- Electrochemical detection of atrazine in wastewater samples by copper oxide (CuO) nanoparticles ionic liquid modified electrode
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In the present report, a new voltammetric sensor based on copper oxide nanoparticles involved in 2-(3-acetoxy-4-methoxybenzylidenamino)-thiophenol (AMT) ionic liquid (CuO NPs/ILs) was developed for atrazine (ATR) analysis. Firstly, the CuO NPs/ILs modifie
- Karda?, Faruk,Beytur, Murat,Aky?ld?r?m, Onur,Yüksek, Haydar,Yola, Mehmet Lütfi,Atar, Necip
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- Kolbe-Schmitt type reaction under ambient conditions mediated by an organic base
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The combined use of an organic base for resorcinols realized a Kolbe-Schmitt type reaction under ambient conditions. When resorcinols (3-hydroxyphenol derivatives) were treated with DBU under a carbon dioxide atmosphere, nucleophilic addition to carbon dioxide proceeded to afford the corresponding salicylic acid derivatives in high yields.
- Sadamitsu, Yuta,Okumura, Akira,Saito, Kodai,Yamada, Tohru
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supporting information
p. 9837 - 9840
(2019/08/20)
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- Synthesis and Biochemical Evaluation of 3-Phenoxy-1,4-diarylazetidin-2-ones as Tubulin-Targeting Antitumor Agents
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Structure-activity relationships for a series of 3-phenoxy-1,4-diarylazetidin-2-ones were investigated, leading to the discovery of a number of potent antiproliferative compounds, including trans-4-(3-hydroxy-4-methoxyphenyl)-3-phenoxy-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (78b) and trans-4-(3-amino-4-methoxyphenyl)-3-phenoxy-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (90b). X-ray crystallography studies indicate the potential importance of the torsional angle between the 1-phenyl A ring and 4-phenyl B ring for potent antiproliferative activity and that a trans configuration between the 3-phenoxy and 4-phenyl rings is generally optimal. These compounds displayed IC50 values of 38 and 19 nM, respectively, in MCF-7 breast cancer cells, inhibited the polymerization of isolated tubulin in vitro, disrupted the microtubular structure in MCF-7 cells as visualized by confocal microscopy, and caused G2/M arrest and apoptosis. Compound 90b possessed a mean GI50 value of 22 nM in the NCI60 cell line screen, displayed minimal cytotoxicity, and was shown to interact at the colchicine-binding site on β-tubulin. Phosphate and amino acid prodrugs of both 78b and 90b were synthesized, of which the alanine amide 102b retained potency and is a promising candidate for further clinical development.
- Greene, Thomas F.,Wang, Shu,Greene, Lisa M.,Nathwani, Seema M.,Pollock, Jade K.,Malebari, Azizah M.,McCabe, Thomas,Twamley, Brendan,OBoyle, Niamh M.,Zisterer, Daniela M.,Meegan, Mary J.
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- A modified Cu(0)-Cu(I)-mediated Caryl-CarylUllmann coupling for the synthesis of biaryls
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A novel Cu(0)-Cu(I)-mediated Caryl-CarylUllmann coupling has been successfully developed. The use of Cu(I) salts allowed the reactions to proceed under relatively mild conditions (65?°C in DMSO for 15–72?h). The developed method was compatible with a relatively wide range of functional groups simultaneously present on the aromatic ring of different electronic nature. The aryl halides with an electron-withdrawing group ortho to the halide or an electron-donating group meta or para to the halide furnished the corresponding products in good to excellent yields (up to 98%).
