dimensional structure was determined to a resolution of 1.8 ? The protein folds as a distorted (β/α)8-barrel, and the subunits associate as a homotetramer. The active site is localized to the C-terminal end of the β-barrel and is highlighted by the formation of a binuclear metal center with two manganese ions that are bridged by Glu-175 and hydroxide. The remaining ligands to the metal center include His-32, His-34, His-207, His-236, and Asp-302. Rsp3690 was shown to catalyze the hydrolysis of a wide variety of carboxylate esters, in addition to organophosphate and organophosphonate esters. The best carboxylate ester substrates identified for Rsp3690 included 2-naphthyl acetate (kcat/Km = 1.0 × 105 M-1 s-1), 2-naphthyl propionate (k cat/Km = 1.5 × 105 M-1 s -1), 1-naphthyl acetate (kcat/Km = 7.5 × 103 M-1 s-1), 4-methylumbelliferyl acetate (kcat/Km = 2.7 × 103 M-1 s-1), 4-nitrophenyl acetate (kcat/Km = 2.3 × 105 M-1 s-1), and 4-nitrophenyl butyrate (kcat/Km = 8.8 × 105 M -1 s-1). The best organophosphonate ester substrates included ethyl 4-nitrophenyl methylphosphonate (kcat/Km = 3.8 × 105 M-1 s-1) and isobutyl 4-nitrophenyl methylphosphonate (kcat/Km = 1.1 × 104 M-1 s-1). The (SP)-enantiomer of isobutyl 4-nitrophenyl methylphosphonate was hydrolyzed 10 times faster than the less toxic (RP)-enantiomer. The high inherent catalytic activity of Rsp3690 for the hydrolysis of the toxic enantiomer of methylphosphonate esters make this enzyme an attractive target for directed evolution investigations.
- Xiang, Dao Feng,Kumaran, Desigan,Swaminathan, Subramanyam,Raushel, Frank M.
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p. 3476 - 3485
(2014/06/23)
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- Synthesis of novel fluorescent 2-{4-[1-(pyridine-2-yl)-1H-pyrazol-3-yl] phenyl}-2H-naphtho [1,2-d] [1,2,3] triazolyl derivatives and evaluation of their thermal and photophysical properties
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Novel 2-{4-[1-(pyridine-2-yl)-1H-pyrazol-3-yl] phenyl}-2H-naphtho [1,2-d] [1,2,3] triazolyl fluorescent derivatives were synthesized from p-nitrophenylacetic acid and 2-hydrazino pyridine through Vilsmeier-Haack and diazotization reactions. Photophysical properties were evaluated, and results show that compounds have good fluorescence quantum yields. Thermal analysis showed that they are reasonably stable. The structures of the compounds were confirmed by FT-IR, 1H NMR, 13C NMR, and mass spectral and elemental analysis.
- Padalkar, Vikas S.,Phatangare, Kiran R.,Sekar
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p. 809 - 813
(2013/08/23)
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- One-pot chemoenzymatic synthesis of aldoximes from primary alcohols in water
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A new synthetic method for the one-pot preparation of aldoximes in water was developed; the method is based on the combination of the enzymatic oxidation of primary alcohols to aldehydes using different acetic acid bacteria and in situ condensation of the aldehydes with hydroxylamine.
- Zambelli, Paolo,Pinto, Andrea,Romano, Diego,Crotti, Elena,Conti, Paola,Tamborini, Lucia,Villa, Raffaella,Molinari, Francesco
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body text
p. 2158 - 2161
(2012/09/22)
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- Nitrile biotransformation by whole cells of Aspergillus sp. PTCC 5266
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Aspergillus sp. PTCC 5266 exhibited nitrile-hydrating activity over a broad pH range from 6.0 to 10.0 at 26°C. It hydrated 4-nitrophenylacetonitrile, 2-chlorobenzonitrile and 3-chlorobenzonitrile to their corresponding carboxylic acids and amides, while benzyl cyanide, benzonitrile, 4-tolunitrile, cyclohexanecarbonitrile, 4-chlorobutyronitrile and isobutyronitrile gave carboxylic acids as the sole products. The maximum whole-cell nitrile-hydrating activity was observed at pH 7.0.
