- Switchable columnar metallomesogens. New helical self-assembling systems
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Chiral oxovanadium(IV), copper(II), and palladium(II) β-diketonates show a room-temperature columnar mesophase which undergoes ferroelectric switching. All the compounds were obtained as liquid crystals at room temperature, and crystallization or melting processes were not detected by differential scanning calorimetry carried out to -20 °C. The mesophase was investigated by optical microscopy, DSC and X-ray diffraction, and identified as a rectangular columnar (P21). The flower like texture observed for all the compounds led us to deduce a high tilt angle (ca. 40°) of the molecules with respect to the column axis. Circular dichroism has confirmed the existence of a helical arrangement within the column. This result is in accordance with the so-called columnar mode found at low frequencies (ca. 10-3 Hz) in dielectric spectroscopy studies electrooptical response of these materials has been examined by means of a photomultiplier. The results obtained can be explained by considering a strong influence of the high tilt angle found in the mesophase.
- Barberá,Iglesias,Serrano,Sierra,De La Fuente,Palacios,Pérez-Jubindo,Vázquez
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Read Online
- Preparation and Characterization of Tetraaza[14]annulene and its Nickel(II) and Copper(II) Complexes with Crown Ether Functionalities
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Three new organic hosts are described that contain a tetraaza[14]annulene core to which two crown ether voids are attached. These hosts include a free base tetraaza[14]annulene and/or its complexes with benzo-15-crown-5 rings. The crown tetraaza[14]annulene is synthesized from tetraaza[14]annulene and 4′-chloroformylbenzo-15-crown-5. Its nickel(II) and copper(II) complexes are prepared in a similar manner as above. In solution the compounds do not tend to form aggregates. However, aggregation is affected by the presence of alkali-metal salts, which coordinate to the crowns. Li+ and Na+ cations with diameters that match the diameters of the crown ether rings form 1:2 host-guest complexes. Complexes with 2:2 host-guest stoichiometry are formed when the diameters of K+ and Cs+ cations exceed that of the crown ether rings. Nevertheless, it is weak for the present macrocycle and its complexes to be inclined to form dimers owing to the steric hindrance of the substituent groups and owing to restraining the rotation of the carbonyl bond connecting the crown ether group.
- Sakata, Kazunori,Shimoda, Manabu,Hashimoto, Mamoru
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Read Online
- Iron-catalyzed arene C-H hydroxylation
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The sustainable, undirected, and selective catalytic hydroxylation of arenes remains an ongoing research challenge because of the relative inertness of aryl carbon-hydrogen bonds, the higher reactivity of the phenolic products leading to over-oxidized by-products, and the frequently insufficient regioselectivity. We report that iron coordinated by a bioinspired L-cystine-derived ligand can catalyze undirected arene carbon-hydrogen hydroxylation with hydrogen peroxide as the terminal oxidant. The reaction is distinguished by its broad substrate scope, excellent selectivity, and good yields, and it showcases compatibility with oxidation-sensitive functional groups, such as alcohols, polyphenols, aldehydes, and even a boronic acid. This method is well suited for the synthesis of polyphenols through multiple carbon-hydrogen hydroxylations, as well as the late-stage functionalization of natural products and drug molecules.
- Cheng, Lu,Wang, Huihui,Cai, Hengrui,Zhang, Jie,Gong, Xu,Han, Wei
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- Iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabled aldehyde C-H methylation
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A practical and general iron-catalyzed domino decarboxylation-oxidation of α,β-unsaturated carboxylic acids enabling aldehyde C-H methylation for the synthesis of methyl ketones has been developed. This mild, operationally simple method uses ambient air as the sole oxidant and tolerates sensitive functional groups for the late-stage functionalization of complex natural-product-derived and polyfunctionalized molecules.
