- Cloning and heterologous expression of two aryl-aldehyde dehydrogenases from the white-rot basidiomycete Phanerochaete chrysosporium
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We identified two aryl-aldehyde dehydrogenase proteins (PcALDH1 and PcALDH2) from the white-rot basidiomycete Phanerochaete chrysosporium. Both PcALDHs were translationally up-regulated in response to exogenous addition of vanillin, one of the key aromatic compounds in the pathway of lignin degradation by basidiomycetes. To clarify the catalytic functions of PcALDHs, we isolated full-length cDNAs encoding these proteins and heterologously expressed the recombinant enzymes using a pET/Escherichia coli system. The open reading frames of both PcALDH1 and PcALDH2 consisted of 1503 nucleotides. The deduced amino acid sequences of both proteins showed high homologies with aryl-aldehyde dehydrogenases from other organisms and contained ten conserved domains of ALDHs. Moreover, a novel glycine-rich motif "GxGxxxG" was located at the NAD+-binding site. The recombinant PcALDHs catalyzed dehydrogenation reactions of several aryl-aldehyde compounds, including vanillin, to their corresponding aromatic acids. These results strongly suggested that PcALDHs metabolize aryl-aldehyde compounds generated during fungal degradation of lignin and various aromatic xenobiotics.
- Nakamura, Tomofumi,Ichinose, Hirofumi,Wariishi, Hiroyuki
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- Cytotoxic cholestane glycosides from the bulbs of Ornithogalum saundersiae
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Further phytochemical analysis of the bulbs of Ornithogalum saundersiae has yielded two new cytotoxic cholestane triglycosides (1 and 2). The structures of these compounds were determined by spectroscopic analysis, including 2D NMR spectroscopic data, and
- Kuroda, Minpei,Mimaki, Yoshihiro,Yokosuka, Akihito,Sashida, Yutaka,Beutler, John A.
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- One pot synthesis of α-aminophosphonates containing bromo and 3,4,5-trimethoxybenzyl groups under solvent-free conditions
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New α-aminophosphonates were synthesized by the Kabachnik-Fields reaction of 3,4,5-trimethoxybenzaldehyde (TMB) with p- or m-bromoaniline and a dialkyl phosphite under solvent-free conditions. TMB was prepared from gallic acid via a four step synthetic sequence involving etherification, esterification, hydrazidation and potassium ferricyanide oxidation. The structures of all synthesized compounds were confirmed by elemental analysis, IR, 1H-, 13C- and 31P-NMR spectral data. Compound 7g was also characterized by X-ray crystallography. A half-leaf method was used to determine the in vivo curative efficacy of the eight title products against tobacco mosaic virus (TMV). It was found that compounds 7g and 7h possess good in vivo curative effects against TMV.
- Li, Caihong,Song, Baoan,Yan, Kai,Xu, Gangfang,Hu, Deyu,Yang, Song,Jin, Linhong,Xue, Wei,Lu, Ping
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- ALSTOLENINE, 19,20-DIHYDROPOLYNEURIDINE AND OTHER MINOR ALKALOIDS OF THE LEAVES OF ALSTONIA VENENATA
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Structures of alstolenine and 19,20-dihydropolyneuridine, two new indole alkaloids of the leaves of Alstonia venenata have been established.In addition, deacetylakuammiline, polyneuridine and raucaffrinoline have been isolated for the first time from this plant.Key Word Index-Alstonia venenata; Apocynaceae; alstolenine; 19,20-dihydropolyneuridine; polyneuridine; deacetylakuammiline; raucaffrinoline; indol alkaloids.
- Majumder, Priyalal,Basu, Ashoke
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- The Selective Liquid-Phase Oxidation of 3,4,5-Trimethoxytoluene to 3,4,5-Trimethoxybezaldehyde
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The selective liquid-phase oxidation of 3,4,5-trimethoxytoluene to 3,4,5-trimethoxybenzaldehyde, an important chemical intermediate for medicine production, was developed; when 2.0 mmol of the reactant was heated at 110 deg C for 2 h in an autoclave under 3 atm O2 with 10 ml of acetic acid in the presence of 0.75 mmol of Co(OAc)2-Mn(OAc)2 (3:1 mol ratio), a 92percent yield of the aldehyde was obtained.
- Kitajima, Nobumasa,Takemura, Kazuya,Moro-Oka, Yoshihiko,Yoshikuni, Tadatsugu,Akada, Mitsuo,et al.
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- Solvolysis, Electrochemistry, and Development of Synthetic Building Blocks from Sawdust
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Either aldehyde or cinnamyl ether products can be selectively extracted from raw sawdust by controlling the temperature and pressure of a solvolysis reaction. These materials have been used as platform chemicals for the synthesis of 15 different synthetic substrates. The conversion of the initial sawdust-derived materials into electron-rich aryl substrates often requires the use of oxidation and reduction chemistry, and the role electrochemistry can play as a sustainable method for these transformations has been defined.
- Nguyen, Bichlien H.,Perkins, Robert J.,Smith, Jake A.,Moeller, Kevin D.
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- Synthesis and antitumor activity of novel 6,7,8-trimethoxy N-aryl-substituted-4-aminoquinazoline derivatives
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A series of 6,7,8-trimethoxy N-aryl-substituted-4-aminoquinazoline derivatives were synthesized as epidermal growth factor receptor (EGFR) inhibitors, and their antitumor activities were assessed in the gastric cancer cell line SGC7901 using MTT assay. All compounds of Tg1–14 were found to inhibit SGC7901 cell proliferation, and compound Tg11 (IC50 = 0.434 μM) was found to be slightly more effective against SGC7901 cells than epirubicin (IC50 = 5.16 μM). This suggests that compound Tg11 can be used as a new substitution structure to develop more efficacious antitumor agents. Western blot analysis showed that treatment with Tg11 (40 μM for 30 min) resulted in near complete inhibition of EGF-induced ERK1/2 phosphorylation, indicating that its anti-proliferative effect is largely associated with inhibition of ERK1/2 activation. These data imply that Tg11 is a potential anticancer agent capable of inhibiting cell proliferation.