- Yousefi,Mohammadi,Habibi,Cheraghi
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body text
p. 54 - 59
(2012/03/10)
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- Facile and chemoselective cleavage of allyl carboxylic ester utilizing NaBH4 in DMSO
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A new method for deprotection of allyl carboxylic ester has been observed by using the inexpensive reagent sodium borohydride in dimethyl sulfoxide (DMSO). Aliphatic and aromatic allyl carboxylic ester undergo deprotection smoothly. The allyl ester group can selectively deprotect better than phenol.
- Pawar, Bharati V.,Lokhande, Pradeep D.
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experimental part
p. 2445 - 2453
(2009/12/06)
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- Development of a one-pot method for the homologation of aldehydes to carboxylic acids
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A highly efficient method is described for the one-carbon homologation of aldehydes to carboxylic acid derivatives employing the reaction of a 1,1-bis-dimethylphosphonate derivative with the aldehyde and controlled acid hydrolysis of the derived α-phosphonoenamine intermediate.
- McNulty, James,Das, Priyabrata
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experimental part
p. 7794 - 7800
(2009/12/26)
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- General and practical conversion of aldehydes to homologated carboxylic acids
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(Chemical Equation Presented) The reaction of aldehydes with trichloromethide followed by sodium borohydride or sodium phenylseleno(triethyl) borate under basic conditions affords homologated carboxylic acids in high yields. This operationally simple procedure provides a practical, efficient alternative to other homologation protocols. The approach is compatible with sensitive aldehydes including enals and enolizable aldehydes. It also offers convenient access to α-monodeuterated carboxylic acids.
- Cafiero, Lauren R.,Snowden, Timothy S.
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supporting information; experimental part
p. 3853 - 3856
(2009/07/01)
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- An improved synthesis of α-phosphonoenamines based on a modified Peterson olefination
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An efficient, stereoselective method for the synthesis of α-phosphonoenamines based on a modified Peterson olefination is described. The carbanion derived from isolatable intermediate 2 reacts with aromatic or aliphatic aldehydes selectively eliminating in Peterson fashion to deliver functionally rich α-phosphonoenamines 3. The synthetic utility of these enamines is demonstrated by their hydrolysis yielding the homologous carboxylic acids in good yield.
- McNulty, James,Das, Priyabrata,Gosciniak, Don
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p. 281 - 285
(2008/03/30)
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- Nitric acid in the presence of P2O5 supported on silica gel - A useful reagent for nitration of aromatic compounds under solvent-free conditions
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A variety of aromatic compounds are nitrated to parent nitro aromatic compounds under solvent-free conditions using 65% nitric acid in the presence of P2O5 supported on silica gel is described. This methodology is useful for nitration of activated and deactivated aromatic rings.
- Hajipour, Abdol Reza,Ruoho, Arnold E.
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p. 8307 - 8310
(2007/10/03)
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- A novel method for synthesis of arylacetic acids from aldehydes, N-(2,3,4,6-tetra-O-pivaloylated-D-glucopyranosyl)amine and trimethylsilylcyanide
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A novel synthetic approach for the preparation of arylacetic acids via the reaction of aldehydes, N-(2,3,4,6-tetra-O-pivaloylated-D-glucopyranosyl)amine and trimethylsilylcyanide was developed, in which the N-(2,3,4,6-tetra-O- pivaloylated-D-glucopyranosyl)amine can be recycled conveniently and reused efficiently.