- Gong, Pei-Xue,Xu, Fangning,Cheng, Lu,Gong, Xu,Zhang, Jie,Gu, Wei-Jin,Han, Wei
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p. 5905 - 5908
(2021/06/18)
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- Electrochemical reactivity of S-phenacyl-O-ethyl-xanthates in hydroalcoholic (MeOH/H2O 4:1) and anhydrous acetonitrile media
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The electrochemical behavior of a series of S-phenacyl-O-ethyl-xanthates (O-ethyl-dithiocarbonate acetophenone derivatives) in hydroalcoholic (MeOH/H2O 4:1) and anhydrous media (ACN/TBAPF6) using carbon electrodes was studied. Cyclic voltammetry showed in hydroalcoholic media only two cathodic waves, whereas in ACN one anodic and two cathodic waves were present. The first cathodic wave corresponded to the reduction of the phenylketone group, whereas the first anodic was attributed to the xanthate unit. Macroelectrolysis on graphite and vitreous carbon at anodic and cathodic potentials, let us to explore the synthetic potential of this electrochemical reactions. With some compounds in hydroalcoholic media and using carbon electrodes, polymeric material was deposited on the electrode impeding the reaction; this deposit was characterized by AFM and SEM-EDS. The electroreduction on Ti electrode overcome this problem and gave the corresponding acetophenones (>95%). On the other hand, in ACN, small quantities of the dimeric 1,4-dicarbonyl compounds X-PhCOCH2CH2COPh-X (7–15%), as well as the corresponding acetophenones (ca. 50%) were isolated. Oxidation macroelectrolysis showed a very complicated transformation without synthetic value. The reaction mechanism for the reduction and the homolytic dissociation into the phenacyl radical was supported by DFT calculations.
- López-López, Ernesto Emmanuel,López-Jiménez, Sergio J.,Barroso-Flores, Joaquín,Rodríguez-Cárdenas, Esdrey,Tapia-Tapia, Melina,López-Téllez, Gustavo,Miranda, Luis D.,Frontana-Uribe, Bernardo A.
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- Thiols Act as Methyl Traps in the Biocatalytic Demethylation of Guaiacol Derivatives
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Demethylating methyl phenyl ethers is challenging, especially when the products are catechol derivatives prone to follow-up reactions. For biocatalytic demethylation, monooxygenases have previously been described requiring molecular oxygen which may cause oxidative side reactions. Here we show that such compounds can be demethylated anaerobically by using cobalamin-dependent methyltransferases exploiting thiols like ethyl 3-mercaptopropionate as a methyl trap. Using just two equivalents of this reagent, a broad spectrum of substituted guaiacol derivatives were demethylated, with conversions mostly above 90 %. This strategy was used to prepare the highly valuable antioxidant hydroxytyrosol on a one-gram scale in 97 % isolated yield.
- Grimm, Christopher,Kroutil, Wolfgang,Pompei, Simona,Schiller, Christine,Schober, Lukas
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supporting information
p. 16906 - 16910
(2021/07/02)
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- Anchimerically Assisted Selective Cleavage of Acid-Labile Aryl Alkyl Ethers by Aluminum Triiodide and N, N-Dimethylformamide Dimethyl Acetal
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Aluminum triiodide is harnessed by N,N-dimethylformamide dimethyl acetal (DMF-DMA) for the selective cleavage of ethers via neighboring group participation. Various acid-labile functional groups, including carboxylate, allyl, tert-butyldimethylsilyl (TBS), and tert-butoxycarbonyl (Boc), suffer the conditions intact. The method offers an efficient approach to cleaving catechol monoalkyl ethers and to uncovering phenols from acetal-type protecting groups such as methoxymethyl (MOM), methoxyethoxymethyl (MEM), and tetrahydropyranyl (THP) chemoselectively.
- Sang, Dayong,Yue, Huaxin,Zhao, Zhengdong,Yang, Pengtao,Tian, Juan
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p. 6429 - 6440
(2020/07/14)
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- Selective ether bond breaking method of aryl alkyl ether
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The invention discloses a selective aryl alkyl ether cracking method, which comprises that aryl alkyl ether, aluminum iodide and an additive are subjected to a selective ether bond cleavage reaction in an organic solvent at a temperature of -20 DEG C to a reflux temperature to generate phenol and derivatives thereof. The method is mild in condition and simple and convenient to operate, is suitablefor cracking aryl alkyl ether containing o-hydroxyl and o-carbonyl and acetal ether, and can also be used for removing tertiary carbon hydroxyl protecting groups with higher steric hindrance, such astriphenylmethyl, tertiary butyl and the like.
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Paragraph 0153-0155
(2020/09/16)
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- Design, synthesis and evaluation of diaryl γ-dihydropyrone derivatives as cyclocurcumin mimetics and inhibitors of the aggregation of amyloid β
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A structure activity relationship study of cyclocurcumin-derived, diaryl γ-dihydropyrone-based inhibitors of amyloid β aggregation is described. Optimization of the diaryl γ-dihydropyrone framework and two phenolic rings resulted in the identification of diaryl γ-dihydropyrone type cyclocurcumin analogue AY1511, which exhibited potent anti-amyloid β aggregation activity (leading to nanorod-like fragments), sufficient water solubility, and low cytotoxicity.