- Liu, Fang,Huai, Ziyou,Xia, Guotai,Song, Liuping,Li, Sha,Xu, Yulan,Hong, Kangjun,Yao, Mingyue,Liu, Gang,Huang, Yinjiu
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- One-Pot Biocatalytic In Vivo Methylation-Hydroamination of Bioderived Lignin Monomers to Generate a Key Precursor to L-DOPA
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Electron-rich phenolic substrates can be derived from the depolymerisation of lignin feedstocks. Direct biotransformations of the hydroxycinnamic acid monomers obtained can be exploited to produce high-value chemicals, such as α-amino acids, however the reaction is often hampered by the chemical autooxidation in alkaline or harsh reaction media. Regioselective O-methyltransferases (OMTs) are ubiquitous enzymes in natural secondary metabolic pathways utilising an expensive co-substrate S-adenosyl-l-methionine (SAM) as the methylating reagent altering the physicochemical properties of the hydroxycinnamic acids. In this study, we engineered an OMT to accept a variety of electron-rich phenolic substrates, modified a commercial E. coli strain BL21 (DE3) to regenerate SAM in vivo, and combined it with an engineered ammonia lyase to partake in a one-pot, two whole cell enzyme cascade to produce the l-DOPA precursor l-veratrylglycine from lignin-derived ferulic acid.
- Birmingham, William R.,Galman, James L.,Parmeggiani, Fabio,Seibt, Lisa,Turner, Nicholas J.
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- Merging N-Hydroxyphthalimide into Metal-Organic Frameworks for Highly Efficient and Environmentally Benign Aerobic Oxidation
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Two highly efficient metal-organic framework catalysts TJU-68-NHPI and TJU-68-NDHPI have been successfully synthesized through solvothermal reactions of which the frameworks are merged with N-hydroxyphthalimide (NHPI) units, resulting in the decoration of pore surfaces with highly active nitroxyl catalytic sites. When t-butyl nitrite (TBN) is used as co-catalyst, the as-synthesized MOFs are demonstrated to be highly efficient and recyclable catalysts for a novel three-phase heterogeneous oxidation of activated C?H bond of primary and secondary alcohols, and benzyl compounds under mild conditions. Based on the high efficiency and selectivity, an environmentally benign system with good sustainability, mild conditions, simple work-up procedure has been established for practical oxidation of a wide range of substrates.
- Wang, Man,Liang, Gan,Wang, Yunhao,Fan, Tao,Yuan, Baoling,Liu, Mingxian,Yin, Ying,Li, Liangchun
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supporting information
p. 9674 - 9685
(2021/06/09)
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- Selectively Upgrading Lignin Derivatives to Carboxylates through Electrochemical Oxidative C(OH)?C Bond Cleavage by a Mn-Doped Cobalt Oxyhydroxide Catalyst
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Oxidative cleavage of C(OH)?C bonds to afford carboxylates is of significant importance for the petrochemical industry and biomass valorization. Here we report an efficient electrochemical strategy for the selective upgrading of lignin derivatives to carboxylates by a manganese-doped cobalt oxyhydroxide (MnCoOOH) catalyst. A wide range of lignin-derived substrates with C(OH)-C or C(O)-C units undergo efficient cleavage to corresponding carboxylates in excellent yields (80–99 %) and operational stability (200 h). Detailed investigations reveal a tandem oxidation mechanism that base from the electrolyte converts secondary alcohols and their derived ketones to reactive nucleophiles, which are oxidized by electrophilic oxygen species on MnCoOOH from water. As proof of concept, this approach was applied to upgrade lignin derivatives with C(OH)-C or C(O)-C motifs, achieving convergent transformation of lignin-derived mixtures to benzoate and KA oil to adipate with 91.5 % and 64.2 % yields, respectively.
- Zhou, Hua,Li, Zhenhua,Xu, Si-Min,Lu, Lilin,Xu, Ming,Ji, Kaiyue,Ge, Ruixiang,Yan, Yifan,Ma, Lina,Kong, Xianggui,Zheng, Lirong,Duan, Haohong
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supporting information
p. 8976 - 8982
(2021/03/16)
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- Polyhydroxybenzoic acid derivatives as potential new antimalarial agents
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With more than 200 million cases and 400,000 related deaths, malaria remains one of the deadliest infectious diseases of 2021. Unfortunately, despite the availability of efficient treatments, we have observed an increase in people infected with malaria since 2015 (from 211 million in 2015 to 229 million in 2019). This trend could partially be due to the development of resistance to all the current drugs. Therefore, there is an urgent need for new alternatives. We have, thus, selected common natural scaffolds, polyhydroxybenzoic acids, and synthesized a library of derivatives to better understand the structure–activity relationships explaining their antiplasmodial effect. Only gallic acid derivatives showed a noticeable potential for further developments. Indeed, they showed a selective inhibitory effect on Plasmodium (IC50 ~20 μM, SI > 5) often associated with interesting water solubility. Moreover, this has confirmed the critical importance of free phenolic functions (pyrogallol moiety) for the antimalarial effect. Methyl 4-benzoxy-3,5-dihydroxybenzoate (39) has, for the first time, been recognized as a potential lead for future research because of its marked inhibitory activity against Plasmodium falciparum and its significant hydrosolubility (3.72 mM).
- Degotte, Gilles,Francotte, Pierre,Pirotte, Bernard,Frédérich, Michel
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- Synthesis and antioxidant activities of berberine 9-: O -benzoic acid derivatives
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Although berberine (BBR) shows antioxidant activity, its activity is limited. We synthesized 9-O-benzoic acid berberine derivatives, and their antioxidant activities were screened via ABTS, DPPH, HOSC and FRAP assays. The para-position was modified with halogen elements on the benzoic acid ring, which led to an enhanced antioxidant activity and the substituent on the ortho-position was found to be better than the meta-position. Compounds 8p, 8c, 8d, 8i, 8j, 8l, and especially 8p showed significantly higher antioxidant activities, which could be attributed to the electronic donating groups. All the berberine derivatives possessed proper lipophilicities. In conclusion, compound 8p is a promising antioxidant candidate with remarkable elevated antioxidant activity and moderate lipophilicity.