- Zhou, Guo-Bin,Zhang, Peng-Fei,Pan, Yuan-Jiang
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p. 5671 - 5677
(2007/10/03)
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- Kinetics of Ru(III) catalysed oxidation of phenethyl alcohol and para-substituted phenethyl alcohols by Ce(IV) in aqueous nitric acid medium
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A simple, rapid and sensitive spectroscopic method for the kinetics of Ru(III) catalysed oxidation of phenthyl alcohol(PA) by Ce(IV) in aqueous nitric acid medium has been reported under varying conditions. The reaction is followed spectrophotometrically by measuring the decrease in absorbance of Ce(IV) at 350 nm. The rates show first order dependence on [Ce(IV)] and the rate constants evaluated at different [Ce(IV)] are found to be almost the same. Increase in [Ru(III)] has linear relation with the rate of oxidation and order in [Ru(III)] has been found to be fractional. Variation in ionic strength of the medium has significant effect on the rate of reaction. The rates of the reaction have been measured at different temperatures and the activation parameters for all the substrates computed. The rates decrease in the order - OCH3> -CH3 > -H>-Cl>-NO2 of para substituted phenethyl alcohols. Hammett's plot of log kobs versus σ is found to be valid. The correlation between enthalapies and free energies of activation is reasonably linear with an isokinetic temperature of 425K. The rate constant k obeys corresponding equation, k=Q.e-ΔE#RT,e ΔS#/R Ea increases with introduction of electron-withdrawing groups into the benzene ring. The introduction of electron-releasing groups lowers the Ea for the reaction. Similarly, logA decreases with substitution of electron-withdrawing groups and increases with substitution of electron-releasing groups. A plausible mechanism consistent with the experimental results has been proposed.
- Rao, N. Vijaya Bhaskar,Rao, M. Anand
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- A fast and mild method for nitration of aromatic rings
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The use of benzyltriphenylphosphonium nitrate (PhCH2Ph 3P+NO3-) (BTPPN) as a useful reagent for nitration aromatic compounds in the presence of methanesulfonic anhydride under solvent-free conditions is described. This methodology is useful for nitration of activated aromatic rings.
- Hajipour, Abdol R.,Ruoho, Arnold E.
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p. 221 - 226
(2007/10/03)
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- An efficient method for one-carbon elongation of aryl aldehydes via their dibromoalkene derivatives
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Various aryl aldehydes were efficiently converted into one-carbon extended aryl acetamides or aryl acetic acids through the reaction of their dibromoalkene derivatives with pyrrolidine in the presence of water under very mild conditions.
- Huh, Dal Ho,Jeong, Ji Sang,Lee, Hee Bong,Ryu, Hoejin,Kim, Young Gyu
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p. 9925 - 9932
(2007/10/03)
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- Induced thermolysis of tert-butyl phenylperacetates by thiophenol: Simultaneous occurrence of homolysis and single electron transfer
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Thermolysis of tert-butyl phenylperacetates in the presence of thiophenol takes place via dual mechanism. The two-bond homolysis indicates ρH+ = -1.16, testifying to polar transition states. The single electron transfer yields a radical anion intermediate which undergoes fragmentation with ρET = 1.01.
- Sung Soo Kim,Tuchkin,Chun Soo Kim
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p. 7738 - 7740
(2007/10/03)
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- Study of interactive free-energy relationships on ruthenium(III) catalyzed oxidation of phenyl styryl ketone and its substituted analogues by V(V) in acid medium
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Kinetics of Ru(III) catalyzed oxidation of phenyl styryl ketone (PSK) and its substituted analogues by V(V) has been investigated in aqueous acetic acid-sulphuric acid medium in the temperature range 298-313 K. First-order dependence each on [V(V)], [PSK], and [Ru(III)] was observed. Inverse first-order dependence was observed for [V(IV)]. The rate decreased with the increase in dielectric constant (D) of the medium. The rates were enhanced by electron-donating substituents in both the phenyl rings and decreased by electron-with-drawing substituents. Linear Hammett's plots were obtained for various substituents in benzaldehyde moiety of PSK for a given substituent in acetophenone moiety and vice versa. The mechanism proposed envisages formation of Ru(IV) from V(V)+Ru(III) reaction followed by the attack on C double bond O by Ru(IV). Applicability of interactive free-energy relationship has been tested. The cross-interaction constants qx and qy have been determined at different temperatures and possible interpretations discussed.