- Hotsumi, Mayumi,Tajiri, Misato,Makabe, Koki,Konno, Hiroyuki
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supporting information
(2020/10/06)
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- A convenient synthetic approach to dioncoquinone B and related compounds
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A total synthesis of dioncoquinone B and related compounds, including ancistroquinones B, C and malvon A, is presented. The strategy is based on available reagents and can be used as a preparative synthesis of a number of natural and synthetic biologically active (3-alkyl)-2,7,8-di(tri)methoxy(hydroxy)-1,4-naphthoquinones.
- Khmelevskaya, Ekaterina A.,Pelageev, Dmitry N.
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supporting information
p. 1022 - 1024
(2019/03/13)
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- Cleavage of Catechol Monoalkyl Ethers by Aluminum Triiodide-Dimethyl Sulfoxide
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Using eugenol and vanillin as model substrates, a practical method is developed for the cleavage o -hydroxyphenyl alkyl ethers. Aluminum oxide iodide (O=AlI), generated in situ from aluminum triiodide and dimethyl sulfoxide, is the reactive ether cleaving species. The method is applicable to catechol monoalkyl ethers as well as normal phenyl alkyl ethers for the removal of methyl, ethyl, isopropyl, and benzyl groups. A variety of functional groups such as alkenyl, allyl, amide, cyano, formyl, keto, nitro, and halogen are well tolerated under the optimum conditions. Partial hydrodebromination was observed during the demethylation of 4-bromoguaiacol, and was resolved using excess DMSO as an acid scavenger. This convenient and efficient procedure would be a practical tool for the preparation of catechols.
- Sang, Dayong,Tian, Juan,Tu, Xiaodong,He, Zhoujun,Yao, Ming
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p. 704 - 712
(2019/01/23)
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- Formation of Phenolic Compounds from d -Galacturonic Acid
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Aqueous d-galacturonic acid (d-GalA) model systems treated at 130 °C at different pH values show an intense color formation, whereas other reducing sugars, such as d-galactose (d-Gal), scarcely react. GC-MS measurements revealed the presence of several ph
- Urbisch, Alexandra,Einhorn-Stoll, Ulrike,Kastner, Hanna,Drusch, Stephan,Kroh, Lothar W.
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- Ether bond dissociation method of phenylalkyl ether
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The invention discloses an ether bond dissociation method of phenylalkyl ether. The ether bond dissociation method of phenylalkyl ether includes the following steps that in organic solvent, in the presence of aluminium trihalogen, metal iodide and acid scavenging agents, phenylalkyl ether is subjected to an ether bond dissociation reaction at -20 DEG C to reflux temperature to generate phenol andderivatives thereof. The ether bond dissociation method of phenylalkyl ether is mild in condition, convenient to operate, high in yield and wide in phenylalkyl ether applicable range.
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Paragraph 0074; 0075; 0076; 0080-0082
(2018/09/29)
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- Ether bond cracking method of phenylalkyl ether
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The invention discloses an ether bond cracking method of phenylalkyl ether. The method comprises the following steps: performing ether bond breaking reaction on phenylalkyl ether at -20 to reflux temperature in the presence of aluminium triiodide and dimethyl sulfoxide, thereby generating phenol and derivatives thereof. The method disclosed by the invention is mild in condition, simple and convenient for operation, high in yield, and extensive in applicable phenylalkyl ether range.
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Paragraph 0155-0157
(2018/11/26)
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- A phenyl alkyl ether ether linkage breaking method (by machine translation)
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The invention discloses a phenyl alkyl ether ether linkage breaking method, the method is: in the organic solvent, in the presence of a mineral acid and the aluminium triiodide scavenging agent under the conditions of, phenyl ether in the - 20 °C to reflux temperature lower ether linkage breaking reaction, generating phenol and its derivatives. The mild conditions, the operation is simple, and the yield is high, the applicable phenyl ether range is wide. (by machine translation)
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Paragraph 0061-0063
(2018/04/01)
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- Pyridine Improves Aluminum Triiodide Induced Selective Cleavage of Alkyl o -Hydroxyphenyl Ethers: A Practical and Efficient Procedure for the Preparation of Hydroxychavicol by Demethylation of Eugenol
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Demethylation of eugenol with aluminum triiodide is complicated by an unexpected hydrogenation side reaction. The hydrogenation proceeds through a cascade deprotonation, hydroiodination, and hydrogen-halogen exchange process, and can be prevented by suppressing the hydroiodination in advance. A practical demethylation procedure is thus developed that delivers hydryoxychavicol in essentially quantitative yield by using pyridine as an additive. The method is selective towards cleaving alkyl o-hydroxyphenyl ethers and is compatible with a variety of functional groups.