- Liu, Yanfei,Long, Shuo,Zhang, Shanshan,Tan, Yifu,Wang, Ting,Wu, Yuwei,Jiang, Ting,Liu, Xiaoqin,Peng, Dongming,Liu, Zhenbao
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p. 17611 - 17621
(2021/05/29)
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- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
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The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
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supporting information
p. 9140 - 9146
(2021/11/23)
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- Synthesis, characterization (theoretical and biological study) of some transition metal complexes with new schiff base derived from 1,2,4-triazole
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The present work involves, new Schiff base of (E)-2-(((3-mercapto-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazol-4-yl)imino)methyl)phenol (L2) has been synthesized by condensation reaction of 4-amino-5-(3,4,5 trimethoxy phenyl)-4H-1,2,4-triazole-3-thiol with 2-hydroxybenzaldehyde. The new Schiff base (L2) used as a ligand to synthesize a new complex with Co(II), Ni(II), Cu(II), Pd(II), and Cd(II) metal ions by 1:1 (Metal: ligand) ratio. New ligand and their complexes have been exanimated and confirmed by fourier-transform infrared (FT-IR), ultraviolet-visible (UV-visible), proton nuclear magnetic resonance (1HNMR), carbon13 nuclear magnetic resonance (13CNMR), microelement analysis (CHNS), thermal analysis (TG-DSC), atomic absorption flame (AAF), conductivity and magnetic susceptibility. The results obtained from spectra, elemental analyses and thermal analyses (TG-DSC) and compare by density functional theory (DFT) and TD-DFT calculations were screened for some selected complexes and the observed data indicated their stability and the expected chemical formula, Pd(II) were square planner, whereas the Cu(II), Co(II), Ni(II) octahedral, and Cd(II) were tetrahedral geometry . Furthermore, the antibacterial and antifungal activity was screened for the DMSO solution concerning the Schiff base (L2) and its complexes (20 μg/ml) against two kinds of gram; (Staphylococcus aureas and Bacillus subtilis) positive and two negative bacteria; (Esherichia coli and Burkholderia) and against (Candida albican) fungi. The results obtained from diffusion method confirmed the greater activity of Pd(II) and Cd(II) complexes whereas the Co(II),Cu(II) and Ni(II) complexes showed medium activity compared with the low inhibition zones of the free Schiff base of 1, 2, 4- triazole derivative.
- AL-Jibouri, Mahmoud Najim,Jawad, Waleed A.,Balakit, Asim A.,Obies, Mohammed
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p. 5229 - 5241
(2021/08/31)
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- Mechanochemical cleavage of lignin models and ligninviaoxidation and a subsequent base-catalyzed strategy
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Mechanochemical cleavage of lignin dimer model compounds to phenolic monomers has been developedviaa two-step strategy under milling conditions. In the first step of this process, the secondary benzylic alcohol of lignin β-O-4 linkages was selectively oxidized to the corresponding ketones over a 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)/NaNO2catalytic system under milling conditions. In the subsequent step, mechanochemical selective cleavage of the Cβ-O bonds and Cα-Cβbonds of lignin β-O-4 ketones to acids and phenols was promoted by NaOH-catalyzed depolymerization. In addition, this two-step strategy was performed to depolymerize organosolv birch lignin, giving aromatic monomers with good selectivity for syringate. This approach provides an efficient method to convert the β-O-4 linkages of lignin to valuable aromatic monomers under mild reaction conditions.
- Dushkin, Alexandr V.,Su, Weike,Sun, Chen,Xu, Wenhao,Zheng, Lei
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p. 3489 - 3494
(2020/07/30)
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- Palladium-catalyzed carbonylative synthesis of acylstannanes from aryl iodides and hexamethyldistannane
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In this communication, we describe a new method for the carbonylative synthesis of acylstannanes from aryl iodides and hexamethyldistannane. With Pd(PPh3)4 as the catalyst and toluene as the solvent at 60 °C under 10 bar CO for 16 h, the desired acylstannanes were obtained in good to excellent yields. In order to facilitate isolation and analysis, the obtained acylstannanes were transformed into the corresponding benzoic acids by simply stirring under air for 5 h.
- Chen, Bo,Franke, Robert,Wu, Xiao-Feng,Xu, Jian-Xing,Yuan, Yang
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- A cyclometalated Ir(iii)-NHC complex as a recyclable catalyst for acceptorless dehydrogenation of alcohols to carboxylic acids
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In this work, we have synthesized two new [C, C] cyclometalated Ir(iii)-NHC complexes, [IrCp?(C∧C:NHC)Br](1a,b), [Cp? = pentamethylcyclopentadienyl; NHC = (2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazoline-2-ylidene (a); (2-flurobenzyl)-1-(4-formylphenyl)-1H-imidazoline-2-ylidene (b)] via intramolecular C-H bond activation. The molecular structure of complex 1a was determined by X-ray single crystal analysis. The catalytic potentials of the complexes were explored for acceptorless dehydrogenation of alcohols to carboxylic acids with concomitant hydrogen gas evolution. Under similar experimental conditions, complex 1a was found to be slightly more efficient than complex 1b. Using 0.1 mol% of complex 1a, good-to-excellent yields of carboxylic acids/carboxylates have been obtained for a wide range of alcohols, both aliphatic and aromatic, including those involving heterocycles, in a short reaction time with a low loading of catalyst. Remarkably, our method can produce benzoic acid from benzyl alcohol on a gram scale with a catalyst-to-substrate ratio as low as 1?:?5000 and exhibit a TON of 4550. Furthermore, the catalyst could be recycled at least three times without losing its activity. A mechanism has been proposed based on controlled experiments and in situ NMR study.
- Borah, Dhrubajit,Das, Pankaj,Saha, Biswajit,Sarma, Bipul
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p. 16866 - 16876
(2020/12/18)
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- Tubulin inhibitors: Discovery of a new scaffold targeting extra-binding residues within the colchicine site through anchoring substituents properly adapted to their pocket by a semi-flexible linker
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Bis-hydrazides 13a-h were designed and synthesized as potential tubulin inhibitors selectively targeting the colchicine site between α- and β-tubulin subunits. The newly designed ring-B substituents were assisted at their ends by ‘anchor groups’ which are expected to exert binding interaction(s) with new additional amino acid residues in the colchicine site (beyond those amino acids previously reported to interact with reference inhibitors as CA-4 and colchicine). Conformational flexibility of bis-hydrazide linker assisted these ‘extra-binding’ properties through reliving ligands’ strains in the final ligand-receptor complexes. Compound 13f displayed the most promising computational and biological study results in the series: MM/GBSA binding energy of ?62.362 kcal/mol (extra-binding to Arg α:221, Thr β:353 & Lys β:254); 34% NCI-H522 cells’ death (at 10 μM), IC50 = 0.073 μM (MTT assay); significant cell cycle arrest at G2/M phase; 11.6% preG1 apoptosis induction and 83.1% in vitro tubulin inhibition (at concentration = IC50). Future researchers in bis-hydrazide tubulin inhibitors are advised to consider the 2-chloro-N-(4-substituted-phenyl)acetamide derivatives as compound 13f due to extra-binding properties of their ring B.