- Annapoorna,Prasad Rao,Sethuram
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p. 581 - 588
(2007/10/03)
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- Experiments on the Chaperon effect in the nitration of aromatics
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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
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p. 952 - 958
(2007/10/03)
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- An in-depth study of the biotransformation of nitriles into amides and/or acids using Rhodococcus rhodochrous AJ270
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A variety of aliphatic, aromatic and heterocyclic nitriles have been readily hydrolysed into the corresponding amides and/or acids under very mild conditions using Rhodococcus sp. AJ270. The nitrile hydratase involved in this novel nitrile-hydrolysing microorganism efficiently hydrates most nitriles tested, irrespective of the electronic and steric effects of the substituents, to form the amides. Conversion of amides into acids catalysed by the associated amidase is rapid and efficient in most cases. Substrates bearing an adjacent substituent (which may be an ortho substituent on an aromatic nitrile, an adjacent heteroatom in a heterocyclic ring or a geminal substituent in an α,β-unsaturated nitrile) undergo slow hydrolysis of the amides allowing efficient amide isolation. The scope, limitations and reaction mechanism of this enzymatic process have been systematically studied. A molecular size of >7 A diameter and the presence of functions capable of metal complexation near to the nitrile inhibit hydrolysis.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 1099 - 1104
(2007/10/03)
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- The potential application of catalytic antibodies to protecting group removal: Catalytic antibodies with broad substrate tolerance
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A catalytic antibody was developed to selectively cleave the alcohol ester of 4-nitrophenylacetyl moiety while also tolerating a wide variety of structural variation on the alcohol portion of the molecule. The basis to the success of this study was that antibody epitope recognition was directed toward only key elements contained within the 4-nitrophenylacetyl group and not the entire haptenic molecule. This study offers the potential application of catalytic antibodies as practical reagents for the selective deprotection of complex multifunctionalized molecules possessing class similar protecting groups. Such a chemoabzymatic approach could eventually minimize synthetic complications which can arise from functional group protection in the synthesis of complex natural products.
- Li,Hilton,Janda
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p. 2123 - 2127
(2007/10/02)
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- A Mild Oxidation of Aromatic Amines
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Several primary aromatic amines have been converted to the corresponding nitro compounds in good yields.The oxidant was oxone (potassium peroxymonosulfate) and the reactions were performed in 5 to 20percent aqueous acetone and buffered with sodium bicarbonate.
- Webb, Kevin S.,Seneviratne, Viran
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p. 2377 - 2378
(2007/10/02)
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- Orientation Effect of Side Chain Substituents in Aromatic Substitution. Induced Ortho Nitration
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The presence of a free carboxyl or ester function on the α-carbon of toluene induces the nitration of the phenyl ring in the ortho position at or above the statistical value (chaperon effect), when pure HNO3 is used in CH2Cl2 solution.This is at variance with the results of classical nitration in H2SO4, where p-nitration predominates by far and m-nitration occurs at a remarkable extent.The new finding is explained in terms of precomplex formation.
- Strazzolini, Paolo,Verardo, Giancarlo,Gorassini, Fausto,Giumanini, Angelo G.
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p. 1155 - 1161
(2007/10/02)
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- α-SUBSTITUIERTE PHOSPHONATE. 70. UNTERSUCHUNGEN UEBER METHYLTHIOMETHANBISPHOSPHORYLDERIVATE
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Thiophilic reaction of ethyl diphenylphosphinite with phosphonodithioformate 1 gave the ylid 9, which could be transformed with HCl to the bisphosphorylcompound 10.Chlorine reacted with 9 to the chlorinated bisphosphorylderivative 12b, with the ylid 2 analogously 12a was formed.With BTMS/H2O 10 could be dealkylated to the acid 11b, the bisphosphonate 3 in similar way to 11a.Using the Horner-method 3 was transformed to the methylthiovinylphosphonates 17, which could be converted to the acids 18 using the BTMS/H2O-method.Key-words: Methylthiomethane-bisphosphonic acid; alkoxyphosphoniumylid; Horner-reaction; methylthiovinylphosphonate.
