- Chiral resolution of racemic p-methylsulfonylphenyl serine ethyl ester with lipases: The mechanism of side reaction and its suppression
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The d-threo form of p-methylsulfonylphenyl serine ethyl ester (MPSE) is a key intermediate for the synthesis of florfenicol. In this study, chiral resolution of dl-threo-p-MPSE with lipases was investigated. Among a series of lipases, Novzyme 435 was the best to resolve dl-threo-p-MPSE with the conversion rate of 36.83% and ee value of 35.13%. To improve the conversion rate and ee value, a number of byproducts were identified and characterized using reverse-phase HPLC, normal-phase HPLC, 1H NMR, and LC-MS when threo-p-MPSE was hydrolyzed by lipases in organic medium. Mechanisms of generating main byproducts are proposed, and a suppressing method is provided. The results showed that byproduct p-methylsulfonyl benzaldehyde serves as the key intermediate during the whole side reaction process. It was also observed that threo-p-MPSE with a proper hydrolytic velocity served as a driving force to generate p-methylsulfonyl benzaldehyde and accelerated the side reactions. Finally, a feasible approach to suppress side reactions in enzymatic catalysis is offered. The conversion rate and ee value were greatly improved by 69.29 and 46.26%, respectively, using Zn2+ compared to those without Zn 2+.
- Guo, Rui,Fan, Yong-Xian,Chen, Xiao-Long,Shen, Yin-Chu
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Read Online
- Selective synthesis of sulfoxides and sulfonesviacontrollable oxidation of sulfides withN-fluorobenzenesulfonimide
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A practical and mild method for the switchable synthesis of sulfoxides or sulfonesviaselective oxidation of sulfides using cheapN-fluorobenzenesulfonimide (NFSI) as the oxidant has been developed. These highly chemoselective transformations were simply achieved by varying the NFSI loading with H2O as the green solvent and oxygen source without any additives. The good functional group tolerance makes the strategy valuable.
- Cao, Zhong-Yan,Li, Xiaolong,Lu, Hao,Wang, Panpan,Wang, Shengqiang,Xu, Xiaobo,Yan, Leyu,Yang, A-Xiu
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supporting information
p. 8691 - 8695
(2021/10/22)
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- COMPOSITES, METHODS AND USES THEREOF
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The present invention relates, in general terms, to methods of catalysing a reaction, including the steps of contacting a chemical entity comprising a sulphide moiety with a composite and an oxidant. The composite acts as a heterogeneous catalyst to oxidise the sulphide moiety. The present invention also relates to composites, methods of synthesising the composites and its use as a catalyst thereof.
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Page/Page column 26
(2021/06/04)
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- Cobalt Single-Atom-Intercalated Molybdenum Disulfide for Sulfide Oxidation with Exceptional Chemoselectivity
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The identification of chemoselective oxidation process en route to fine chemicals and specialty chemicals is a long-standing pursuit in chemical synthesis. A vertically structured, cobalt single atom-intercalated molybdenum disulfide catalyst (Co1-in-MoS2) is developed for the chemoselective transformation of sulfides to sulfone derivatives. The single-atom encapsulation alters the electron structure of catalyst owing to confinement effect and strong metal–substrate interaction, thus enhancing adsorption of sulfides and chemoselective oxidation at the edge sites of MoS2 to achieve excellent yields of up to 99% for 34 examples. The synthetic scopes can be extended to sulfide-bearing alkenes, alkynes, aldehydes, ketones, boronic esters, and amines derivatives as a toolbox for the synthesis of high-value, multifunctional sulfones and late-stage functionalization of pharmaceuticals, e.g., Tamiflu. The synthetic utility of cobalt single atom-intercalated MoS2, together with its reusability, scalability, and simplified purification process, renders it promising for industrial productions.