- AbdelHafez, El-Shimaa M. N.,Abdelhamid, Dalia,Aly, Omar M.,Maklad, Raed M.
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supporting information
(2020/04/22)
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- Nobiletin derivative or pharmaceutically acceptable salt thereof as well as preparation method and application thereof
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The invention discloses a nobiletin derivative or a pharmaceutically acceptable salt thereof as well as a preparation method and application thereof. The nobiletin derivative has a structural formula(I) shown in the description, in the formula, R1, R2, R3 and R4 are respectively selected from hydrogen, halogen, hydroxyl, amino, C1-6 substituted or non-substituted alkoxy, a C1-6 substituted or non-substituted ester group, C1-6 substituted or non-substituted alkamino and a C1-6 substituted or non-substituted amide group; R5 is selected from a C3-9 substituted or non-substituted aromatic ring and a C3-9 substituted or non-substituted aromatic heterocyclic ring; and X is selected from O or NR6. The nobiletin derivative or the pharmaceutically acceptable salt thereof, which is disclosed by theinvention, is novel in structure, and in addition, the compound has an excellent inhibition function on P-gp, can be prepared into a P-gp inhibitor, is capable of treating and/or preventing related diseases caused by P-gp, particularly diseases related to tumor drug resistance, or can be mixed and used with other medicines and used as a drug resistance reversal agent, has a high reversion multiple, and is capable of remarkably improving medicine effects of medicines.
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Paragraph 0097-0099; 0101
(2019/12/09)
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- Pd(II)-Catalyzed asymmetric oxidative annulation of N-alkoxyheteroaryl amides and 1,3-dienes
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The first Pd(II)-catalyzed asymmetric oxidative annulation of N-alkoxyaryl amides and 1,3-dienes is reported, which features particular applicability for quick assembly of different types of chiral heterocycles with high yields and enantioselectivities. A novel chiral pyridine-oxazoline bearing a methoxyl group at the C-5 position and a gem-dimethyl group on the oxazoline moiety was found to be crucial for conversion.
- Zhang, Tao,Shen, Hong-Cheng,Xu, Jia-Cheng,Fan, Tao,Han, Zhi-Yong,Gong, Liu-Zhu
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supporting information
p. 2048 - 2051
(2019/03/29)
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- I2/Fe(NO3)3·9H2O-catalyzed oxidative synthesis of aryl carboxylic acids from aryl alkyl ketones and secondary benzylic alcohols
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An interesting and convenient procedure for the oxidative transformation of aryl alkyl ketones and secondary benzylic alcohols to aryl carboxylic acids has been developed. By using iodine and Fe(NO3)3·9H2O as the catalysts, DMSO and oxygen as the oxidants, the desired aryl carboxylic acids were synthesized in moderate to excellent yields (up to 91%).
- Xu, Liang,Chen, Yingying,Shen, Zhenlu,Wang, Yuru,Li, Meichao
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p. 4349 - 4354
(2018/11/03)
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- Catalytic oxidation synthetic method of benzoic acid compound
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The invention discloses a catalytic oxidation synthetic method of a benzoic acid compound. According to the invention, secondary benzylalcohol is used as a reaction substrate, iodine and Fe(NO3)3.9H2Oare used as a catalyst, under oxygen atmosphere of atmospheric pressure, in dimethyl sulfoxide (DMSO), the materials are reacted for 8-16 h at the temperature of 110-140 DEG C, and after the reactionis completed, performing separating processing to obtain the benzoic acid compound. The synthetic method uses an iron-based catalyst which is friendly to environment, a green oxidizing agent oxygen which is friendly to environment is used, the reaction is carried out under normal pressure, and pressurization equipment is not required.
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Paragraph 0058-0059
(2018/11/26)
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- Three-dimensional composite of Co3O4 nanoparticles and nitrogen-doped reduced graphene oxide for lignin model compound oxidation
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A three-dimensional composite of Co3O4 nanoparticles and nitrogen-doped reduced graphene oxide (3D Co3O4/N-rGO) with a unique 3D porous structure was prepared, and its catalytic activity in lignin model compound oxidation was explored. The 3D Co3O4/N-rGO composite exhibits improved catalytic performance as compared to Co3O4 nanoparticles or 3D N-rGO in the oxidation of lignin model compounds. The higher catalytic activity of the 3D Co3O4/N-rGO composite is attributed to the combination of its porous structural features, large surface area that is provided by the 3D N-rGO matrix, and active Co3O4 nanoparticles doped on the N-rGO surface. The structural features of the 3D Co3O4/N-rGO are beneficial to reactant and product diffusion and transportation, and also are helpful in preventing aggregation of Co3O4 nanoparticles. In addition, the introduction of N atoms in rGO is also favorable for the formation of active oxygen species for the oxidation of model compounds. Given the high activity and the easy recovery from the reaction system, the 3D Co3O4/N-rGO composite should be applicable to non-noble metal catalytic systems for lignin model compounds.
- Zhang, Jiali,Zhang, Fangwei,Guo, Shouwu,Zhang, Jingyan
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p. 11117 - 11123
(2018/07/05)
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- Method for preparing aryl formic acid by adopting aryl alkyl ketone as raw material
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The invention discloses a method for preparing aryl formic acid by adopting aryl alkyl ketone as a raw material. The method is characterized in that: aryl alkyl ketone is used as a reaction substrate,iodine and Fe(NO3)3.9H2O are used catalysts to react for 8 to 16 hours in dimethyl sulfoxide at the temperature 110 to 140 DEG C in an oxygen atmosphere of one barometric pressure, and after the reaction is ended, the reactant is separated to obtain the aryl formic acid. According to the synthetic method of the invention, the environment-friendly iron catalyst is used; the environment-friendly green oxidant oxygen is used; the reaction is performed at the normal pressure, and no pressurizing device is needed; and the application range of the reaction substrate is wide.