- Costisella, Burkhard,Ozegowski, Sigrid,Gross, Hans
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p. 169 - 176
(2007/10/02)
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- Electronic Substituent Effects in the Nitrilase-Catalyzed Hydrolysis of Para-Substituted Benzyl Cyanides
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The initial rates of the nitrilase (Novo)-catalyzed hydrolysis of a series of para-substituted benzyl cyanides (R = NO2, Cl, OCH3, OH, NH2) were found to be susceptible to the nature of the para-substituent of the substrate and a Hammett-type linear free energy correlation was observed with ρ = 0.96.In a separate study, effective solubilization of substituted benzyl cyanide substrates having electron-donating groups (OH, NH2, OCH3) was achieved upon mixing with β-cyclodextrin to form 1:1 mol ratio inclusion complexes, but para-substituted benzyl cyanides with electron-withdrawing groups (Cl, NO2) were not fully solubilized under the same conditions.In addition, it was shown that the presence of β-cyclodextrin not only had no inhibitory effect on the enzyme activity, but it actually increased the initial rate of hydrolysis of the unsubstituted benzyl cyanide:β-cyclodextrin inclusion complex.However, the initial rates of hydrolysis were observed to be smaller when β-cyclodextrin was added to the para-substituted benzyl cyanides.
- Geresh, Shimona,Giron, Yakir,Gilboa, Ygal,Glaser, Robert
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p. 10099 - 10102
(2007/10/02)
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- Enzymic synthesis design and enzymic synthesis of aspartame
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An enzymic synthesis of aspartame (H-Asp-Phe-OMe) has been designed and realized based on the structure-activity study of thermolysin and penicillin amidase hydrolysis of its p-substituted phenylacetyl derivatives. These compounds meet the structural and energetic requirements of two enzymic binding sites. The peptide sweetener has been prepared by thermolysin - catalyzed condensation of the p-substituted phenylacetyl-Asp-OH and H-Phe-OMe follwed by penicillin amidase - catalyzed deprotection of the resulted aspartame precursors.
- Stoineva,Galunsky,Lozanov,Ivanov,Petkov
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p. 1115 - 1122
(2007/10/02)
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- Electrophilic Aromatic Substitution with N-Methoxy-N-acylnitrenium Ions Generated from N-Chloro-N-methoxyamides: Syntheses of Nitrogen Heterocyclic Compounds Bearing a N-Methoxyamide Group
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N-Methoxy-N-acylnitrenium ions (II), generated by treatment of N-chloro-N-methoxyamides with silver carbonate in trifluoroacetic acid, react with arenes to give N-aryl-N-methoxyamides in good yields.In the case of the intramolecular cyclization of N-chloro-N-methoxy-2-phenylacetamides, the mode of cyclization is highly dependent on the nature of ortho or para substituent groups.Nitrenium ions II can primarily attack three positions (C-1, C-2, and C-6) of a phenyl ring.Normally II attack C-6.On the other hand, when the ortho position was occupied with a substituent group, II attacked both C-2 and C-6, in the former case followed by a 1,2-substituent migration, which was proved by a deuterium labeling experiment.Especially, when a methoxy group is substituted on ortho or para position, II attack C-1 due to the effect of the electron-releasing methoxy group to give spiro dienone compounds 39.A general discussion of the utility and mechanistic details of these reactions is presented.
- Kawase, Masami,Kitamura, Takahiro,Kikugawa, Yasuo
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p. 3394 - 3403
(2007/10/02)
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- The E1cb Route for Ester Hydrolysis; Volumes of Activation as an Additional Criterion of Mechanism
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Hydrolyses of esters which possess an acidic proton at the α or vinylogous position can, in principle, hydrolyse by the E1cb route via a ketenoid intermediate.To the kinetic evidence for such a mechanism in the hydrolyses of 4-hydroxybenzoates, malonates, acetoacetates and fluorenecarboxylates is now added the further criterion of volumes of activation.Values of ΔV(excit.) for reactions proceeding by the E1cb route are positive and contrast with the negative values associated with hydrolyses by the more usual BAc2 mechanism.
- Isaacs, Neil S.,Najem, Tariq S.
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p. 557 - 562
(2007/10/02)
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- Electron Spin Resonance Studies. Part 71. Side-chain Oxidation Pathways in the Reactions of .OH and SO4-. with Some Phenyl-substituted Carboxylic Acids, their Anions, and Some related Compounds
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A series of arene radical-cations has been generated in situ by the reactions of methylbenzene, phenylethanoic acid, and some derivatives and cyclic analogues with both SO4-. and .OH (the latter in acid solution).The results are interpreted in terms of a variety of subsequent rapid reactions including hydration, deprotonation (to give benzylic radicals), and fragmentation (decarboxylation: for a series of radical-zwitterions +.Ar(CH2)nCO2- (n=1-3) decarboxylation (k >/= 1E9 dm3 mol-1 s-1) appears to proceed via direct intramolecular elecron-transfer, though in some cases formation of a discrete ?-bonded intermediate cannot be ruled out.
