- Fluorine-containing substituents: Metabolism of the α,α-difluoroethyl thioether motif
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We report the metabolism of the recently introduced α,α-difluoroethyl thioether motif to explore further its potential as a substituent for bioactives discovery chemistry. Incubation of two aryl-SCF2CH3 ethers with the model yeast organism Cunninghamella elegans, indicates that the sulfur of the thioether is rapidly converted to the corresponding sulfoxide, and then significantly more slowly to the sulfone. When the substrate was (p-OMe)PhSCF2CH3, then the resultant (demethylated) phenol sulfoxide had an enantiomeric excess of 60%, and when the substrate was the β-substituted-SCF2CH3 naphthalene, then the enantiomeric excess of the resultant sulfoxide was 54%. There was no evidence of defluorination, unlike the corresponding oxygen ether (p-OMe)PhOCF2CH3, which was converted to the (demethylated) phenol acetate ester during C. elegans incubation. We conclude that the aryl-S-CF2CH3 motif is metabolised in a similar manner to aryl-SCF3, a motif that is being widely explored in discovery chemistry. It is however, significantly less lipophilic than aryl-SCF3 which may offer a practical advantage in tuning overall phar-macokinetic profiles of molecules in development.
- Rodil, Andrea,Slawin, Alexandra M.Z.,Al-Maharik, Nawaf,Tomita, Ren,O'Hagan, David
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Read Online
- Synthetic approach to the functionalized tricyclic core of atropurpuran
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A strategy for synthesizing the tricyclic fragment 5 of atropurpuran 1 is reported. Rings A and C of atropurpuran were assembled stereoselectively via two intramolecular Michael additions. The advanced tricyclic skeleton 5 shows the correct functionality and stereochemistry for atropurpuran 1, so the skeleton may serve as a key intermediate in its total synthesis.
- Chen, Huan,Li, Xiao-Huan,Gong, Jing,Song, Hao,Liu, Xiao-Yu,Qin, Yong
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Read Online
- Direct Acetoxylation of Arenes
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Acetoxylation of arenes is an important reaction and an unmet need in chemistry. We report a metal-free, direct acetoxylation reaction using sodium nitrate under an anhydrous environment of trifluoroacetic acid, acetic acid, and acetic anhydride. Arenes (31 examples), with oxidation potentials (Eox, in V vs SCE) lower than benzene (2.48 V), were acetoxylated with good yields and regioselectivity. A stepwise, single electron-transfer mechanism is proposed.
- Hong Nguyen, Thi Anh,Hou, Duen-Ren
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supporting information
p. 8127 - 8131
(2021/08/23)
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- carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
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Here we report a new robust nicotinamide dinucleotide phosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time at elevated temperatures since it significantly disfavors hydrolysis of the pyridinium-N?glycoside bond. Overall, more than 27 different oxidoreductases were successfully tested, and a thorough analytical characterization and comparison is given. The cofactor carba-NADP+ opens up the field of redox-biocatalysis under harsh conditions.
- D?ring, Manuel,Sieber, Volker,Simon, Robert C.,Tafertshofer, Georg,Zachos, Ioannis
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supporting information
p. 14701 - 14706
(2021/05/13)
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- Stereoselective synthesis of selenium-containing glycoconjugates via the mitsunobu reaction
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A simple and efficient route for the synthesis of new glycoconjugates has been developed. The approach acts as a model for a mini-library of compounds with a deoxy-selenosugar core joined to a polyphenolic moiety with well-known antioxidant properties. An unexpected stereocontrol detected in the Mitsunobu key reaction led to the most attractive product showing a natural Dconfiguration. Thus, we were able to obtain the target molecules from the commercially available D-ribose via a shorter and convenient sequence of reactions.
- Cermola, Flavio,De Nisco, Mauro,Manfra, Michele,Pedatella, Silvana,Serpico, Luigia
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- Aqueous microdroplets containing only ketones or aldehydes undergo Dakin and Baeyer-Villiger reactions
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The Dakin and Baeyer-Villiger (BV) oxidation reactions require addition of peroxides as oxidants and an acid or a base as a catalyst. Reaction times range from hours to days to obtain target products. Previously, we reported that hydrogen peroxide (H2O2) is spontaneously generated in water microdroplets without any added chemicals or applied electrical potential. Here, we report that the Dakin and BV reactions occur in modest yields within milliseconds in aqueous microdroplets at room-temperature without the addition of external peroxides and catalysts. H2O2 generation is the result of the special environment of the microdroplet surface, which promotes water autoionization. We find that increasing the content of water and decreasing the droplet size improve the product yield of the Dakin and BV reactions, supporting the contention that the amount of H2O2 generated in aqueous microdroplets could induce the two reactions and the reactions occur at or near the air-water interface of the microdroplet surface.
- Gao, Dan,Jin, Feng,Lee, Jae Kyoo,Zare, Richard N.
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p. 10974 - 10978
(2019/12/28)
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- Design, synthesis and biological evaluation of curcumin analogues as novel LSD1 inhibitors
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Histone lysine-specific demethylase 1 (LSD1) was the first discovered histone demethylase. Inactivating LSD1 or downregulating its expression inhibits cancer-cell development, and thus, it is an attractive molecular target for the development of novel cancer therapeutics. In this study, we worked on the structural optimization of natural products and identified 30 novel LSD1 inhibitors. Utilizing a structure-based drug design strategy, we designed and synthesized a series of curcumin analogues that were shown to be potent LSD1 inhibitors in the enzyme assay. Compound WB07 displayed the most potent LSD1 inhibitory activity, with an IC50 value of 0.8 μM. Moreover, WA20 showed an anticlonogenic effect on A549 cells with an IC50 value of 4.4 μM. Molecular docking simulations were also carried out, and the results indicated that the inhibitors bound to the protein active site located around the key residues of Asp555 and Asp556. These findings suggested that compounds WA20 and WB07 are the first curcumin analogue-based LSD1 inhibitors with remarkable A549 suppressive activity, providing a novel scaffold for the development of LSD1 inhibitors.