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Paragraph 0093; 0094
(2019/01/08)
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- Synthesis and in vitro antimalarial activity of alkyl esters of gallate as a growth inhibitor of plasmodium falciparum
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This study is aimed to synthesize alkyl esters gallate and determine its in vitro antimalarial activity against parasite Plasmodium falciparum. Fourteen compounds of alkyl esters gallate were synthesized by esterification of the carboxyl group of gallic acid with a series of alkyl alcohols, as well as methoxylation of the hydroxy groups on the aromatic ring of gallic acid. Antimalarial activity of the synthesized alkyl esters gallate were expressed by IC50 value, with gallic acid as an original compound and artemisin as a positive control. Compared to gallic acid, eleven synthesized compounds of alkyl esters gallate, have a greater antimalarial activity against Plasmodium falciparum. On the other hand, three compounds, that are propyl gallate, butyl gallate and trimethoxy methyl gallate, showed a lower antimalarial activity. Moreover, compared to gallic acid (IC50: 194.86 mM) and artemisin (IC50: 0.5 mM), two synthesized compounds of alkyl gallates, namely methyl gallate and hexyl gallate exhibited the stronger antimalarial activity against Plasmodium falciparum, with IC50 value of 0.03 mM and 0.11 mM, respectively. Our result clearly demonstrated that methyl gallate and hexyl gallate as a promising candidate for the new antimalarial agents.
- Arsianti, Ade,Astuty, Hendri,Fadilah,Simadibrata, Daniel Martin,Adyasa, Zoya Marie,Amartya, Daniel,Bahtiar, Anton,Tanimoto, Hiroki,Kakiuchi, Kiyomi
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p. 655 - 662
(2018/05/28)
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- A mild method for synthesizing carboxylic acids by oxidation of aldoximes using hypervalent iodine reagents
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A mild oxidation method for the conversion of aldoximes to carboxylic acids was developed mediated by hypervalent iodine reagents. This method covers a wide range of functionalized aldoximes and proceeds under mild conditions, utilizing PhI(OH)OTs as an oxidant.
- Nakamura, Akira,Kanou, Hodaka,Tanaka, Junki,Imamiya, Akira,Maegawa, Tomohiro,Miki, Yasuyoshi
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supporting information
p. 541 - 544
(2018/02/07)
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- Sea Urchin Embryo Model As a Reliable in Vivo Phenotypic Screen to Characterize Selective Antimitotic Molecules. Comparative evaluation of Combretapyrazoles, -isoxazoles, -1,2,3-triazoles, and -pyrroles as Tubulin-Binding Agents
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A series of both novel and reported combretastatin analogues, including diarylpyrazoles, -isoxazoles, -1,2,3-triazoles, and -pyrroles, were synthesized via improved protocols to evaluate their antimitotic antitubulin activity using in vivo sea urchin embryo assay and a panel of human cancer cells. A systematic comparative structure-activity relationship studies of these compounds were conducted. Pyrazoles 1i and 1p, isoxazole 3a, and triazole 7b were found to be the most potent antimitotics across all tested compounds causing cleavage alteration of the sea urchin embryo at 1, 0.25, 1, and 0.5 nM, respectively. These agents exhibited comparable cytotoxicity against human cancer cells. Structure-activity relationship studies revealed that compounds substituted with 3,4,5-trimethoxyphenyl ring A and 4-methoxyphenyl ring B displayed the highest activity. 3-Hydroxy group in the ring B was essential for the antiproliferative activity in the diarylisoxazole series, whereas it was not required for potency of diarylpyrazoles. Isoxazoles 3 with 3,4,5-trimethoxy-substituted ring A and 3-hydroxy-4-methoxy-substituted ring B were more active than the respective pyrazoles 1. Of the azoles substituted with the same set of other aryl pharmacophores, diarylpyrazoles 1, 4,5-diarylisoxazoles 3, and 4,5-diaryl-1,2,3-triazoles 7 displayed similar strongest antimitotic antitubulin effect followed by 3,4-diarylisoxazoles 5, 1,5-diaryl-1,2,3-triazoles 8, and pyrroles 10 that showed the lowest activity. Introduction of the amino group into the heterocyclic core decreased the antimitotic antitubulin effect of pyrazoles, triazoles, and to a lesser degree of 4,5-diarylisoxazoles, whereas potency of the respective 3,4-diarylisoxazoles was increased.
- Semenova, Marina N.,Demchuk, Dmitry V.,Tsyganov, Dmitry V.,Chernysheva, Natalia B.,Samet, Alexander V.,Silyanova, Eugenia A.,Kislyi, Victor P.,Maksimenko, Anna S.,Varakutin, Alexander E.,Konyushkin, Leonid D.,Raihstat, Mikhail M.,Kiselyov, Alex S.,Semenov, Victor V.
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p. 700 - 721
(2019/01/03)
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- Synthesis and cytotoxic activities of hexyl-esters derivatives of gallic acid against MCF-7 cell line
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Gallic acid is found in many plants, fruits, and foods where the anti-cancer activity is found. However, gallic acid has a problem on the high polarity and low bio availability. So, it takes molecular modifications in order to increase its lipophilicity, which is expected to increase bio availability and cytotoxic activity of gallic acid. Hexyl esters derivatives of gallic acid were synthesized and characterized by spectrometer 1H-NMR, 13C-NMR, mass spectrometry and infrared spectrophotometer (FTIR). All compounds were then evaluated for cytotoxic activity on MCF-7 cell line using MTT method. Compound cis-2′-hexenyl-3,4,5-trimethoxygallate (19) had the lowest IC50 value compared with gallic acid and other derivatives hexyl esters. IC50 value of cis-2′-hexenyl-3,4,5-trimethoxygallate (19) is 14.48 μg/ml. Compound (19) also has approached with IC50 values of gossypol as a positive control. Compound (19) is a potential compound to inhibit growth of MCF-7 cell line.
- Paramita, Rafika Indah,Arsianti, Ade,Radji, Maksum
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p. 295 - 300
(2018/03/21)
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- Temperature-controlled solvent-free selective synthesis of tert-butyl peresters or acids from benzyl cyanides in the presence of the TBHP/Cu(OAc)2 system
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Solvent-free room temperature synthesis of tert-butyl peresters was achieved via copper-catalyzed oxidative-coupling of benzyl cyanides with tert-butyl hydroperoxide in short reaction times. Various derivatives of tert-butyl peresters were synthesized by this pathway in good to excellent yields. Further investigation revealed that the above-mentioned protocol is effective for the synthesis of benzoic acid derivatives when the reaction is conducted at 80?°C, under the same reaction conditions.
- Hashemi,Saberi,Poorsadeghi,Niknam
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p. 7619 - 7622
(2017/02/05)
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- Gallic acid acylated derivatives having anticancer activity and use thereof
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The invention discloses gallic acid acylated derivatives having anticancer activity. The gallic acid acylated derivatives have a structural formula shown in the description. The acylated derivatives provided by the invention have good activity to oral cancer cells, have good selectivity and have a good clinical application value.