- Chen, Zhongxin,Liu, Cuibo,Liu, Jia,Li, Jing,Xi, Shibo,Chi, Xiao,Xu, Haisen,Park, In-Hyeok,Peng, Xinwen,Li, Xing,Yu, Wei,Liu, Xiaowang,Zhong, Linxin,Leng, Kai,Huang, Wei,Koh, Ming Joo,Loh, Kian Ping
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- Regio- A nd chemoselective deprotection of primary acetates by zirconium hydrides
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A combination of DIBAL-H and Cp2ZrCl2 is shown to promote the regioselective cleavage of primary acetates on a broad scope of substrates, ranging from carbohydrates to terpene derivatives, with a high tolerance toward protecting groups and numerous functionalities found in natural products and bioactive compounds. Apart from providing highly valuable building blocks in only two steps from biosourced raw materials, this selective de-O-acetylation should also be strongly helpful to solve selectivity issues in organic synthesis.
- Gavel, Marine,Courant, Thibaut,Joosten, Antoine Yvan Philippe,Lecourt, Thomas
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supporting information
p. 1948 - 1952
(2019/04/10)
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- HETEROCYCLIC CARBOXYLIC ACID AMIDE LIGAND AND APPLICATIONS THEREOF IN COPPER CATALYZED COUPLING REACTION OF ARYL HALOGENO SUBSTITUTE
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Provided are a heterocyclic carboxylic acid amide ligand and applications thereof in a copper catalyzed coupling reaction. Specifically, provided are uses of a compound represented by formula (I), definitions of radical groups being described in the specifications. The compound represented by formula (I) can be used as the ligand in the copper catalyzed coupling reaction of the aryl halogeno substitute, and is used or catalyzing the coupling reaction for forming the aryl halogeno substitute having C—N, C—O, C—S and other bonds.
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Paragraph 0293-0294
(2019/05/15)
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- Derivatives of 1H-imidazole-4,5-dicarboxamide and Use Thereof in Preparation of Anticoccidial Drugs
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Disclosed are derivatives of 1H-imidazole-4,5-dicarboxamide and use thereof in preparation of anticoccidial drugs. The derivatives have structural formulae as shown in formulae (I) to (VI). The derivatives of 1H-imidazole-4,5-dicarboxamide as disclosed in the present invention have significant anticoccidial effect, especially against coccidia that show a resistance to other anticoccidial drugs, and thus they can be used in preparation of anticoccidial drug.
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Paragraph 0130-0133
(2019/01/10)
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- A Class of Amide Ligands Enable Cu-Catalyzed Coupling of (Hetero)aryl Halides with Sulfinic Acid Salts under Mild Conditions
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The amide derived from 4-hydroxy-l-proline and 2,6-dimethylaniline is a powerful ligand for Cu-catalyzed coupling of (hetero)aryl halides with sulfinic acid salts, allowing the formation of a wide range of (hetero)aryl sulfones from the corresponding (hetero)aryl halides at considerably low catalytic loadings. The coupling of (hetero)aryl iodides and sodium methanesulfinate proceeds at room temperature with only 0.5 mol % CuI and ligand, representing the first example for Cu-catalyzed arylation at both low catalytic loading and room temperature.
- Zhao, Jinlong,Niu, Songtao,Jiang, Xi,Jiang, Yongwen,Zhang, Xiaojing,Sun, Tiemin,Ma, Dawei
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p. 6589 - 6599
(2018/05/31)
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- INDOLE AND AZAINDOLE HALOALLYLAMINE DERIVATIVE INHIBITORS OF LYSYL OXIDASES AND USES THEREOF
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The present invention relates to novel compounds which are capable of inhibiting certain amine oxidase enzymes. These compounds are useful for treatment of a variety of indications, e.g., fibrosis, cancer and/or angiogenesis in human subjects as well as i
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Paragraph 0222
(2017/09/05)
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- A New Class of Amide Ligands Enable Cu-Catalyzed Coupling of Sodium Methanesulfinate with (Hetero)aryl Chlorides
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((2S,4R)-4-Hydroxy-N-(2-methylnaphthalen-1-yl)pyrrolidine-2-carboxamide (HMNPC), an amide derived from 4-hydroxy-L-proline and 2-methyl naphthalen-1-amine, is a powerful ligand for Cu-catalyzed coupling of (hetero)aryl halides with sulfinic acid salts, allowing for first time the metal-catalyzed coupling of (hetero)aryl chlorides and NaSO2Me. A considerable number of (hetero)aryl chlorides worked well, providing the pharmaceutically important (hetero)aryl methylsulfones in good to excellent yields.