- Wang, Jiming,Zhang, Xiangyu,Yan, Jiangkun,Li, Wei,Jiang, Qinwen,Wang, Xinran,Zhao, Dongmei,Cheng, Maosheng
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supporting information
(2019/10/22)
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- C70 Fullerene-Catalyzed Metal-Free Photocatalytic ipso-Hydroxylation of Aryl Boronic Acids: Synthesis of Phenols
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A metal-free C70 fullerene-catalyzed method has been developed for the ipso-hydroxylation of aryl and heteroaryl boronic acids to corresponding phenols under photocatalytic conditions. The reaction proceeds under oxygen atmosphere and the mechanistic study revealed that C70 plays a critical role in the generation of reactive oxygen species in the presence of blue light. Reactions in the presence of 18O-labelled water and oxygen confirmed the generation of reactive oxygen species from oxygen molecule. Amine used as a reductant could be recovered in the form of imine. The current method is also applicable to the synthesis of aryl ethers in one-pot two-step process. (Figure presented.).
- Kumar, Inder,Sharma, Ritika,Kumar, Rakesh,Kumar, Rakesh,Sharma, Upendra
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supporting information
p. 2013 - 2019
(2018/04/02)
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- Total Synthesis of Divergolides E and H
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This manuscript describes the first total syntheses of divergolides E and H. The route employs a telescoped hetero-Diels–Alder and oxidative carbon–hydrogen bond cleavage as an entry into the central bridged bicyclic acetal unit. Additional key steps of the highly convergent route include a desymmetrizing epoxidation, a chelation-controlled alkenylzinc addition, an amide formation between a hindered aniline and an acylating agent that is prone to ketene formation, and a challenging macrolactonization.
- Caplan, Scott M.,Floreancig, Paul E.
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p. 15866 - 15870
(2018/11/10)
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- KHF2: A mild and selective desilylating agent for phenol tert-butyldimethylsilyl (TBDMS) ethers
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TBDMS (t-BuMe2Si, tert-butyldimethylsilyl) ethers of a variety of phenols have been deprotected with KHF2 in MeOH, at room temperature. Carboxylic ester and labile phenolic acetate were unaffected under these conditions. In competition reactions between TBDMS ethers of a phenol and two primary benzylic alcohols, the phenolic ether underwent cleavage whereas the alcohol ethers remained intact. From a substrate containing both a phenolic hydroxyl group and a secondary, doubly benzylic hydroxyl group protected as TBDMS ethers, the phenol was rapidly and selectively released. Cleavage of TBDMS, TBDPS, and TIPS ethers of a phenol was also compared. TBDMS and TBDPS ethers underwent cleavage at room temperature within 30 minutes, whereas removal of the TIPS ether required 2.5 hours. Ease of cleavage appears to be TBDMS ≈ TBDPS > TIPS. At 60°C, TBDMS ethers of primary benzylic, allylic, and unactivated alcohols can be efficiently desilylated over a prolonged period (13-17 h). Thus, KHF2 proves to be a mild and effective reagent for the selective desilylation of phenol TBDMS ethers at room temperature.
- Lakshman, Mahesh K.,Tine, Fatou A.,Khandaker, Tashrique A.,Basava, Vikram,Agyemang, Nana B.,Benavidez, Michael S.A.,Ga?i, Marikone,Guerrera, Lisa,Zajc, Barbara
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p. 381 - 385
(2017/02/10)
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- Gem difluorocompounds as depigmenting or lightening agents
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The present invention relates to a compound having the formula (I), as well as a method for preparing such a compound, a cosmetic or pharmaceutic composition containing such a compound, and the use thereof as a depigmenting, lightening, bleaching or whitening agent and for treating pigmentation disorders, notably by topical application on the skin.
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Paragraph 0215; 0216
(2017/12/27)
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- Utilization of the inherent nucleophile for regioselective O-acylation of polyphenols via an intermolecular cooperative transesterification
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A green and efficient method for regioselective O-acylation of polyphenols has been developed. The acylation can be carried out in potassium carbonate/dimethyl sulphoxide system by utilizing the ‘inherent nucleophile’ via an intermolecular cooperative transesterification under mild condition. This method shows particular advantage in regioselective acylation of polyphenols bearing 2′,4′-dihydroxyacetophenone moiety and can be extended to the synthesis of mono or multiple acetates of polyphenols without this moiety in good yields. Compared with other reported approaches, this method is endowed with atom economy and is more environment-friendly for avoiding the use of any metal-based catalysts.
- Liu, Jingchao,Fu, Junjie,Li, Wenlong,Zou, Yu,Huang, Zhangjian,Xu, Jinyi,Peng, Sixun,Zhang, Yihua
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p. 4103 - 4110
(2016/07/06)
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- Stabilized Fe3O4 magnetic nanoparticles into nanopores of modified montmorillonite clay: A highly efficient catalyst for the Baeyer-Villiger oxidation under solvent free conditions
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In situ generation of Fe3O4 magnetic nanoparticles (Fe3O4@AT-mont.) into the nanopores of modified montmorillonite (AT-mont.) clay has been carried out. Modification of the montmorillonite was done by acid (4 M HCl) activation under controlled conditions for generating nanopores, which act as a "host" for the Fe3O4 nanoparticles. The synthesized Fe3O4@AT-mont. was characterized by PXRD, TEM, SEM-EDX, XPS, VSM and surface area analysis. The average particle size of Fe3O4 nanoparticles was found to be around 10 nm and exhibit a face centered cubic (fcc) lattice geometry. Fe3O4@AT-mont. showed efficient catalytic activity for the Baeyer-Villiger oxidation of various cyclic and aromatic ketones in the presence of hydrogen peroxide as an oxidant at room temperature under solvent free conditions and exhibited conversion of up to 98%. The catalyst was magnetically recovered and recycled up to the third run without any significant loss of efficiency.