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- Catalyst-free aerobic oxidation of aldehydes into acids in water under mild conditions
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The first example of catalyst-free aerobic oxidation of aldehydes in water under respective acidic, neutral and alkaline conditions was developed. The sole oxidant is molecular oxygen of 1 atmosphere and reactions can proceed under extremely mild conditions. This procedure covers a wide range of aldehydes, and operates easily. No additives and catalysts were required for this purpose, and most of the aldehydes can be converted to their corresponding carboxylic acids with good to excellent yields, in addition, no side-product formation could be observed during or after the reactions. To well illustrate why the oxidation rate becomes fast firstly and then slows with increased temperatures, five control reactions were carried out and a Fe3+/Fe2+ recycling system was introduced to facilitate the aldehyde oxidation rate. The generality of this method offers the potential for industrial aldehyde-containing waste water treatment.
- Zhang, Yue,Cheng, Yujia,Cai, Huizhuo,He, Shaopo,Shan, Qiheng,Zhao, Hongwei,Chen, Yiping,Wang, Bo
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supporting information
p. 5708 - 5713
(2017/12/06)
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- Synthesis and Biological Activity of Novel (E)-N′-(Substituted)-3,4,5-trimethoxybenzohydrazide Analogs
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The hydrazide-hydrazone analogs 4a-4l is described via the condensation of 3,4,5-trimethoxybenzohydrazide 3 with various aromatic and hetero aromatic aldehydes a-l. Various spectroscopic techniques viz., (1H NMR, 13C NMR, IR and MS) were utilized to determine the structures of synthesized compounds. These compounds were evaluated for antibacterial, antifungal screening against S.aureus, S.pyogenes, E.coli, P.aeruginosa, Aspergillus niger and Candida albicans (Fungal strains). The results revealed that most of the hydrazone derivatives exhibited significant antibacterial activity. Furthermore, the synthesized hydrazone derivatives were found to exhibit significant antidiabetic activity when compared to insulin.
- Rambabu, Namala,Ram, Bhavani,Dubey, Pramod Kumar,Vasudha, Bhavani,Balram, Bhavani
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p. 226 - 234
(2017/03/20)
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- Agricultural bactericide derived from gallate, and application
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The invention provides an agricultural bactericide derived from gallate, and relates to the field of agricultural medicines. The main ingredient of the agricultural bactericide is gallate derivate, wherein the gallate derivate is prepared from a compound with a structure disclosed by a formula (I) and is provided with a hydrophilic functional group-phenolic hydroxyl group. According to the agricultural bactericide prepared from the gallate derivate, various crop harmful bacteria can be inhibited, and the agricultural bactericide especially has a good bacteriostatic effect on apple altermaria leaf spot, botryosphaeria dothidea, rhizoctonia solani, colletotrichum fragariae, potato blight and the like and has good water solubility, and the problem that the gallate derivate prepared in the prior art has poor water solubility is solved.
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Paragraph 0061; 0062; 0068
(2018/01/11)
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- Synthesis method of 3,4,5-trimethoxybenzoic acid
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The invention relates to a synthesis method of 3,4,5-trimethoxybenzoic acid. Under the condition of 110 to 120 DEG C, N, N-dimethylformamide is used as a solvent; under the catalysis condition of potassium carbonate, gallic acid and dimethyl carbonate are added in one step; the 3,4,5-trimethoxybenzoic acid is synthesized through methylation. The process has the advantages that the synthesis process is simple; the cost is low; the yield reaches 95 percent or higher; the product purity reaches 100.0 percent, and the like. The green methylation reagent of dimethyl carbonate is used for replacing highly toxic dimethyl sulfate; the high risk factor of the process is overcome; the process safety is improved to the maximum degree; the economic benefits are obvious; the method is suitable for large-scale industrial production.
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Paragraph 0013-0027; 0030; 0031; 0034-0035; 0042; 0043-0045
(2017/08/29)
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- Palladium-catalyzed oxidative coupling of arylboronic acid with isocyanide to form aromatic carboxylic acids
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A valuable palladium-catalyzed oxidative coupling of aryl- and alkenyl borides with isocyanide for the synthesis of corresponding carboxylic acids has been developed. With wide substrate scopes and good functional group tolerance, this reaction offers corresponding carboxylic acids in moderate to excellent yields.
- Chen, Zhen-Bang,Liu, Kui,Zhang, Fang-Ling,Yuan, Qing,Zhu, Yong-Ming
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p. 8078 - 8083
(2017/10/10)
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- Oxidant-Controlled C-sp2/sp3-H Cross-Dehydrogenative Coupling of N-Heterocycles with Benzylamines
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Oxidant controlled ionic liquid mediated cross-dehydrogenative coupling (CDC) of benzylamines with N-heterocycles having sp2 or sp3 carbon resulted in the formation of C-benzoylated or alkenylated products. Benzoylation of N-heterocycles occurs via (NH4)2S2O8 catalyzed benzoyl radical formation. An oxidative alkenylation of N-heterocycles having C-sp3 carbon (2-methylaza-arenes) occurs via deamination of benzylamine followed by C-sp3-H bond activation in high stereoselectivity. Both benzoylation and alkenylation protocols are metal-free, green, simple, efficient, and tolerate a wide variety of functional groups.
- Sharma, Rohit,Abdullaha, Mohd,Bharate, Sandip B.
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p. 9786 - 9793
(2017/09/23)
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- DMF-mediated deprotection of bulky silyl esters under neutral and fluoride-free conditions
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Bulky TBDPS and TIPS carboxylic esters were efficiently cleaved by a green and mild protocol using only DMF-H2O (20:1) at 70 °C. The neutral conditions tolerate various common acid- and base-labile functionalities, including alkyl and aryl silyl ethers.
- Chen, Bo,Sun, Hui-Xia,Qin, Jian-Feng,Wang, Bing
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p. 253 - 255
(2016/01/12)
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- Nitrogen substitutive 3-oxygen substitutive-6-tetrahydroquinoxaline substitutive structure compound and preparation method and medical application thereof
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Disclosed are nitrogen substitutive 3-oxygen substitutive-6-tetrahydroquinoxaline substitutive structure compound and preparation method and medical application thereof. The general structure of the compound is as shown in the formula (I). The compound has tubulin polymerization inhibition activities, and is good in tumor disease resistance and proliferative disease apart from tumors.