- Ma, Dawei,Niu, Songtao,Zhao, Jinlong,Jiang, Xi,Jiang, Yongwen,Zhang, Xiaojing,Sun, Tiemin
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supporting information
p. 1661 - 1664
(2017/10/30)
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- Combined production method for substituted benzaldehyde, substituted benzyl alcohol and substituted benzoic acid
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The invention discloses a combined production method for substituted benzaldehyde, substituted benzyl alcohol and substituted benzoic acid. The method comprises the following steps: (1) oxidation: a step of continuously introducing substituted toluene, a catalyst and oxygen-contained gas into an oxidation reactor and carrying out reaction so as to obtain oxidation reaction liquid; (2) hydrolyzation: a step of allowing the oxidation reaction liquid to continuously enter a hydrolysis reactor, and continuously adding water into the hydrolysis reactor and carrying out reaction so as to obtain a hydrolysis reaction mixture; (3) liquid-liquid layering: a step of layering the hydrolysis reaction mixture so as to obtain an oil phase and an aqueous phase; and (4) separation of products: a step of subjecting the oil phase to distillation so as to respectively obtain incompletely-reacted substituted toluene, substituted benzyl alcohol and substituted benzaldehyde, and subjecting the aqueous phase to cooling, crystallizing and filtering so as to obtain filtrate and substituted benzoic acid. The combined production method provided by the invention has the advantages of high raw material conversion rate, few by-products, good selectivity of target products, greenness and environmental protection.
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-
Paragraph 0071; 0072
(2017/01/31)
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- Epoxidation of alkenes and oxidation of sulfides catalyzed by a new binuclear vanadium bis-oxazoline complex
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Bis(oxazoline) ligand, [2,2′-(1,3-phenylene)bis(oxazole-4,2-diyl)]-dimethanol, derived from dicyanobenzene was applied as ligand for complexation with vanadium.The catalyst was characterized by FT-IR, UV-Vis, 1H NMR spectroscopic methods, CHNS, ICP and thermal analyses, and magnetic susceptibility. The catalytic activity of this complex was then studied in the epoxidation of alkenes with TBHP (tert-butyl hydroperoxide), in acetonitrile. The effect of reaction parameters such as kind of solvent and oxygen donors was studied in the epoxidation of cyclooctene. The catalytic activity of this catalyst was also investigated in the oxidation of sulfides with H2O2 in ethanol and the corresponding sulfoxides and sulfones were produced.
- Javadi, Maedeh Moshref,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah
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p. 477 - 485
(2015/02/05)
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- Reduction of aldehydes catalyzed by oxo-rhenium(V) complexes containing heterocyclic ligands
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This work describes the catalytic activity of several oxo-rhenium complexes containing the heterocyclic ligands 2-(2-hydroxy-5-methylphenyl)benzotriazole (Hhmpbta), 2-(2-hydroxyphenyl)benzothiazole (Hhpbt), 2-(2-hydroxyphenyl)benzoxazole (Hhpbo), 2-(2-hydroxyphenyl)-1H-benzimidazole (Hhpbi), isoquinoline-1-carboxylic acid (iqcH), and 4-methoxy-2-quinolinecarboxylic acid (mqcH) in the reduction of 4-nitrobenzaldehyde using phenylsilane as reducing agent. In general, all of the catalysts tested gave good to excellent yields of the 4-nitrobenzyl alcohol. Although, the best result was obtained with the catalytic system PhSiH3/[ReOBr2(hmpbta)(PPh3)] (5 mol %). This system was also applied to the reduction of a large variety of aldehydes, producing the corresponding primary alcohols in good to excellent yields and good chemoselectivity.
- Bernando, Joana R.,Florindo, Pedro R.,Wolff, Mariusz,Machura, Barbara,Fernandes, Ana C.