- Saikia, Pallab Kumar,Sarmah, Podma Pollov,Borah, Bibek Jyoti,Saikia, Lakshi,Saikia, Kokil,Dutta, Dipak Kumar
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p. 2843 - 2850
(2016/06/06)
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- Structural and catalytic characterization of a fungal baeyer-villiger monooxygenase
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Baeyer-Villiger monooxygenases (BVMOs) are biocatalysts that convert ketones to esters. Due to their high regio-, stereo- and enantioselectivity and ability to catalyse these reactions under mild conditions, they have gained interest as alternatives to chemical Baeyer-Villiger catalysts. Despite their widespread occurrence within the fungal kingdom, most of the currently characterized BVMOs are from bacterial origin. Here we report the catalytic and structural characterization of BVMOAFL838 from Aspergillus flavus. BVMOAFL838 converts linear and aryl ketones with high regioselectivity. Steady-state kinetics revealed BVMOAFL838 to show significant substrate inhibition with phenylacetone, which was more pronounced at low pH, enzyme and buffer concentrations. Para substitutions on the phenyl group significantly improved substrate affinity and increased turnover frequencies. Steady-state kinetics revealed BVMOAFL838 to preferentially oxidize aliphatic ketones and aryl ketones when the phenyl group are separated by at least two carbons from the carbonyl group. The X-ray crystal structure, the first of a fungal BVMO, was determined at 1.9 A and revealed the typical overall fold seen in type I bacterial BVMOs. The active site Arg and Asp are conserved, with the Arg found in the ginh position. Similar to phenylacetone monooxygenase (PAMO), a two residue insert relative to cyclohexanone monooxygenase (CHMO) forms a bulge within the active site. Approximately half of the gvariableh loop is folded into a short ?-helix and covers part of the active site entry channel in the non-NADPH bound structure. This study adds to the current efforts to rationalize the substrate scope of BVMOs through comparative catalytic and structural investigation of different BVMOs.
- Ferroni, Felix Martin,Tolmie, Carmien,Smit, Martha Sophia,Opperman, Diederik Johannes
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- Method for synthesizing 4-butoxyphenol
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The invention provides a method for synthesizing 4-butoxyphenol. The method comprises the steps of firstly, protecting one of two hydroxyl groups of hydroquinone with an acetyl group, enabling the hydroquinone to be converted into a mono-hydroxyl protected product in an almost-isometric manner by using an ester exchange reaction, then, subjecting the mono-hydroxyl protected product to a reaction with halogenated butane so as to etherifying the unprotected hydroxyl group, and then, carrying out hydrolysis to remove acetyl protection, thereby obtaining high-yield 4-butoxyphenol. According to the method, the control is simple, the yield is stable, and the purity of the synthesized product reaches 98% or more through simple crystallization in an aqueous solution.
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Paragraph 0016
(2017/07/19)
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- Direct synthesis of anilines and nitrosobenzenes from phenols
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A one-pot synthesis of anilines and nitrosobenzenes from phenols has been developed using an ipso-oxidative aromatic substitution (iSOAr) process. The products are obtained in good yields under mild and metal-free conditions. The leaving group effect on reactions that proceed through mixed quionone monoketals has also been investigated and a predictive model has been established.
- St Amant,Frazier,Newmeyer,Fruehauf,Read De Alaniz
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supporting information
p. 5520 - 5524
(2016/07/06)
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- P4VPy–CuO nanoparticles as a novel and reusable catalyst: application at the protection of alcohols, phenols and amines
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P4VPy–CuO nanoparticles were synthesized using ultrasound irradiations. Relevant properties of the synthesized nanoparticles were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. After identification, the prepared reagent was used for the promotion of different types of protection reactions of alcohols, phenols and amines. Easy workup, short reaction times, excellent yields, relatively low cost and reusability of the catalyst are the striking features of the reported methods.
- Shirini, Farhad,Fallah-Shojaei, Abdollah,Abedini, Masoumeh,Samavi, Laleh
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p. 1699 - 1712
(2016/07/27)
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- Oxidation with air by ascorbate-driven quinone redox cycling
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Transition metal-free oxidation with air at room temperature has been achieved by simply using ascorbate (vitamin C) and catalytic amounts of menadione (vitamin K3). A combination of the mentioned vitamins transforms atmospheric oxygen into hydrogen peroxide, which is able to oxidize arylboronic acids and other chemical moieties. This journal is
- Silveira-Dorta, Gastón,Monzón, Diego M.,Crisóstomo, Fernando P.,Martín, Tomás,Martín, Víctor S.,Carrillo, Romen
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supporting information
p. 7027 - 7030
(2015/04/22)
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- P-Benzoquinone adsorption-separation, sensing and its photoinduced transformation within a robust Cd(II)-MOF in a SC-SC fashion
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p-Benzoquinone (Q) adsorption-separation, sensing and its photoinduced transformation within a robust Cd(ii)-MOF (1) is reported. All the adsorption, sensing and photochemical reactions are directly performed on the single-crystals of 1. This journal is
- Yang, Fan,Liu, Qi-Kui,Wu, Dan,Li, An-Yan,Dong, Yu-Bin
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supporting information
p. 7443 - 7446
(2015/05/04)
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- Design, synthesis and docking studies of novel thienopyrimidine derivatives bearing chromone moiety as mTOR/PI3Kα inhibitors
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Two series of thienopyrimidine derivatives (10a-k, 16a-j) bearing chromone moiety were designed and synthesized. All the compounds were evaluated for inhibitory activity against mTOR kinase at a concentration of 10uM. Four selected compounds were further evaluated for the IC50 values against mTOR kinase, PI3Kα kinase and two cancer cell lines. Some of the target compounds exhibited moderate to excellent mTOR/PI3Kα kinase inhibitory activity and cytotoxicity. The most promising compound 16i showed good inhibitory activity against mTOR/PI3Kα kinase and good antitumor potency for H460 and PC-3 cell lines with IC50 values of 0.16 ± 0.03 μM, 2.35 ± 0.19 μM, 1.20 ± 0.23 μM and 0.85 ± 0.04 μM, which were 8.6, >5, 7.9 and 19.1 times more active than compound I (1.37 ± 0.07 μM, >10 μM, 9.52 ± 0.29 μM, 16.27 ± 0.54 μM), respectively. Structure-activity relationships (SARs) and docking studies indicated that the chromone moiety is necessary for the potent antitumor activity and cytotoxicity of these compounds. Substitution of the chromone moiety at the 6-position has a significant impact to the inhibitory activity, in particular a carboxylic acid group, produced the best potency.