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Paragraph 0092; 0095
(2017/01/02)
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- Catalytic Fehling's Reaction: An Efficient Aerobic Oxidation of Aldehyde Catalyzed by Copper in Water
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The first example of homogeneous copper-catalyzed aerobic oxidation of aldehydes is reported. This method utilizes atmospheric oxygen as the sole oxidant, proceeds under extremely mild aqueous conditions, and covers a wide range of various functionalized aldehydes. Chromatography is generally not necessary for product purification.
- Liu, Mingxin,Li, Chao-Jun
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supporting information
p. 10806 - 10810
(2016/09/03)
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- A Strained Disilane-Promoted Carboxylation of Organic Halides with CO2 under Transition-Metal-Free Conditions
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By using a strained four-membered ring disilane (3,4-benzo-1,1,2,2-tetraethyldisilacyclobutene) and CsF, a wide range of aryl, alkenyl, alkynyl, benzyl, allyl, and alkyl halides was successfully carboxylated under an ambient CO2 atmosphere (CO2 balloon) at room temperature within 2 h. In this carboxylation, a highly reactive silyl anion, which is generated from the disilane and CsF, is a key to facilitating the formation of a carbanion equivalent. The resulting anionic species can be trapped with CO2 to produce carboxylic acids with high efficiency.
- Mita, Tsuyoshi,Suga, Kenta,Sato, Kaori,Sato, Yoshihiro
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supporting information
p. 5276 - 5279
(2015/11/18)
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- A Metal-Free Approach to Carboxylic Acids by Oxidation of Alkyl, Aryl, or Heteroaryl Alkyl Ketones or Arylalkynes
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The metal-free oxidation of dialkyl, alkyl aryl, or alkyl heteroaryl ketones or arylalkynes to the corresponding carboxylic acids is achieved using an oxidative mixture of Oxone and trifluoroacetic acid. This green method is a simple and mild protocol to obtain carboxylic derivatives in excellent yields.
- Aravinda Kumar,Venkateswarlu, Vunnam,Vishwakarma, Ram A.,Sawant, Sanghapal D.
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p. 3161 - 3168
(2015/10/19)
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- Sulfonamide and urea-based anions chemosensors
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The detection of anions has attracted considerable interest because of their importance in various physiological processes. In this study, two sulfonamide and urea-based compounds (1a and 1b) were successfully developed and their spectroscopic and anion recognition properties were fully investigated. These results showed that: (1) compounds showed high selectivity towards cyanide and fluoride ions in CH3CN; (2) compounds only exhibited a large change in fluorescence in the presence of cyanide ions in CH3CN-H2O (95:5, v/v); and (3) compound 1b could act as a gel in dimethyl sulfoxide that transforms into a homogeneous solution upon exposure to cyanide ions. This research suggests that sulfonamide and urea can act as hydrogen-bond donors and provides an alternative approach to the design of novel anion chemosensors.
- Hu, Fang,Cao, Meijiao,Huang, Juanyun,Chen, Zhao,Wu, Di,Xu, Zhiqiang,Liu, Sheng Hua,Yin, Jun
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p. 108 - 115
(2015/04/27)
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- DMSO/I2 mediated C-C bond cleavage of α-ketoaldehydes followed by C-O bond formation: A metal-free approach for one-pot esterification
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A novel and efficient I2/DMSO mediated metal-free strategy is presented for the direct C-C bond cleavage of aryl-/heteroaryl- or aliphatic α-ketoaldehydes by C2-decarbonylation and C1-carbonyl oxidation to give the corresponding carboxylic acids followed by esterification in one pot, offering excellent yields in both the steps. Here, DMSO acts as the oxygen source/oxidant and this reaction works very well under both conventional heating and microwave irradiation. This is a very simple and convenient protocol.
- Venkateswarlu, Vunnam,Aravinda Kumar,Gupta, Sorav,Singh, Deepika,Vishwakarma, Ram A.,Sawant, Sanghapal D.
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p. 7973 - 7978
(2015/07/27)
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- ACYL-HYDRAZONE AND OXADIAZOLE COMPOUNDS, PHARMACEUTICAL COMPOSITIONS CONTAINING THE SAME AND USES THEREOF
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The present invention relates to acyl-hydrazone compounds, in particular 3,4,5-trimethoxyphenyl-hydrazide derivatives, as well as the oxadiazole analogs thereof and other similar compounds, and to the pharmaceutical use of the same for the treatment of various diseases associated with cell proliferation, such as leukemias, including acute lymphoblastic leukemia (ALL), tumours and inflammation. Acyl-hydrazones have been obtained having activity similar to that of the compound used as a standard in experiments (colchicine). The greater selectivity of the compounds according to the invention is an important feature, associated with fewer side effects than the pharmaceuticals used at present in clinical treatments. The synthetised acyl-hydrazones, more particularly the compounds 02 and 07, exhibited important antileukemic activity, which suggests 02 and 07 as candidates to pharmaceutical prototypes, or to pharmaceuticals for the treatment of leukemias, in particular acute lymphoblastic leukemia (ALL), tumours and other proliferative diseases, such as inflammation. The action mechanism of the most active compounds was determined by using DNA microarrays and subsequent tests indicated by the chip, besides selectivity studies in healthy human lymphocytes.
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Paragraph 0094; 0095; 0096
(2015/07/15)
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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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- Metal Catalyzed Oxidation of Lignin and Related Compounds
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Disclosed are methods for the benzylic oxidation of the lignin and related compounds. The methods include contacting lignin with a mixture containing manganese and iron, in the presence of oxygen to produce a carboxylic acid from lignin or a related compound. In some embodiments, the mixture includes cobalt.
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Page/Page column
(2014/09/16)
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- Electrophilicity and nucleophilicity of commonly used aldehydes
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The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
- Pratihar, Sanjay
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p. 5781 - 5788
(2014/07/22)
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- Synthesis, evaluation, and molecular docking studies of cycloalkyl/aryl-3,4,5-trimethylgallates as potent non-ulcerogenic and gastroprotective anti-inflammatory agents
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In our effort to identify the effective gastric sparing and protective anti-inflammatory agents, a series of cycloalkyl/aryl-3,4,5-trimethylgallates were synthesized and characterized. The physicochemical properties were studied to assess the lipophilicity and chemical stability. Subsequently, the compounds were evaluated for their anti-inflammatory activity and effect on gastric mucosa by most active compounds. All the compounds exhibited promising anti-inflammatory activity. In particular, 4a, 4b, 4g, and 4h emerged as the most active compounds in the series. The results of gastric mucosal studies and biochemical estimations suggested that these compounds are non-ulcerogenic and gastroprotective. The molecular docking analysis was performed to understand the binding interactions of these compounds to cyclooxygenase isoenzyme (COX-1 and COX-2). The results from this investigation suggests cycloalkyl/aryl-3,4,5- trimethylgallates as potent safer gastrosparing and protective anti-inflammatory agents.