- Gilbert, Bruce C.,Scarratt, Cathryn J.,Thomas, C. Barry,Young, John
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p. 371 - 380
(2007/10/02)
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- Substituted sulfonamido compounds, photosensitive elements, film units, and processes for retaining a photographic image with same
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A nondiffusible sulfonamido compound which is alkali-cleavable upon oxidation to release a diffusible photographically useful material, said nondiffusible sulfonamido compound having the formula: STR1 wherein: (a) R1 is alkyl, aryl sulfamyl, carbamyl, carbonamido, carbonyl, carbonyloxy or sulfonamido; (b) R2 is alkyl having from 1 to 18 carbon atoms, aryl, or alkylphenyl having from 7 to 12 carbon atoms; (c) R3 and R4 are independently alkyl, or aryl, or R3 and R4, taken together, form a fused carbocyclic or heterocyclic ring; (d) NHSO2 PUG represents a sulfonamido group; (e) PUG represents a photographically useful group; and (f) at least one of R1, R2, R3, or R4, or any combination thereof, provides a molecular configuration of such size or shape as to render the compound nondiffusible under alkaline processing conditions, is useful as redox releaser in photosensitive elements, photographic film units and in processes for transferring and/or retaining a photographic image in color diffusion transfer units. These elements, film units and processes produce retained color images having substantially reduced minimum densities.
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- Ru(III) Catalysed Oxidation of Aryl Styryl Ketones by Periodate in Acid Medium: A Kinetic Study
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Oxidation of unsubstituted and substituted phenyl styryl ketones by periodate in the presence of Ru(III) is first order each in and and fractional order in .The rate of reaction increases with decrease in .Each mol of aryl styryl ketone consumes two mol of periodate for complete oxidation and the products have been identified as the corresponding substituted benzoic acids and phenylacetic acids.A probable mechanism involves the formation of a 1:1 complex between Ru(III) and the substrate which is oxidised by periodate to Ru(V) complex in rate-determining step which later dissociates to give products.
- Swarnalakshmi, N.,Uma, V.,Sethuram, B.,Navaneeth Rao, T.
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p. 386 - 388
(2007/10/02)
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- Hydrolysis of Esters and Amides in Strongly Basic Solution. Evidence for the Intermediacy of Carbanions
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Kinetic studies of the decomposition of the carbaninons derived from a number of esters and amides of p-nitrophenylacetic acid in strongly basic solution have been carried out.Kinetic solvents isotop effects and the large Hammett ρ value for substituents on the aromatic ring of substituted phenyl esters of p-nitrophenylacetic acid suggest decomposition occurs by an E1cB mechanism.Furthermore, it appears that the carbanion can decompose by either an ionic or a free-radical mechanism, depeneding on the nucleofugality of the leaving group.An intermediate predicted to be 4-nitrophenyl ketone ha been detected spestroscopically in a number of cases.
- Broxton Trevor, J.,Duddy, Neil W.
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p. 1186 - 1191
(2007/10/02)
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- Micellar Catalysis of the Basic Hydrolysis of Anilides. III α-Substituted N-Methyl-N-p-nitrophenylacetamides
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The basic hydrolysis of a number of α-substituted N-methyl-N-p-nitrophenylacetamides has been studied both in the presence and absence of micelles of cetyltrimethylammonium bromide (ctab).Unlike the related p-nitrophenyl esters of α-substituted acetic acids, no evidence for the operation of the E1cb mechanism in the basic hydrolysis has been detected.Reasons for the differences between the amides and esters are discussed.Substituent effects on the hydrolysis of the amides have been studied both by single-parameter and dual-parameter analysis.
- Broxton, Trevor J.,Duddy, Neil W.
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p. 1771 - 1781
(2007/10/02)
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