- Sang, Dayong,Yao, Ming,Tian, Juan,Chen, Xiaoman,Li, Li,Zhan, Hongju,You, Linhong
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p. 138 - 142
(2016/12/26)
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- Carbodiimides as Acid Scavengers in Aluminum Triiodide Induced Cleavage of Alkyl Aryl Ethers
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A practical procedure for the cleavage of alkyl aryl ethers containing labile functional groups has been developed using aluminum triiodide as the ether cleaving reagent. Carbodiimides, typically used as dehydration reagents for the coupling of amines and carboxylic acids to yield amide bonds, are found to be effective hydrogen iodide scavengers that prevent acid-labile groups from deterioration. The method is applicable to variant alkyl aryl ethers such as eugenol, vanillin, ortho -vanillin and methyl eugenol. Suitable substrates are not limited to alkyl o -hydroxyphenyl ethers.
- Sang, Dayong,Wang, Jiahui,Zheng, Yun,He, Jianyuan,Yuan, Caili,An, Qing,Tian, Juan
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p. 2721 - 2726
(2017/06/13)
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- Ether bond breakage method for phenylalkyl ethers
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The invention discloses an ether bond breakage method for phenylalkyl ethers. The method comprises the step: subjecting the phenylalkyl ethers to an ether bond breakage reaction at the temperature of -20 DEG C to reflux temperature in an organic solvent in the presence of aluminum triiodide and carbodiimide, so as to produce phenols and derivatives thereof. The method is moderate in conditions, simple and convenient in operation, high in yield and wide in applicable phenylalkyl ether range.
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Paragraph 0107-0109
(2017/07/19)
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- Synthesis method of efloxate drug intermediate 3, 4-dihydroxyacetophenone
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The invention relates to a synthesis method of efloxate drug intermediate 3, 4-dihydroxyacetophenone. The method comprises the following steps: feeding 380-390ml of dimethylamine, 1.1mol of cuprous chloride and 0.34mol of catechol into a reaction vessel provided with a stirrer, a reflux condenser, a temperature gauge and a dropping funnel, controlling the stirring speed to be 130-160 rpm, and stirring for 60-90 minutes; heating the mixed solution up to 60-70 DEG C, and carrying out a reaction for 2-3 hours; slowly feeding 0.35-0.37mol of acetamide into the reaction vessel, carrying out a reflux reaction for 3-4 hours, and then distilling to remove the dimethylamine; heating the obtained solution up to 150-160 DEG C, carrying out a reaction for 3-4 hours, pouring out the reaction solution while the solution is hot, cooling and curing to obtain a brown solid; dissolving the brown solid by 1.5L of phosphoric acid solution, extracting the dissolved substance for 3-6 times by hexane, blending the extracted solution, washing the product by salt solution, carrying dehydration by a dehydrating agent, carrying out reduced pressure distillation to remove the hexane, cooling the solution to 5-minus 8 DEG C, filtering, and drying; carrying out recrystallization on the product in acetonitrile, decoloring by a molecular sieve, cooling the solution to 2-3 DEG C, separating out crystal, filtering, washing by isopropyl alcohol, and drying to obtain the 3, 4-dihydroxyacetophenone.
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Paragraph 0015-0016
(2017/02/28)
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- Divergent and concise total syntheses of dihydrochalcones and 5-deoxyflavones recently isolated from Tacca species and Mimosa diplotricha
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Dihydrochalcones and 5-deoxyflavones are types of compounds possessing various biologically interesting properties. Herein, we report the concise and divergent total syntheses of several naturally occurring dihydrochalcones and 5-deoxyflavones from readily available starting materials. The divergent strategy is based around manipulation of a common chalcone scaffold and features application of Algar-Flynn-Oyamada oxidation and benzoquinone C-H activation methodologies. These are the first reported total syntheses of these biologically interesting compounds and the concise and flexible route should be readily amenable to future analogue generation. Furthermore, this work provides an illustration of the utility of divergent synthesis for the expedient and step-economical preparation of natural product libraries.
- Sum, Tze Han,Sum, Tze Jing,Stokes, Jamie E.,Galloway, Warren R.J.D.,Spring, David R.