- Dhingra, Mamta Sachdeva,Deb, Pran Kishore,Chadha, Renu,Singh, Tejvir,Karan, Maninder
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- Effect of alkoxy terminal chain length on mesomorphism of 1,6-disubstituted pyrene-based hexacatenar liquid crystals: Columnar phase control
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Synthesis and mesophase-transition behaviors of six 1,6-disubstituted pyrene-based hexacatenar liquid crystals 1n (n=8-18) are reported here. They were synthesized by the Sonogashira coupling between 1,6-diethynylpyrene and 2-bromothiophene bearing a trialkoxybenzoyl group. The phase-transition behavior was studied by differential scanning calorimetry and polarized optical microscopy; a few mesophase progressions, I-Col/I-X-Col and Col-Sm, were observed, where X was an optically isotropic but unidentified phase. The structures of Colr, Colh, and Sm phases were analyzed by the X-ray crystallography, and the effect of the terminal alkoxy chain length on the mesomorphism was evaluated.
- Hirose, Takuji,Takai, Hiroaki,Watabe, Mizuki,Minamikawa, Hiroyuki,Tachikawa, Tatsuya,Kodama, Koichi,Yasutake, Mikio
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p. 5100 - 5108
(2014/07/08)
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- Effect of alkoxy terminal chain length on mesomorphism of 1,6-disubstituted pyrene-based hexacatenar liquid crystals: Columnar phase control
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Synthesis and mesophase-transition behaviors of six 1,6-disubstituted pyrene-based hexacatenar liquid crystals 1n(n=8-18) are reported here. They were synthesized by the Sonogashira coupling between 1,6-diethynylpyrene and 2-bromothiophene bearing a trialkoxybenzoyl group. The phase-transition behavior was studied by differential scanning calorimetry and polarized optical microscopy; a few mesophase progressions, I-Col/I-X-Col and Col-Sm, were observed, where X was an optically isotropic but unidentified phase. The structures of Colr, Colh, and Sm phases were analyzed by the X-ray crystallography, and the effect of the terminal alkoxy chain length on the mesomorphism was evaluated.
- Hirose, Takuji,Takai, Hiroaki,Watabe, Mizuki,Minamikawa, Hiroyuki,Tachikawa, Tatsuya,Kodama, Koichi,Yasutake, Mikio
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p. 5100 - 5108
(2014/12/10)
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- Copper-catalyzed methyl esterification reactions via C-C bond cleavage
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The highly effective synthesis of methyl esters from benzylic alcohols, aldehydes, or acids via copper-catalyzed C-C cleavage from tert-butyl hydroperoxide is reported in this paper for the first time. Our protocol is easily accessible and practical, making it a possible supplement for the traditional way.
- Zhu, Yan,Yan, Hong,Lu, Linhua,Liu, Defu,Rong, Guangwei,Mao, Jincheng
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p. 9898 - 9905
(2013/10/22)
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- N-acylaminophenylcyclopropanes in reaction with nitrous acid generated in situ
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The reaction of N-acylaminophenylcyclopropanes with HNO2 proceeds regioselectively with introduction of an N=O fragment into the three-membered ring and formation of the corresponding Δ2-isoxazolines. For ortho-substituted N-acylaminophenylcyclopropanes side processes were observed, caused by the intramolecular participation of the N-acyl group in conversions of the carbenium ions formed on opening the cyclopropane ring under the action of the nitrosating reagent, and by direct insertion of the modified ortho substituent into the three-membered ring.
- Mochalov,Gazzaeva,Kadzhaeva,Fedotov,Trofimova
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p. 1415 - 1429
(2014/07/21)
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- Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
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Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
- Matic, Mirela,Denegri, Bernard,Kronja, Olga
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supporting information
p. 8986 - 8998,13
(2012/12/12)
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- A comparative study of different metal acetylacetonates covalently anchored onto amine functionalized silica: A study of the oxidation of aldehydes and alcohols to corresponding acids in water
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A series of metal acetylacetonates covalently anchored onto amine functionalized silica were prepared by the complexation of metal acetylacetonates [Co(acac)2, Cu(acac)2, Pd(acac) 2, Ru(acac)3, Mn(acac)3, Co(acac)3] with organically modified 3-aminopropyl silica and their catalytic activities were tested for the oxidation of aromatic aldehydes, α,β-unsaturated aldehydes and benzyl alcohols to the corresponding carboxylic acids in aqueous medium. Different metal acetylacetonates have been chosen with a view to select the most active heterogeneous catalyst for oxidations. The characterization of the catalysts was done on the basis of FTIR, TGA and AAS analysis. SiO 2-Co(acac)2 catalyzes the oxidation of aromatic aldehydes under air atmosphere without using any additional oxidant; however, t-BuOOH was found to be a highly efficient oxidant for the oxidation of α,β- unsaturated aldehydes and heterocyclic aldehydes, as well as the direct oxidation of benzyl alcohols to the corresponding carboxylic acids. The most active catalyst was found to be highly stable and recyclable under the reaction conditions. The Royal Society of Chemistry.
- Sodhi, Ravinderpal Kour,Paul, Satya,Clark
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p. 1649 - 1656
(2013/02/22)
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- Solvent-free oxidation of aldehydes to acids by TBHP using environmental-friendly MnO-14-exchanged Mg-Al hydrotalcite catalyst
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A number of hydrotalcite (Mg-Al, Mn-Al, Co-Al, Ni-Al, Mg-Fe, Mg-Cr and Cu-Al) catalysts, with or without MnO-14-exchange, were evaluated for their performance in the solvent-free oxidation of benzaldehyde to benzoic acid by tert-butyl hydroperoxide under reflux in the absence of any solvent. The MnO-14 - exchanged Mg-Al-hydrotalcite (Mg/Al = 10) showed high activity in the oxidation of different aromatic and aliphatic aldehydes to their corresponding acids and also showed excellent reusability in the oxidation process which is environmental-friendly. Indian Academy of Sciences.
- Choudhary, Vasant R.,Dumbre, Deepa K.,Narkhede, Vijay S.
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p. 835 - 839
(2012/11/13)
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