- Yasamut, Kittisak,Jongcharoenkamol, Jira,Ruchirawat, Somsak,Ploypradith, Poonsakdi
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p. 5994 - 6000
(2016/09/14)
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- Exploring the formation and recognition of an important G-quadruplex in a HIF1α promoter and its transcriptional inhibition by a benzo[c]phenanthridine derivative
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Four putative G-quadruplex sequences (PGSs) in the HIF1α promoter and the 5′UTR were evaluated for their G-quadruplex-forming potential using ESI-MS, CD, FRET, DMS footprinting, and a polymerase stop assay. An important G-quadruplex (S1) has been proven to inhibit HIF1α transcription by blocking AP2 binding. A benzo[c]phenanthridine derivative was found to target the S1 G-quadruplex and induce its conformational conversion from antiparallel to parallel orientation. The transcriptional suppression of HIF1α by this compound was demonstrated using western blotting, Q-RT-PCR, luciferase assay, and ChIP. Our new findings provided a novel strategy for HIF1α regulation and potential insight for cancer therapy.
- Chen, Han,Long, Haitao,Cui, Xiaojie,Zhou, Jiang,Xu, Ming,Yuan, Gu
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supporting information
p. 2583 - 2591
(2014/03/21)
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- Copper(I)-catalyzed intramolecular Caryl-O bond-forming cyclization for the synthesis of 1,4-benzodioxines and its application in the total synthesis of sweetening isovanillins
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Various substituted 1,4-benzodioxines were synthesized through an Ullmann-type intramolecular Caryl-O coupling cyclization reaction using a catalytic amount of BINOL-CuI complex. This methodology was successfully utilized as the key step in the total synthesis of isovanillyl sweetening agents 5-(2,3-dihydro-1,4-benzodioxin-2-yl)-2-methoxyphenol and 5-(2,3-dihydro-1,4-benz-oxathiin-2-yl)-2-methoxyphenol in 15.8% and 14.85% overall yields in five steps from isovanillin. Georg Thieme Verlag Stuttgart.
- Naidu, Ajay B.,Ganapathy,Sekar, Govindasamy
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experimental part
p. 3509 - 3519
(2010/12/19)
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- Convenient and clean synthesis of imines from primary benzylamines
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The current syntheses of imines from benzylamines are often performed in organic solvents or under harsh reaction conditions. Clean oxidation of primary benzylamines to imines has been successfully achieved using H2O 2 in water at room temperature catalyzed by V2O 5. Among the 10 imine products, 5 of them precipitated from the reaction and led pure products after simple filtration. No organic solvents are needed in the whole process. The yields are good to quantitative. This represents an efficient and green procedure of the synthesis of imines. A similar green oxidation of benzylamines to aromatic aldehydes is also reported. A benzylic anion-involved mechanism is proposed based on the experiments.
- Chu, Guobiao,Li, Chunbao
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supporting information; experimental part
p. 4716 - 4719
(2010/11/24)
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- Efficient and chemoselective deprotection of 1,1-diacetates using Fe 2(SO4)3·xH2O as a heterogeneous catalyst
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Various substituted 1,1-diacetates are smoothly transformed to the corresponding aldehydes by using hydrated ferric sulfate as heterogeneous catalyst at reflux in dichloroethane. The advantages of this methodology are: high yields, good chemoselectivity, inexpensive and environmentally benign catalyst as well as short reaction time and operational simplicity.
- Li, Lingjun,Zhang, Xinying,Zhang, Guisheng,Qu, Guirong
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- A mild and efficient deprotection of geminal diacetates catalysed by FeCl3·6H2O in ionic liquid
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The selective deprotection of geminal diacetates promoted by FeCl 3·6H2O in the ionic liquid, [bmim][BF4], can be efficiently achieved in good yield. The process is carried out under mild conditions, and the ionic liquid and the catalyst can be recycled easily.
- Niu, Hongying,Zhang, Xinying,Guo, Haiming,Wang, Jianji
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p. 764 - 765
(2007/10/03)
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- Syntheses of chlorinated bisbibenzyls from bryophytes
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Chlorinated bisbibenzyls of the isoplagiochin type detected in different bryophyte species were synthesized by an efficient and flexible unit construction system making extensive use of Suzuki and Wittig protocols.
- Speicher, Andreas,Kolz, Juergen,Sambanje, Rufino Paulino
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p. 2503 - 2512
(2007/10/03)
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- Stable isotope labeling pattern of resveratrol and related natural stilbenes.