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p. 4557 - 4564
(2015/06/08)
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- Selective acylation of phenols in boron trifluoride diethyl etherate solution and the mechanistic implication
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In the presence of boron trifluoride diethyl etherate (BF3 · OEt2), direct acylation of phenols with free carboxylic acid is chemoselective and regioselective and no demethylation, if any, was observed. The para-directing effect of BF3·OEt2 is attributed to the large steric hindrance of the boron trifluoride-phenolic hydroxyl group complex, which blocks the ortho-acylation from occurrence. Microwave irradiation could not change the regioselectivity of BF3·OEt2 except the reaction time being greatly shortened.
- Xiao, Zhu-Ping,Wei, Wei,Huang, Shen,Lin, Xiao-Yi,Peng, Bin,Wang, Xu-Dong,Zhang, Lei
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p. 8039 - 8042
(2015/02/02)
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- Analogs of anthocyanins with a 3′,4′-dihydroxy substitution: Synthesis and investigation of their acid-base, hydration, metal binding and hydrogen-donating properties in aqueous solution
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Glycosides of hydroxylated flavylium ions are proposed as pertinent analogs of anthocyanins, a major class of polyphenolic plant pigments. Anthocyanins with a 3′,4′-dihydroxy substitution on the B-ring (catechol nucleus) are especially important for their metal chelating and electron-donating (antioxidant) capacities. In this work, an efficient chemical synthesis of 3′,4′-dihydroxy-7-O-β-d-glucopyranosyloxyflavylium chloride and its aglycone is reported. Then, the ability of the two pigments to undergo proton transfer (formation of colored quinonoid bases) and add water (formation of a colorless chalcone) is investigated: at equilibrium the colored quinonoid bases (kinetic products) are present in very minor concentrations (3+, the Al3+-glucoside complex is more stable than the Al3+-aglycone complex due to the higher sensitivity of the latter to water addition and conversion into the corresponding chalcone. Finally, the glucopyranosyloxyflavylium ion and its aglycone are compared for their ability to reduce the 1,1-diphenyl-2-picrylhydrazyl radical in a mildly acidic water/MeOH (1:1) mixture as a first evaluation of their antioxidant activity. Glycosidation at C7-OH results in a lower rate constant of first electron transfer to DPPH and a lower stoichiometry (total number of 1,1-diphenyl-2-picrylhydrazyl radicals reduced per pigment molecule). Anthocyanins are difficult to extract from plants in substantial amount. However, the analogs investigated in this work are of easy access by chemical synthesis and express the physico-chemical properties typical of anthocyanins. They can thus be regarded as valuable models for investigating the coloring, metal-binding and antioxidant properties of these important natural pigments.
- Mora-Soumille, Nathalie,Al Bittar, Sheiraz,Rosa, Maxence,Dangles, Olivier
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- An efficient strategy for protecting dihydroxyl groups of catechols
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A novel strategy for protecting dihydroxyl groups of catechols has been developed. Base-mediated cyclizations of catechols with 1,3-dibromopropane provided the corresponding benzo[b]1,4-dioxepans, and herefrom the protecting group was easily cleaved by aluminum chloride. The preparation of the antibacterial and antifungal agent 4-(2-aminothiazol-4-yl)benzene-1,2-diol from catechol reliably verified its availability amenable to various harsh reaction conditions. Georg Thieme Verlag Stuttgart - New York.
- Huang, Wei-Bin,Guo, Ying,Jiang, Jian-An,Pan, Xian-Dao,Liao, Dao-Hua,Ji, Ya-Fei
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supporting information
p. 741 - 746
(2013/05/09)
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- Elucidation of Mycobacterium tuberculosis TypeII Dehydroquinase Inhibitors using a Fragment Elaboration Strategy
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A library of novel Mycobacterium tuberculosis typeII dehydroquinase (DHQase) inhibitors were discovered through the use of a fragment elaboration approach. Putative active site binding fragments were initially assessed insilico which led to the selection of two small aromatic fragments for further investigation. Synthetic elaboration of the fragments provided a library of 34 inhibitors that exhibited low-micromolar inhibition of typeII DHQase. A number of these inhibitors also showed antibacterial activity in the low-micromolar range in screens against M. tuberculosis invitro; these now serve as lead compounds for further development of therapeutics for the treatment of tuberculosis.
- Tran, Anh Thu,West, Nicholas P.,Britton, Warwick J.,Payne, Richard J.