- Zhu, Wufu,Chen, Chen,Sun, Chengyu,Xu, Shan,Wu, Chunjiang,Lei, Fei,Xia, Hui,Tu, Qidong,Zheng, Pengwu
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- Structural characterization and function determination of a nonspecific carboxylate esterase from the amidohydrolase superfamily with a promiscuous ability to hydrolyze methylphosphonate esters
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The uncharacterized protein Rsp3690 from Rhodobacter sphaeroides is a member of the amidohydrolase superfamily of enzymes. In this investigation the gene for Rsp3690 was expressed in Escherichia coli and purified to homogeneity, and the three-dimensional structure was determined to a resolution of 1.8 ? The protein folds as a distorted (β/α)8-barrel, and the subunits associate as a homotetramer. The active site is localized to the C-terminal end of the β-barrel and is highlighted by the formation of a binuclear metal center with two manganese ions that are bridged by Glu-175 and hydroxide. The remaining ligands to the metal center include His-32, His-34, His-207, His-236, and Asp-302. Rsp3690 was shown to catalyze the hydrolysis of a wide variety of carboxylate esters, in addition to organophosphate and organophosphonate esters. The best carboxylate ester substrates identified for Rsp3690 included 2-naphthyl acetate (kcat/Km = 1.0 × 105 M-1 s-1), 2-naphthyl propionate (k cat/Km = 1.5 × 105 M-1 s -1), 1-naphthyl acetate (kcat/Km = 7.5 × 103 M-1 s-1), 4-methylumbelliferyl acetate (kcat/Km = 2.7 × 103 M-1 s-1), 4-nitrophenyl acetate (kcat/Km = 2.3 × 105 M-1 s-1), and 4-nitrophenyl butyrate (kcat/Km = 8.8 × 105 M -1 s-1). The best organophosphonate ester substrates included ethyl 4-nitrophenyl methylphosphonate (kcat/Km = 3.8 × 105 M-1 s-1) and isobutyl 4-nitrophenyl methylphosphonate (kcat/Km = 1.1 × 104 M-1 s-1). The (SP)-enantiomer of isobutyl 4-nitrophenyl methylphosphonate was hydrolyzed 10 times faster than the less toxic (RP)-enantiomer. The high inherent catalytic activity of Rsp3690 for the hydrolysis of the toxic enantiomer of methylphosphonate esters make this enzyme an attractive target for directed evolution investigations.
- Xiang, Dao Feng,Kumaran, Desigan,Swaminathan, Subramanyam,Raushel, Frank M.
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p. 3476 - 3485
(2014/06/23)
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- Functional divergence between closely related Baeyer-Villiger monooxygenases from Aspergillus flavus
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Baeyer-Villiger monooxygenases (BVMOs) catalyse the chemo-, regio- and enantioselective oxidation of ketones to esters and lactones. To date, most of the cloned BVMOs available are derived from bacteria, although Baeyer-Villiger oxidations using fungi have frequently been demonstrated. Here we report the cloning and characterization of four BVMOs from the fungus Aspergillus flavus NRRL3357. Phylogenetic analysis shows these four BVMOs to cluster in a distinct group apart from other well-characterized BVMOs including cyclohexanone, phenylacetone and 4-hydroxyacetophenone monooxygenase. Building on the Grogan classification/clustering of BVMOs, we have designated this new group of BVMOs, Group VI. Group VI BVMOs show an early divergence from the cyclopentanone monooxygenase (CPMO) type BVMOs (Group I). Substrate profiling using cyclic, bicyclic, aliphatic and aryl ketones show a clear divergence in function and specificity not only between this new group of BVMOs and the CPMO-type BVMOs, but also between the four A. flavus BVMO paralogues despite their high sequence similarity. This study not only contributes to the growing number of available BVMOs, but also addresses the current classification of Type I BVMOs, and the usefulness of phylogenetic clustering and prediction of function and selectivity when genome-mining is used to search for new biocatalysts.
- Ferroni,Smit,Opperman
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- Silica-supported boric acid catalyzed synthesis of dihydropyrimidin-2-ones, bis(indolyl)methanes, esters and amides
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Silica-supported boric acid (H3BO3-SiO2) has been established as a green, efficient and recyclable catalyst for the synthesis of dihydropyrimidin-2-ones, bis(indolyl)methanes, and acetylation of alcohols, phenols, amines and thiols under solvent free conditions. The main features of the present method include clean reaction, mild conditions, low loading of environment friendly catalyst and easy workup procedure. The catalyst can be recycled at least five times without any significant loss in activity.
- Kumar, Vishal,Singh, Chitra,Sharma, Upendra,Verma, Praveen K.,Singh, Bikram,Kumar, Neeraj
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- The rearrangement of tert -butylperoxides for the construction of polysubstituted furans
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The Bronsted acid catalyzed rearrangement of tert-butyl peroxides provides a new strategy to construct 2,3-disubstituted furans via 1,2-aryl migration. In addition, tert-butyl peroxides could also be transformed into 2,3,5-trisubstituted or 2,5-disubstituted furans through a sequence of base-catalyzed Kornblum-DelaMare rearrangements and acid-promoted Paal-Knorr reactions.