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p. 414 - 418
(2015/03/30)
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- The catalytic efficiency of Fe-porphyrins supported on multi-walled carbon nanotubes in the heterogeneous oxidation of hydrocarbons and sulfides in water
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Novel recoverable biomimetic catalysts were prepared by the coordinative anchoring of an iron(iii) meso-tetraphenyl porphyrin complex [Fe(TPP)Cl] and some derivatives on the activated multi-walled carbon nanotube (AMWCNT) via hydroxyl functionality (Fe-Por-AMWCNT). The simple heterogeneous catalyst [Fe(TPP)Cl-MWCNT] was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman, FT-IR and UV-vis spectroscopy. The amount of catalyst loading on the nanotubes, was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The thermogravimetric analysis (TGA) demonstrated that the nanocatalyst was thermally stable up to almost 400 °C, exhibiting high thermostability. The epoxidation of olefins and the oxidation of saturated hydrocarbons to the related ketones and also sulfides to the sulfones by aqueous solution of tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO 5, TBAOX) were efficiently enhanced with excellent selectivity under the influence of the separable nanocatalyst with very low catalyst loading. Sulfoxides could also be selectively produced in ethanol, which makes the title methodology a good alternative for both sulfoxide and sulfone production. The separation and recycling of the catalyst and oxidant by-products were simple, effective and economical in this clean oxidation method. The FT-IR, UV-vis and leaching experiments after ten successive cycles showed that the catalyst was most strongly anchored to the MWCNT support. The Royal Society of Chemistry 2014.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh
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p. 1960 - 1969
(2014/06/24)
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- A molybdenum based metallomicellar catalyst for controlled and selective sulfoxidation reactions in aqueous medium
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A surfactant based molybdenum system that exhibits catalytic activity for sulfoxidation reactions of various organic sulfides in aqueous medium has been developed and comprehensively characterized using IR, XRD, NMR, ESI-MS, DLS and TEM. The catalyst showcases remarkable selectivity for the preparation of both sulfoxides and sulfones in the range of good to excellent yields. Furthermore, the catalyst showed a high degree of tolerance towards various sensitive functional groups such as hydroxyl, acetal, aldehyde, amine, imine, oxime, cyano and alkene. the Partner Organisations 2014.
- Chakravarthy, Rajan Deepan,Ramkumar, Venkatachalam,Chand, Dillip Kumar
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p. 2190 - 2196
(2014/04/17)
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- Aqueous heterogeneous oxygenation of hydrocarbons and sulfides catalyzed by recoverable magnetite nanoparticles coated with copper(ii) phthalocyanine
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In this work, a novel magnetically recoverable phthalocyanine catalyst was prepared by immobilization of the Cu(ii) phthalocyanine-tetrasulfonic acid tetrasodium complex (CuPcS) on the silica coated magnetic nanoparticles (Fe 3O4@SiO2, SMNP) via the amine functionality (ASMNP). The epoxidation of olefins and the oxidation of saturated hydrocarbons to the related ketones and also sulfides to the sulfones by an aqueous solution of tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO5, TBAOX) were efficiently enhanced with excellent selectivity under the influence of the catalytic activity of the magnetically separable catalyst. Sulfoxides could also be selectively produced in the mixture of water-ethanol, which makes the title methodology a good alternative for both sulfoxide and sulfone production. The separation and recycling of the catalyst and the reduced form of the oxidant were simple, effective and economical in this clean oxidation method. The FT-IR and leaching experiments after seven successive cycles showed that the catalyst was most strongly anchored to the magnetite nanoparticles.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Naeimi, Atena,Haddad, Reza
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p. 3386 - 3394
(2013/01/16)
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- Nanomagnet-supported partially brominated manganese-porphyrin as a promising catalyst for the selective heterogeneous oxidation of hydrocarbons and sulfides in water