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experimental part
p. 1031 - 1043
(2012/07/31)
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- Unichiral 2-(2′-pyrrolidinyl)-1,4-benzodioxanes: The 2 R,2′ S diastereomer of the N -methyl-7-hydroxy analogue is a potent α4β2- and α6β2-nicotinic acetylcholine receptor partial agonist
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A series of unichiral 7-substituted 2-(1′-methyl-2′- pyrrolidinyl)-1,4-benzodioxanes were synthesized and tested for the affinity for the α4β2 and α7 central nicotinic receptors; the 2R,2′S diastereomer of the 7-OH analogue [(R,S)-7], unique in the series, has a high α4β2 affinity (12nM Ki). N-Demethylation and configuration inversion of the stereocenters greatly weaken its α4β2 affinity, confirming that such a rigid molecule can be considered a new template for α4β2 ligands. Docking analysis showed how (R,S)-7 is capable of strongly and specifically interacting with the amino acidic counterpart of the α4β2 receptor binding site. Further pharmacological characterization demonstrated that (R,S)-7 also has a high affinity for the α6β2 receptor, and in vitro functional tests indicated that it is a potent α4β2 and α6β2 partial agonist, with modest affinity and potency for the α3β4 receptor. Comparison with varenicline, a well-known nicotinic partial agonist used as a smoking cessation aid, interestingly reveals similar nicotinoid profiles.
- Bolchi, Cristiano,Gotti, Cecilia,Binda, Matteo,Fumagalli, Laura,Pucci, Luca,Pistillo, Francesco,Vistoli, Giulio,Valoti, Ermanno,Pallavicini, Marco
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supporting information; experimental part
p. 7588 - 7601
(2012/01/05)
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- Synthesis of catechols from phenols via Pd-catalyzed silanol-directed C-H oxygenation
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A silanol-directed, Pd-catalyzed C-H oxygenation of phenols into catechols is presented. This method is highly site selective and general, as it allows for oxygenation of not only electron-neutral but also electron-poor phenols. This method operates via a silanol-directed acetoxylation, followed by a subsequent acid-catalyzed cyclization reaction into a cyclic silicon-protected catechol. A routine desilylation of the silacyle with TBAF uncovers the catechol product.
- Huang, Chunhui,Ghavtadze, Nugzar,Chattopadhyay, Buddhadeb,Gevorgyan, Vladimir
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p. 17630 - 17633
(2011/12/16)
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- The synthesis, structure and activity evaluation of pyrogallol and catechol derivatives as Helicobacter pylori urease inhibitors
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Some pyrogallol and catechol derivatives were synthesized, and their urease inhibitory activity was evaluated by using acetohydroxamic acid (AHA), a well known Helicobacter pylori urease inhibitor, as positive control. The assay results indicate that many compounds have showed potential inhibitory activity against H. pylori urease. 4-(4-Hydroxyphenethyl)phen-1,2-diol (2a) was found to be the most potent urease inhibitor with IC50s of 1.5 ± 0.2 μM for extracted fraction and 4.2 ± 0.3 μM for intact cell, at least 10 times and 20 times lower than those of AHA (IC50 of 17.2 ± 0.9 μM, 100.6 ± 13 μM), respectively. This finding indicate that 2a would be a potential urease inhibitor deserves further research. Molecular dockings of 2a into H. pylori urease active site were performed for understanding the good activity observed.
- Xiao, Zhu-Ping,Ma, Tao-Wu,Fu, Wei-Chang,Peng, Xiao-Chun,Zhang, Ai-Hua,Zhu, Hai-Liang
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experimental part
p. 5064 - 5070
(2010/12/24)
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- Studies towards the synthesis of 13C-labelled anthocyanins
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The anthocyanins are a class of polyphenols found in nature, which are widely distributed throughout the plant kingdom and are thought to possess antioxidant properties. Methodology previously developed in our group for the regioselective placement of 13C-atoms into aromatic rings is being applied to the synthesis of 13C-labelled anthocyanins-namely cyanidin-3-glucoside and delphinidin-3-glucoside. Copyright
- Marshall, Laura J.,Cable, Karl M.,Botting, Nigel P.
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scheme or table
p. 315 - 318
(2011/05/02)
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- Polyphenols based on isoflavones as inhibitors of Helicobacter pylori urease
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Twenty polyphenols were synthesized and evaluated for their effect on Helicobacter pylori urease. Among these compounds, 4-(p-hydroxyphenethyl)pyrogallol (15) (IC50 = 0.03 mM) and 7,8,4′-trihydroxyisoflavone (19) (IC50 = 0.14 mM) showed potent inhibitory activities, and inhibited Helicobacter pylori urease in a time-dependent manner. The structure-activity relationship of these polyphenols revealed: the two ortho hydroxyl groups were essential for inhibitory activity of polyphenol. When the C-ring of isoflavone was broken, the inhibitory activity markedly decreased. As for deoxybenzoin, the carboxyl group was clearly detrimental.