- Zheng, Xiaojian,Lu, Shenglin,Li, Zhiping
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supporting information
p. 5432 - 5435
(2013/11/19)
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- POLYMERIC BIOMATERIALS DERIVED FROM PHENOLIC MONOMERS AND THEIR MEDICAL USES
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The present invention provides new classes of phenol compounds, including those derived from tyrosol and analogues, useful as monomers for preparation of biocompatible polymers, and biocompatible polymers prepared from these monomeric phenol compounds, including novel biodegradable and/or bioresorbable polymers. These biocompatible polymers or polymer compositions with enhanced bioresorbabilty and processibility are useful in a variety of medical applications, such as in medical devices and controlled-release therapeutic formulations. The invention also provides methods for preparing these monomeric phenol compounds and biocompatible polymers.
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Paragraph 0215
(2013/08/15)
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- Design and syntheses of novel N′-((4-oxo-4H-chromen-3-yl)methylene) benzohydrazide as inhibitors of cyanobacterial fructose-1,6-/sedoheptulose-1,7- bisphosphatase
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Cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphoshatase (Cy-FBP/SBPase) is an important target enzyme for finding inhibitors to solve harmful algal bloom (HAB). In this study, as potential inhibitors of Cy-FBP/SBPase, a series of novel chromone-connecting benzohydrazone compounds (Novel N′-((4-oxo-4H-chromen-3-yl)methylene)benzohydrazide) were designed and synthesized. Their inhibitory activities against Cy-FBP/SBPase were further examined in vitro. Some of these compounds, such as f6-f8, f11, f12 and f16, exhibit higher inhibitory activities (IC50 = 11.2-16.1 μM), especially, the compound f7 was identified as the most potent inhibitor with IC50 value of 11.2 μM. The probable binding-mode of compound f7 was further analyzed carefully by molecular docking methods. These results indicate that compound f7 could be used as a lead compound for further optimization and might have potential to be developed as a new algicide.
- Tu, Qi-Dong,Li, Ding,Sun, Yao,Han, Xin-Ya,Yi, Fan,Sha, Yibamu,Ren, Yan-Liang,Ding, Ming-Wu,Feng, Ling-Ling,Wan, Jian
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p. 2826 - 2831
(2013/06/27)
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- HF-Pyridine: A versatile promoter for monoacylation/sulfonylation of phenolic diols and for direct conversion of t-butyldimethylsilyl ethers to the corresponding acetates
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Monoacylation and trifluoromethanesulfonylation of phenolic diols were achieved by the aid of HF-pyridine, whereas diacylation occurred with pyridine alone. Furthermore, HF-pyridine was found to promote the direct conversion of t-butyldimethylsilyl ethers to the corresponding acetates.
- Michigami, Kyosuke,Yoshimoto, Kazuya,Hayashi, Masahiko
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scheme or table
p. 138 - 139
(2012/03/09)
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- Characterization of novel Cs and K substituted phosphotungstic acid modified MCM-41 catalyst and its catalytic activity towards acetylation of aromatic alcohols
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TheMCM-41 supported Cs2.5H0.5PW12O 40 and K2.5H0.5PW12O40 salts were synthesized by incipient wetness impregnation method. The solids were characterized by N2 adsorption-desorption isotherms, FTIR, XRD, and temperature programmed desorption, etc. This catalyst has been found to exhibit excellent activity for acetylation of phenolic compounds. The catalyst is stable and reusable giving 96% conversion with 100% selectivity towards acetate products. Indian Academy of Sciences.
- Rana, Surjyakanta,Mallick, Sujata,Rath, Dharitri,Parida
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p. 1117 - 1125
(2013/03/13)
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- Sonochemical synthesis of silica and silica sulfuric acid nanoparticles from rice husk ash: A new and recyclable catalyst for the acetylation of alcohols and phenols under heterogeneous conditions
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Silica nanoparticles were synthesized from rice husk ash at room temperature by sonochemical method. The feeding rate of percipiteting agent and time of sonication were investigated. The nanostructure of the synthesized powder was realized by the FE-SEM photomicrograph, FT-IR spectroscopy, XRD and XRF analyses. These analytical observations have revealed that the nano-sized amorphous silica particles are formed and they are spheroidal in shape. The average particle size of the silica powders is found to be around 50 nm. The as-synthesized silica nanoparticles were subsequently modified with chlorosulfonic acid and prepared silica sulfuric acid nanoparticles, which were employed as an efficient catalyst for the acylation of alcohols and phenols with acetic anhydride in excellent yields under solvent-free conditions at room temperature. This reported method is simple, mild, and environmentally viable and catalyst can be simply recovered and reused over 9 times without any significant loss of its catalytic activity.
- Salavati-Niasari, Masoud,Javidi, Jaber
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p. 705 - 712
(2013/02/22)
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- First total chemical synthesis of natural acyl derivatives of some phenolglycosides of the family Salicaceae
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The total synthesis of certain natural phenolglycosides of the family Salicaceae, namely: salireposide, populosides A, B, and C and not occurring in plants desoxysalireposide (2-(β-d-glucopyranosyloxy)-benzylbenzoate) and per-acetate of iso-salireposide (2-(β-d-glucopyranosyloxy)-5-benzoyloxy benzyl alcohol), starting from readily available phenols and glucose was accomplished. A simple method for the synthesis of phenolglycosides derivatives of 2-acyloxy salicyl and gentisyl alcohol was developed. The key step of these natural products' synthesis is a selective removal of acetyl groups in the presence of other acyl groups.
- Belyanin, Maxim L.,Stepanova, Elena V.,Ogorodnikov, Vladimir D.
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- Selective oxidations of organoboron compounds catalyzed by Baeyer-Villiger monooxygenases
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The applicability of Baeyer-Villiger monooxygenases (BVMOs) in organoboron chemistry has been explored through testing chemo- and enantioselective oxidations of a variety of boron-containing aromatic and vinylic compounds. Several BVMOs, namely: phenylacetone monooxygenase (PAMO), M446G PAMO mutant, 4-hydroxyacetophenone monooxygenase (HAPMO) and cyclohexanone monooxygenase (CHMO) were used in this study. The degree of chemoselectivity depends on the type of BVMO employed, in which the biocatalysts prefer boron-carbon oxidation over Baeyer-Villiger oxidation or epoxidation. Interestingly, it was discovered that PAMO can be used to perform kinetic resolution of boron-containing compounds with good enantioselectivities. These findings extend the known biocatalytic repertoire of BVMOs by showing a new family of compounds that can be oxidized by these enzymes. Copyright
- Brondani, Patricia B.,De Gonzalo, Gonzalo,Fraaije, Marco W.,Andrade, Leandro H.