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A novel, magnetically recoverable porphyrin catalyst has been prepared by the coordinative anchoring of the [Mn(Br2TPP)OAc] complex on silica-coated magnetic nanoparticles (Fe3O4@SiO 2, SMNP) through an amine functionality. The heterogeneous catalyst was characterized by powder X-ray diffraction, transmision electron microscopy, scanning electron microscopy, and FTIR spectroscopy. The catalyst loading on the magnetic support was determined by thermogravimetric (TG) analysis and inductively coupled plasma atomic emission spectroscopy. The catalyst nanoparticles were estimated to have a diameter of less than 10 nm. The TG curve demonstrated that the nanocatalyst was thermally stable up to almost 350 °C, exhibiting high thermostability. The epoxidation of olefins and the oxidation of saturated hydrocarbons to the corresponding ketones as well as sulfides to sulfones in an aqueous solution of tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO5, TBAOX) were efficiently enhanced with excellent selectivity under the influence of the magnetically separable catalyst. Sulfoxides could also be selectively produced in a mixture of water and ethanol, which makes the title methodology a good alternative for both sulfoxide and sulfone production. The separation and recycling of the catalyst and the byproduct of the oxidant were simple, effective, and economic in this clean oxidation method. FTIR and leaching experiments after seven successive cycles showed that the catalyst was very strongly anchored to the SMNP support. Copyright
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Farshid, Parisa,Naeimi, Atena
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p. 5515 - 5524
(2013/01/15)
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- Silica-supported molybdenum complex: A novel, selective and reusable organic-inorganic hybrid catalyst for eco-friendly oxidation of sulfides and olefins
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A novel, highly efficient and reusable molybdenum based catalyst has been synthesized by covalent grafting of 2,6-diacetylpyridine-monosalicyloylhydrazone onto functionalized silica followed by complexation with MoO 2(acac)2, and the resulting organic-inorganic hybrid material was found to be highly effective catalyst for oxidation of various sulfides and olefins to their corresponding sulfoxides/sulfones and epoxides, respectively. The catalyst was characterized by elemental analysis (CHN), diffuse reflectance UV-Vis, 13C CPMAS NMR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area analysis, energy dispersive X-ray fluorescence (ED-XRF), Fourier-transform infrared (FT-IR) and atomic absorption spectroscopy (AAS). Mild reaction conditions, high turnover frequency, high selectivity, easy recovery and reusability of the catalyst render the present protocol very useful to address the industrial needs and environmental concerns.
- Sharma,Pandey, Amit,Gulati, Shikha
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- Efficient and highly selective aqueous oxidation of alcohols and sulfides catalyzed by reusable hydrophobic copper (II) phthalocyanine
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A practical innovative method for highly chemoselective oxidation of alcohols to the aldehyde and ketones and sulfides to the sulfones using tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO5) catalyzed by simple water-insoluble copper (II) phthalocyanine (CuPc) in neat water has been developed. Organic co-solvents, surfactants, co-catalyst and hydrophilic auxiliaries were completely missed in this heterogeneous catalytic strategy. The CuPc catalyst and by-product of oxidant (TBAHSO4) could easily be recycled and reused without loss of activity providing readily scalability.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Naeimi, Atena,Salimi, Mehri
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experimental part
p. 230 - 234
(2012/02/14)
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- Synthesis of unsymmetrical 3,4-diaryl-3-pyrrolin-2-ones utilizing pyrrole weinreb amides
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A regiocontrolled synthesis of unsymmetrical 3,4-diaryl-3-pyrrolin-2-ones has been achieved in three steps from 1,2-diaryl-1-nitroethenes with pyrrole-2-carboxamides (pyrrole Weinreb amides) serving as the key linchpin intermediates. Two different methods for the preparation of the requisite nitroalkenes were investigated: (1) modified Henry reaction between arylnitromethanes and arylimines; and (2) Suzuki-Miyaura cross-coupling reaction of 2-aryl-1-bromo-1-nitroethenes with arylboronic acids. Some difficulty was encountered in the preparation of arylnitromethanes, thus leading to the exploration of a cross-coupling strategy that proved more useful. A Barton-Zard pyrrole cyclocondensation reaction between 1,2-diaryl-1-nitroethenes and N-methoxy-N-methyl-2-isocyanoacetamide gave the corresponding pyrrole Weinreb amides, which were then converted into the desired 3-pyrrolin-2-ones in two steps. Overall, this method allowed for the construction of 3,4-diaryl-3- pyrrolin-2-ones with complete regiocontrol of the substituents with respect to the lactam carbonyl. The utility of this synthetic methodology was demonstrated by the preparation of eight unsymmetrical and symmetrical 3,4-diaryl-3-pyrrolin- 2-ones including the N-H lactam analogue of the selective COX-II inhibitor, rofecoxib.