- Xiao, Zhu-Ping,Shi, Da-Hua,Li, Huan-Qiu,Zhang, Li-Na,Xu, Chen,Zhu, Hai-Liang
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p. 3703 - 3710
(2008/02/07)
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- The immobilized porphyrin-mediator system Mn(TMePyP)/clay/HBT (clay-PMS): A lignin peroxidase biomimetic catalyst in the oxidation of lignin and lignin model compounds
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A biomimetic system for lignin peroxidase (LiP) was designed by using a cationic porphyrin, [Mn(TMePyP)OAc5], supported on the smectitic clay montmorillonite [Mn(TMe-PyP)/clay]. The natural role of the polypeptidic pocket of LiP was mimicked by the clay. The possibility to use low-molecular-weight redox mediators as active readily diffusible oxidizing species has been investigated. This assembly - a sort of "synthetic enzyme" - can be defined as an immobilized porphyrin-mediator system (clay-PMS). The clay-PMS was found to be a stable, recyclable, and efficient catalyst for the environmentally friendly H2O2-catalyzed oxidation of different lignins and representative lignin model compounds. The clay-PMS showed a higher reactivity than Mn(TMePyP)/clay alone due to an effective role of the redox mediator on the oxidation. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Crestini, Claudia,Pastorini, Alessandra,Tagliatesta, Pietro
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p. 4477 - 4483
(2007/10/03)
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- A new and convenient one-step synthesis of the natural 3-deoxyanthocyanidins apigeninidin and luteolinidin chlorides from 2,4,6-triacetoxybenzaldehyde
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The total synthesis of apigeninidin (1), luteolinidin (2) and 5,7-dihydroxyflavylium (5) chlorides is performed through a one step reaction from an acetylated derivative of a commercial reagent. Condensation reaction between 2,4,6-triacetoxybenzaldehyde and an acetophenone derivative in anhyd methanolic hydrogen chloride provides the 3-deoxyanthocyanidins in high yields.
- Mas, Thierry
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p. 1878 - 1880
(2007/10/03)
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- Zinc Mediated Friedel-Crafts Acylation in Solvent-Free Conditions under Microwave Irradiation
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Zn powder is found to catalyze the Friedel-Crafts acylation of aromatic compounds with acyl halides efficiently under microwave irradiation in solvent-free conditions. Activated substrates undergo acylation predominantly at the para-position. The Zn powder can be re-used up to six times after simple washing with diethyl ether and dilute HCl.
- Paul, Satya,Nanda, Puja,Gupta, Rajive,Loupy, Andre
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p. 2877 - 2881
(2007/10/03)
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- Nitration and hydroxylation of substituted phenols by peroxynitrite. Kinetic feature and an alternative mechanistic view
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The reaction of peroxynitrite (ONOO-) with a series of para-substituted phenols has been examined in aqueous phosphate buffer and acetonitrile solutions. Major products were the corresponding 2-nitro derivative and the 4-substituted catechol. Kinetic study showed good correlation with Hammett σ(p)+ parameters and reduction potentials, suggesting the possible one-electron transfer process involving the nitrosoniun ion (NO+) as initial electrophile generated from peroxynitrous acid.
- Nonoyama, Nobuaki,Chiba, Kazuhiko,Hisatome, Kaori,Suzuki, Hitomi,Shintani, Futoshi
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p. 6933 - 6937
(2007/10/03)
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- Benzoxazine derivatives, methods for obtaining same, and their use as drugs
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Compounds are provided corresponding to the following general formula (I): in which:--R1 and R2, independently of each other, represent an alkyl group with 1 to 3 carbon atoms, or a group of formula --CH2 --ORa, Ra representing a hydrogen atom or a methyl group Rx represents: an alkyl group with 1 to 3 carbon atoms, in particular a methyl group, or an --ORx1 group, Rx1 representing an alkyl group with 1 to 3 carbon atoms, in particular a methoxy group, or a group of formula --CH2 --X in which X represents a halogen atom, in particular chlorine, or a group of formula (a) STR1 in which: R3 and R5, independently of each other, represent a hydrogen atom, or an --OH group, or an --OCH3 group, R4 represents a hydrogen atom, or an --ORb group, Rb representing a hydrogen atom or a methyl group, or R4 represents a group of formula --Orc, Rc representing a group of formula --CH2 --CO--C6 H4 R'. The present compounds are benzoxazine derivatives which are used for treating pathological conditions associated with the presence of free radicals, such as Alzheimer's disease, and methods are provided for preparation of these compounds.