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supporting information; experimental part
p. 2169 - 2173
(2011/10/31)
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- Oxidation of organoselenium compounds. A study of chemoselectivity of phenylacetone monooxygenase
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Organoselenium acetophenones oxidation using enzymatic reactions has been developed and chemoselectivity of phenylacetone monooxygenase (PAMO) with selenium-containing ketones has been explored. We discovered that this biocatalyst prefers selenium oxidation, which leads to selenoxide in excellent conversion, over Baeyer-Villiger oxidation.
- Andrade, Leandro H.,Pedrozo, Eliane C.,Leite, Henrique G.,Brondani, Patricia B.
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body text
p. 63 - 66
(2012/02/13)
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- Synthesis and anti-melanogenic activity of hydroxyphenyl benzyl ether analogues
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In order to develop potent skin whitening agents, we have synthesized 17 hydroxyphenyl benzyl ether compounds and tested their melanin synthesis inhibitory activity, DPPH free radical scavenging activity and tyrosinase inhibitory activity. Compounds 32, 35 and 36 possessing 4-hydroxyphenyl benzyl ether structure showed excellent inhibitory capacity with almost 50-fold than arbutin used as a reference in the inhibition test of α-MSH stimulated melanin synthesis in B-16 cells. 4-Hydroxyphenyl benzyl ether compounds also showed good antioxidant activity in the DPPH free radical scavenging test. The tyrosinase function was effectively inhibited by 3,5-dihydroxyphenyl benzyl ether analogues, especially compounds 18, 22, and 24.
- Sapkota, Kiran,Roh, Eunmiri,Lee, Eunyoung,Ha, Eun-Mi,Yang, Jae-Ho,Lee, Eung-Seok,Kwon, Youngjoo,Kim, Youngsoo,Na, Younghwa
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experimental part
p. 2168 - 2175
(2011/05/11)
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- Stereoselective umpolung tandem addition of heteroatoms to phenol
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Upon coordination to {TpW(PMe3)(NO)}, phenol tautomerizes to a cyclohexadienone (a 2H-phenol). The uncoordinated, nonaromatic double bond of this ligand undergoes stepwise addition of electrophiles followed by nucleophiles to produce 4,5-disubstituted cyclohexenone complexes. The metal stabilizes the intermediate cationic ligand and sterically blocks one face of the ligand, resulting in a high degree of stereo- and regiocontrol. These substituted cyclohexenones are readily liberated from the metal by oxidative decomplexation. Copyright
- Todd, Michael A.,Sabat, Michal,Myers, William H.,Smith, Timothy M.,Harman, W. Dean
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p. 6906 - 6907
(2008/12/21)
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- Method for producing hydroxyphenyl acrylate monomers and polymers
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New syntheses of phenolic acrylate monomers are provided as well as polymers comprising such phenolic acrylate monomers. Preferred polymers of the invention are useful as a resin component of chemically-amplified positive-acting resists.
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Page/Page column 5-6
(2008/12/08)
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- Chemistry of 4-alkylaryloxenium ion "precursors": Sound and fury signifying something?
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(Chemical Equation Presented) Quinol esters 2b, 2c, and 3b and sulfonamide 4c were investigated as possible precursors to 4-alkylaryloxenium ions, reactive intermediates that have not been previously detected. These compounds exhibit a variety of interesting reactions, but with one possible exception, they do not generate oxenium ions. The 4-isopropyl ester 2b predominantly undergoes ordinary acid- and base-catalyzed ester hydrolysis. The 4-tert-butyl ester 2c decomposes under both acidic and neutral conditions to generate tert-butanol and 1-acetyl-1,4-hydroquinone, 8, apparently by an SN1 mechanism. This is also a minor decomposition pathway for 2b, but the mechanism in that case is not likely to be SN1. Decomposition of 2c in the presence of N 3- leads to formation of the explosive 2,3,5,6-tetraazido-1,4-benzoquinone, 14, produced by N3 -induced hydrolysis of 8, followed by a series of oxidations and nucleophilic additions by N3 . No products suggestive of N3--trapping of an oxenium ion were detected. The 4-isopropyl dichloroacetic acid ester 3b reacts with N3- to generate the two adducts 2-azido-4-isopropylphenol, 5b, and 3-azido-4-isopropylphenol, 11b. Although 5b is the expected product of N3- trapping of the oxenium ion, kinetic analysis shows that it is produced by a kinetically bimolecular reaction of N3- with 3b. No oxenium ion is involved. The sulfonamide 4c predominantly undergoes a rearrangement reaction under acidic and neutral conditions, but a minor component of the reaction yields 4-tert-butylcresol, 17, and 2-azido-4-tert-butylphenol, 5c, in the presence of N3-. These products may indicate that 4c generates the oxenium ion 1c, but they are generated in very low yields (ca. 10%) so it is not possible to definitively conclude that 1c has been produced. If 1c has been generated, the N3--trapping data indicate that it is a very short-lived and reactive species in H2O. Comparisons with similarly reactive nitrenium ions indicate that the lifetime of 1c is ca. 20-200 ps if it is generated, so it must react by a preassociation process. Density functional theory calculations at the B3LYP/6-31G*//HF/6-31G* level coupled with kinetic correlations also indicate that the aqueous solution lifetimes of 1a-c are in the picosecond range.
- Novak, Michael,Brinster, Aaron M.,Dickhoff, Jill N.,Jones, Matthew P.,Leopold, Samuel H.,Vollman, Andrew T.,Wang, Yue-Ting,Glover, Stephen A.