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The stable isotope characterization of resveratrol 1 from Polygonum cuspidatum and of related natural stilbenes 11 and 12 obtained by hydrolysis of the corresponding glucosides 2 and 3 from Rheum is reported. The C(6)-C(2)-C(6) framework of suitably protected derivatives of 1, 2, and 3 has been degraded with ozone to the C(6)-C(1) aldehydes 4, 5, 9, and 10, retaining all hydrogen atoms of the precursors. The natural and synthetic derivatives are characterized and distinguished by natural abundance deuterium nuclear magnetic resonance studies. In the case of anisaldehyde 4 the two series show, as expected, the characteristic difference of the aromatic labeling. The formyl deuterium contents of 4 and 5 from resveratrol are remarkably different, seemingly reflecting the different enrichments existing between positions 3 and 2, respectively, of the phenylpropanoid precursor. The positional delta(18)O values of the extractive materials 1-3 were also determined. In this instance a selective deoxygenation procedure was adopted, leading from 1 to the products 6, 7, and 8. The delta(18)O values of the latter compounds reveal, respectively, those at position 4' and positions 3 and 5 of 1. Similarly, the phenolic products 11 and 12 were converted into 13 and 14. From the delta(18)O values of the single components it is possible to design a detailed map of the oxygen fractionations which characterizes the stilbenes 1-3. In particular, the oxygen present at position 4' of the phenylpropanoid moiety of 1-3 shows delta(18)O values of +11.5, +1.8, and +6.7 per thousand, respectively. Moreover, the phenolic oxygen atom at position 3' of rhapontin 3 shows a value of +11.7 per thousand. The data are compared with those previously obtained on structurally related compounds. These results show the utility of simple chemical degradations in the stable isotope characterization of structurally complex food components.
- Fronza, Giovanni,Fuganti, Claudio,Serra, Stefano,Cisero, Marco,Koziet, Joseph
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p. 2748 - 2754
(2007/10/03)
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- A Stereoselective Route to the Sugar-Cinnamate Unit of Hygromycin A
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Various aryl 6-deoxy-5-keto-β-D-arabino-hexofuranosides, including one (42) corresponding to the sugar-cinnamate unit of Hygromycin A (1) have been synthesized by a method in which 6-deoxy-β-D-glucofuranosides are first prepared, followed by configuration
- Buchanan, J. Grant,Hill, David G.,Wightman, Richard H.,Boddy, Ian K.,Hewitt, Brian D.
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p. 6033 - 6050
(2007/10/02)
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- Mechanistic Studies of Selective Catechol Formation from o-Methoxyphenols using a Copper(II)-Ascorbic Acid-Dioxygen System
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Mechanistic details of selective conversion of o-methoxyphenols to the corresponding catechols using a Cu2+-ascorbic acid-O2 system, were studied. 2,5-Dimethoxyphenol was converted predominantly to the o-demethylated compound and partially to the m-demethylated one.Anisole with no phenolic hydroxy group was much less reactive.When guaiacol (1). guaiacol and 2-methoxy-6-methoxyphenol was used as substrates, moderate intermolecular and intramolecular kinetic isotope effects were observed (1.4-1.9). Catechol was derived from 1 in nine-fold excess over catechol when the reaction was run in an 18O2 atmosphere with natural water as a solvent, though no catechol was formed when using natural O2 and H218O.It was determined that the Cu2+-ascorbic acid-O2 system operates in a monooxygenase mode because the oxygen atom of dioxygen (not water) was incorporated into the products, and this oxidative conversion proceeded mainly via ipso-substitution at the methoxy position, probably with hydroxyl radical coordinated to the cupric ion as the active oxygen species.
- Aihara, Kazuhiro,Urano, Yasuteru,Higuchi, Tsunehiko,Hirobe, Masaaki
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p. 2165 - 2170
(2007/10/02)
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- Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
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The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
- Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
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p. 5518 - 5523
(2007/10/02)
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