- Greger, Jessica G.,Yoon-Miller, Sarah J. P.,Bechtold, Nathan R.,Flewelling, Scott A.,MacDonald, Jacob P.,Downey, Catherine R.,Cohen, Eric A.,Pelkey, Erin T.
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supporting information; experimental part
p. 8203 - 8214
(2011/12/04)
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- 1,3-Dipolar cycloadditions of acetylenic sulfones in solution and on solid supports
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(Chemical Equation Presented) Several representative acetylenic sulfones were immobilized on a polymer support derived from Merrifield resin by means of ester linkers that were used to couple free carboxylic acid groups on the solid support with benzylic hydroxyl functions on the arylsulfonyl moieties of the acetylenes. Several examples of reversed ester linkers, using Merrifield resin directly, were also successfully prepared. The 1,3-dipolar cycloadditions of the solid-supported acetylenic sulfones were investigated with a series of 1,3-dipoles, including benzyl azide, ethyl diazoacetate, diazomethane, as well as representative nitrile oxides, nitrile imines, nitrile ylides, nitrones, azomethine imines, azomethine ylides, munchnones, and sydnones. In general, analogous cycloadditions were also performed with acetylenic sulfones in solution phase for comparison. The cycloadditions typically afforded good to excellent yields of the desired products in both solution and solid phase, although the latter reactions sometimes required more vigorous conditions. Except in the case of benzyl azide and diazo compounds, where mixtures of regioisomers were obtained, the other 1,3-dipoles reacted with high regioselectivity and afforded essentially unique regioisomers. Cleavage of the products from the resin was smoothly effected by alkaline hydrolysis, while several attempts at reductive desulfonylation with sodium amalgam or samarium diiodide-HMPA resulted in N-O or C-O scission, in addition to cleavage from the polymer. The method provides access to a number of important classes of heterocycles, including variously substituted and functionalized triazoles, pyrazoles, 1,2-oxazoles, pyrroles, as well as their dihydro and bicyclic analogues. The success of the cycloadditions on polymer supports paves the way to future investigations of sequential transformations leading to libraries of useful heterocycles.
- Gao, Detian,Zhai, Huimin,Parvez, Masood,Back, Thomas G.
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p. 8057 - 8068
(2008/12/22)
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- Selective oxidation of sulfides to sulfoxides and sulfones at room temperature using H2O2 and a Mo(VI) salt as catalyst
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Selective oxidation of sulfides to sulfoxides and sulfones is achieved by H2O2 using MoO2Cl2 as the catalyst. Various substituted sulfides having functional groups such as methyl, methoxy, bromo, nitro, alkene, alkyne, alcohol, ester, aldehyde and remarkably an oxime are successfully and selectively oxidized without affecting the sensitive functionalities.
- Jeyakumar, Kandasamy,Chand, Dillip Kumar
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p. 4573 - 4576
(2007/10/03)
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- PHENETANOLAMINE DERIVATIVES
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Compounds of formula (I) and salts, solvates, and physiologically functional derivatives thereof, useful for the prophylaxis or treatment of a clinical condition for which a selective β2-adrenoreceptor agonist is indicated, for example asthma or chronic o
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Page/Page column 51
(2010/02/11)
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- Synthesis of Sulfoxides by the Hydrogen Peroxide Induced Oxidation of Sulfides Catalyzed by Iron Tetrakis(pentafluorophenyl)porphyrin: Scope and Chemoselectivity
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The oxidation of sulfides with H2O2 catalyzed by iron tetrakis(pentafluorophenyl)porphyrin in EtOH is an efficient and chemoselective process. With a catalyst concentration 0.03-0.09% of that of the substrate, sulfoxides are obtained with yields generally around 90-95% of isolated product. With vinyl and allyl sulfides, no epoxidation is observed. With a catalyst concentration between 0.09% and 0.25% of that of the substrate, sulfones are obtained in almost quantitative yield and with the same high chemoselectivity observed in the synthesis of sulfoxides.