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p. 9954 - 9962
(2008/09/18)
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- Ring-closing metathesis dimerizations of enynes and deprotections of propargyl ethers mediated by carbene ruthenium complexes
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The ring-forming dimerizations of enynes were catalyzed by the first-generation carbene ruthenium complex, and the effects of the catalysts and ethylene gas were studied. The deprotection of propargyl ethers by the carbene ruthenium complexes is the first to be reported. Wiley-VCH Verlag GmbH & Co. KGaA1 69451 Weinheim, Germany, 2005.
- Hahn, Dong-Woo,Byun, Dong-Min,Tae, Jinsung
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- Enzymatic Baeyer-Villiger oxidation of benzaldehydes
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The selectivity of the chemical Baeyer-Villiger oxidation of benzaldehydes depends on steric and electronic factors, the type of oxidizing agent and the reaction conditions. Here we report on the enzymatic Baeyer-Villiger oxidation of fluorobenzaldehydes
- Moonen, Marielle J. H.,Westphal, Adrie H.,Rietjens, Ivonne M. C. M.,Van Berkel, Willem J. H.
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p. 1027 - 1034
(2007/10/03)
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- Antimicrobial activity of p-hydroxyphenyl acrylate derivatives
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To estimate the antimicrobial effect of p-hydroxyphenyl acrylate (H5) derivatives on the basis of their molecular structure, the hydroxy and acryl groups of p-hydroxyphenyl acrylate were modified. The antimicrobial activity of the resulting compounds was assessed against a Gram-positive bacterium (Staphylococcus aureus), a Gram-negative bacterium (Pseudomonas aeruginosa), and fungi (Aspergillus fumigatus and Penicillium pinphilum) by the halo zone and the shake flask test. The antimicrobial activity of H5 was ascribed mainly to the acryl group. Compounds with acryl or acryloxy groups bound to the phenyl moiety were found to exhibit particularly high antimicrobial activities. The activities of phenyl acrylate and phenyl vinyl ketone were excellent as compared to aliphatic acrylates such as cyclohexyl acrylate and hexyl acrylate, indicating that the stereoelectronic effect of the phenyl group was important to the antimicrobial activity.
- Jung, Hee Kim,Park, Eun-Soo,Jae, Hun Shim,Kim, Mal-Nam,Moon, Woong-Sik,Chung, Kyoo-Hyun,Yoon, Jin-San
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p. 7480 - 7483
(2007/10/03)
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- COMPOUNDS WITH MIXED PDE-INHIBITORY AND β-ADRENERGIC ANTAGONIST OR PARTIAL AGONIST ACTIVITY FOR TREATMENT OF HEART FAILURE
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This invention provides compounds that possess inhibitory activity against β--adrenergic receptors and phosphodiesterase PDE, including phosphodiesterase 3 (PDE3 ). This invention further provides pharmaceutical compositions comprising such -compounds; methods of using such compounds for treating cardiovascular disease, stroke, epilepsy, ophthalmic disorder or migraine; and methods of preparing pharmaceutical compositions and compounds that possess inhibitory activity against ?-adrenergic receptors and PDE.
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- Simple, efficient, and selective deprotection of phenolic methoxymethyl ethers using silica-supported sodium hydrogen sulfate as a heterogeneous catalyst
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A simple and efficient method has been developed for chemoselective deprotection of phenolic methoxymethyl (MOM) ethers using silica-supported sodium hydrogen sulfate as a heterogeneous catalyst. The conversions occur at room temperature, and the yields of the deprotected phenols are excellent. The method is suitable for deprotection of phenolic MOM ethers of multifunctional bioactive natural products.
- Ramesh,Ravindranath,Das, Biswanath
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p. 7101 - 7103
(2007/10/03)
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- Optically active compound and photosensitive resin composition
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A photoactive compound is used in combination with a photosensitizer, represented by the following formula (1): A?[(J)m?(X-Pro)]n ??(1) wherein A represents a hydrophobic unit comprising at least one kind of hydrophobic groups selected from a hydrocarbon group and a heterocyclic group, J represents a connecting group, X-Pro represents a hydrophilic group protected by a protective group Pro which is removable by light exposure, m represents 0 or 1, and n represents an integer of not less than 1. The protective group Pro may be removable by light exposure in association with the photosensitizer (especially, a photo acid generator), or may be a hydrophobic protective group. The hydrophilic group may be a hydroxyl group or a carboxyl group. The photoactive compound has high sensitivity to a light source of short wavelength beams, for resist application, therefore, the photoactive compound is advantageously used for forming a pattern with high resolution.
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- A novel method for the regeneration of alcohols from toluene sulphonates using CeCl3. 7H2O -NaI system
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Treatment of aryl and alkyl tosylates with Cerium(III) chloride hepta hydrate and sodium iodide in acetonitrile provides a simple, convenient and chemoselective procedure for the detosylatlon.
- Sudhakar Reddy,Hari Mohan,Iyengar
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p. 3829 - 3832
(2007/10/03)
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- Lipase PS-C catalysed hydrolysis of aryl diesters: A new route to the synthesis of achiral half esters
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Pseudomonas cepacia lipase supported on ceramic particles (PS-C) offers a simple alternative route for the synthesis of achiral half esters, with very high yields, easy work up and remarkable substrate selectivity, as it cleaves only phenolic esters having a phenyl group (i.e. C6H5-O-CO-C6H5).
- Nair, Ranjeet V.,Shukla, Manojkumar R.,Patil, Prashant N.,Salunkhe, Manikrao M.
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p. 1671 - 1677
(2007/10/03)
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- On the mechanism of alkaline hydrogen peroxide oxidation of the lignin model p-hydroxyacetophenone
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The oxidation of p-hydroxyacetophenone by a small excess of alkaline hydrogen peroxide has been found to be an autocatalysed process in which hydroquinone monoacetate and the peracetate ion are generated and consumed at similar rates. The reaction proceeds at a maximum rate when the base concentration is about 0.3 M. A chain-type mechanism that involves peracetate as the oxidizing agent is proposed for the reaction that explains the observed dependence of rate on base concentration. At high pH o-hydroxyacetophenone reacts by the same mechanism, whereas m-hydroxyacetophenone does not react with hydrogen peroxide under these conditions.