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- Anthocyanin-aluminium and -gallium complexes in aqueous solution
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Complexation of aluminium and gallium ions with synthetic anthocyanin models and natural anthocyanins extracted from the blue flowers of Evolvulus pilosus cv 'Blue Daze' and the violet flowers of Matthiola incana has been thoroughly investigated in aqueous solution. From UV-VIS spectroscopic data collected at pH 2-5, the presence of complexes, involving not only the coloured forms but also the colourless forms of the pigments is demonstrated. A theoretical treatment is developed for the calculation of the corresponding stability constants. The pigments studied throughout this work can be divided into two series, one sharing a cyanidin chromophore and the other a delphinidin one. Within both series, individual pigments are distinguished according to the degree and type of glycosylation and/or acylation. Intramolecular effects such as copigmentation of anthocyanin-aluminium complexes and the effect of the presence of a malonyl group on the formation of those complexes are discussed. These results are important to plant pigmentation and, for instance, a narrow pH domain in which colour amplification due to complexation is at a maximum has been found.
- Elhabiri,Figueiredo,Toki,Saito,Brouillard
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p. 355 - 362
(2007/10/03)
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- Regioselective hydrolysis of polyacetoxy aromatic ketones with lipases in organic solvents
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Lipases from porcine pancreas (PPL) and Candida cylindracea (CCL) have been used for deacetylation of polyacetoxy aromatic ketones in organic solvents.A systematic study has been made to establish regioselectivity, effect of the nature of solvents and role of steric bulk on hydrolysable groups.High regioselectivity and effect of nature of solvents on the rate of the reactions have been observed.
- Parmar, V S,Khanduri, C H,Tyagi, O D,Prasad, A K,Gupta, Suman,et al.
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p. 925 - 929
(2007/10/02)
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- Reaction of Acetic Anhydride/Zinc Chloride Reagent with Phenols: Improved Yields of Hydroxyacetophenones
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Acetic anhydride/zinc chloride has been found to be a better acylating system for phenol and polyphenols resulting in improved yields of the respective hydroxyacetophenones.The phenols used are phenol, resorcinol, hydroquinonone, catechol, phloroglucinol and pyrogallol.With resorcinol the isomeric diacetyl derivatives are formed in excellent yields in a single step, while catechol and hydroquinone give only monoacetyl derivatives like simple phenol.Pyrogallol gives a monoacetyl derivative while phloroglucinol gives both mono and diacetyl derivatives but not triacetyl derivatives.
- Anjaneyulu, A. S. R.,Mallavadhani, U. V.,Venkateswarlu, Y.,Prasad, A. V. Rama
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p. 823 - 826
(2007/10/02)
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- Synthesis of Urushiol Derivatives by the Fries Rearrangement
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The photo- and thermal-induced Fries rearrangement reactions of some unsaturated aliphatic esters of benzene-1,2-diol (catechol) have been studied.Photorearrangement and thermal rearrangement favoured products correspond to ortho and para migration respectively, but the thermal rearrangement may be acompanied by indanones, chromanones and other products which were formed through subsequent side reactions of the double bond.Photoinduced Fries rearrangement of 2-hydroxyphenyl oleate followed by reduction of the carbonyl group gave monosubstituted catechol derivatives with an unsaturated C18 side chain in either the 3- or 4-position.These alkenylcatechol derivatives are related in structure to chemical components isolated from oriental lacquer trees, such as urushiol from Rhus verniciflua or thitsiol from Melanorrhoea usitata
- Jefferson, Alan,Wangchareontrakul, Sirichai
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p. 605 - 614
(2007/10/02)
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- Formation of Aromatic Compounds from Carbohydrates. VIII. Reaction of D-Erythrose in Slightly Acidic, Aqueous Solution
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The title reaction yielded 5-hydroxymethylfuran-2-carboxaldehyde (1), 1--ethanone (2), 1,2-benzenediol (3), 3-methyl-1,2-benzenediol (4), 3,4-dihydroxybenzaldehyde (5), 3,4-dihydroxybenzoic acid (6), (3,4-dihydroxyphenyl)-1-ethanone (7), formic (8), hydroxyacetic (9), 3-hydroxypropanoic acid (10), and hydroxyacetaldehyde (11).Compound 2 was not previously been identified in degradation products of carbohydrates.
- Theander, Olof,Westerlund, Eric
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p. 701 - 706
(2007/10/02)
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- Benzodioxincarboxamides
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Certain 2,3-dihydro-1,4-benzodioxin-2-carboxamides, useful as lipogenesis inhibitors in mammals.
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