- Hocking,Crow
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p. 1137 - 1142
(2007/10/02)
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- The Design and Properties of a Series of Calcium Indicators which Shift from Rhodamine-like to Fluorescein-like Fluorescence on Binding Calcium
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The prototype for a new series of ratio-mode fluorescence indicators of cytosolic free Ca2+ concentration (2+>i) has been developed.The fluorophore, termed FluoRhod, is a hybrid containing elements of the closely related fluorescein and rhodamine structures.The novel feature of the prototype indicator, FluoRhod-2, which incorporates a tetracarboxylate chelating element similar to that of 1,2-bisethane-N,N,N',N'-tetraacetic acid (BAPTA), is that it shifts from rhodamine- to fluorescein-like fluorescence on binding Ca2+.The synthesis and properties of a series of tetracarboxylate derivatives of the FluoRhod fluorophore are described which led to the FluoRhod-2 structure with an apparent dissociation constant for Ca2+ and pKa adjusted to meet the requirements for a 2+>i indicator in the ratio mode.The excitation and emission maxima of FluoRhod-2 are 537 nm and 566 nm in the absence of Ca2+ and 480 nm and 537 nm in the presence of Ca2+.The indicator can be used in either the dual excitation or dual emission mode or the ratio of these two ratios can be used by making dual excitation and dual emission measurements.The brightness of FluoRhod-2 is comparable to that of fura-2 with the advantage of excitation in the visible range.FluoRhod-2 is insensitive to pH from 6.5 to 7.5 when used in the ratio mode, irrespective of the extent to which the indicator is complexed to Ca2+.
- Smith, Gerry A.,Metcalfe, James C.,Clarke, Sonia D.
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p. 1195 - 1204
(2007/10/02)
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- Acid-catalyzed amino-migration of O-phenylhydroxylamines
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The mechanism of amino-migration of O-phenylhydroxylamine (1a) was studied. It was found that 1 rearranges to give 2-aminophenol (50%) and 4-aminophenol (7%) in trifluoroacetic acid (TFA). The predominance of the ortho rearrangement of 1 clearly distinguishes this process from the Bamberger rearrangement. From cross-coupling experiments employing stable isotopes, it was clarified that the ortho rearrangement proceeds intramolecularly and the para rearrangement involves both intra- and intermolecular processes. Good first-order kinetics were obtained for the rearrangement. The Hammett plot (σ+) with a large negative slope (ρ = -7.8) indicates that initial heterolytic N-O bond cleavage of 1 occurs and generates a positive charge on the oxygen atom with considerable delocalization into the aromatic ring. An ion-molecule pair involving a phenoxenium ion and an ammonia molecule as an intermediate rationalizes all of the results. In this pair, intramolecular combination to the ortho position proceeds preferentially over that to the para position. Formation of catechol and hydroquinone can be explained in terms of nucleophilic attack of TFA on the phenoxenium ion in a solvent-separated pair.
- Haga, Naoki,Endo, Yasuyuki,Kataoka, Ken-Ichiro,Yamaguchi, Kentaro,Shudo, Koichi
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p. 9795 - 9806
(2007/10/02)
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- HYDROXYLATION DIRECTE D'ESTERS DE PHENYLE ET D'ANILIDES PAR LE PEROXYDE D'HYDROGENE EN MILIEU SUPERACIDE
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In SbF5-HF, hydrogen peroxide reacts on the aromatic ring of esters 1a-5a and anilides 11a-15a to give monohydroxylated derivatives in good yields.With compounds 2a, 4a and 5a, meta or para isomers are by far the major products, whereas with formate 1a and benzoate 3a, the proportion of the ortho isomer is more important.With anilides, the reaction is less selective, the three isomers being obtained in comparable amounts.Thus, the relative proportions of ortho, meta and para-hydroxylated derivatives obtained using 70 percent H2O2 with acetate 2a and acetanilide 12a are 6/51/43 and 36.5/30/33.5, respectively.The important proportion of meta hydroxylation is the result of the reaction of protonated hydrogen peroxide H3O2+ on the protonated substrate.
- Berrier, Christian,Jacquesy, Jean-Claude,Jouannetaud, Marie-Paule,Morellet, Guy
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p. 158 - 164
(2007/10/02)
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- THE EFFECT OF CARBONYL CONTAINING SUBSTITUENTS IN THE TERMINAL CHAINS ON MESOMORPHIC PROPERTIES IN AROMATIC ESTERS AND THIOESTERS, 2. ACYLOXY GROUPS ON THE PHENOLIC END
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The effect of replacing an alkoxy (Y=OR') with acyloxy (Y=OCOR') group on the phenolic end of the esters: on their mesomorphic properties has been studied.These esters were prepared by esterification of 4-acyloxyphenols with the appropriate acid chloride.The phenols were synthesized by acylation of 4-benzyloxyphenol with either an aliphatic acid or acid chloride followed by catalytic hydrogenolysis of the benzyl group.A comparison of the melting and clearing temperatures of these acyloxy esters with the corresponding known alkoxy ones showed small increases in both these temperatures for the acyloxy esters.The same types of mesophases (N, SA, SC, SB) were observed in both series, but the SB was more favored when Y=OCOR'.The SC phase was found to occur in the acyloxy series at chain lengths beyond which it disappeared in the alkoxy series.Comparisons were also made with the mesomorphic properties previously reported for the correponding alkyl and α-keto esters.Some correlation was observed between increasing dipole moments of these substituents and increasing transition temperatures but not in the types of mesophases observed.Fewer mesophases were found when the alkyl chain was attached to the benzene ring through a carbon atom than through an oxygen atom.
- Neubert, Mary E.,Wildman, Patricia J.,Zawaski, Michael J.,Hanlon, Carol A.,Benyo, Theresa L.,Vries, Adriaan De
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p. 111 - 158
(2007/10/02)
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