- Baciocchi, Enrico,Gerini, Maria Francesca,Lapi, Andrea
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p. 3586 - 3589
(2007/10/03)
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- Selected sulfonyl compounds as anticancer/antimalarial agents
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The synthesis and biological testing of a series of sulfonyl phenols and sulfonyl aryl methyl ethers has revealed that p-methoxyphenyl p-toluenesulfonate is a very selective and effective antimalarial agent which shows pronounced activity against human skin cancer cells. Application of a counter-attack strategy permits the direct preparation of the requisite tosylate ether from the bis(tosylate) of dihydroquinone.
- Langler, Richard F.,Paddock, Robert L.,Thompson, David B.,Crandall, Ian,Ciach, Michelle,Kain, Kevin C.
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p. 1127 - 1133
(2007/10/03)
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- Chromium(VI) oxide catalyzed oxidation of sulfides to sulfones with periodic acid
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A highly efficient and selective oxidation of sulfides to sulfones with periodic acid catalyzed by CrO3 is described. A variety of electron-rich and electron-deficient sulfides were oxidized to sulfones with 2 mol% CrO3 in acetonitrile at room temperature in excellent yields. Sulfides with other readily oxidized functional groups were selectively oxidized to sulfones in high yields with 10 mol% CrO3 in ethyl acetate/acetonitrile at -35 °C.
- Xu, Liang,Cheng, Jie,Trudell, Mark L.
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p. 5388 - 5391
(2007/10/03)
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- Catalytic Conversions in Water. Part 23: Steric Effects and Increased Substrate Scope in the Palladium-Neocuproine Catalyzed Aerobic Oxidation of Alcohols in Aqueous Solvents
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The steric influence of substituents on the 2-and 9-positions of phenanthroline in the (2,9-R2-1,10-phenanthroline)palladium(II)- catalyzed aerobic oxidation of 2-hexanol was investigated by means of high throughput experimentation. (Neocuproine)Pd-(OAc)2 (R=CH 3) was found to be a highly active catalyst for alcohol oxidation in 1:1 water/DMSO mixtures. The catalyst is unique in that it tolerates water, polar co-solvents and a wide variety of functional groups in the alcohol. Turn-over frequencies of > 1500 h-1 were achieved and a series of alcohols was oxidised with 0.1 to 0.5 mol % of catalyst.
- Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Hoogenraad, Marcel,Verspui, Goeran,Sheldon, Roger A.
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p. 1341 - 1352
(2007/10/03)
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- A one-pot multistep approach to α-azido-phosphonate and phosphonothioate diesters: Key intermediates in the synthesis of haptens for the generation of antibody ligases
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A four-step, one-pot synthesis of mixed α-azido-phosphonates and phosphonothioates 12a-d is described. This chemistry has provided a facile route to haptens 6a-b and 7 that have been employed for the elicitation of antibody ligases. Five hapten-specific antibodies have been identified as modest catalysts of a model peptide ligation reaction between thioester 1b and thiol 2 to give the amide product 5. (C) 2000 Elsevier Science Ltd. All rights reserved.
- Harwig, Curtis W.,Hoffman, Timothy Z.,Wentworth, Anita D.,Janda, Kim D.
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p. 915 - 918
(2007/10/03)
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- A Mild, Inexpensive and Practical Oxidation of Sulfides
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Several sulfides have been converted to sulfoxides or sulfones in modest to excellent yields.The oxidant was oxone and the reactions were performed in 12.5percent aqueous acetone and buffered to pH 7.5-8.0 with sodium bicarbonate.
- Webb, Kevin S.
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p. 3457 - 3460
(2007/10/02)
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- Synthesis and antirhinovirus activity of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)-9H-purines
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A series of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)purines was synthesized and tested for antirhinovirus activity. Most of the compounds were synthesized by alkylation of 6-chloro-2-(trifluoromethyl)-9H-purine with the appropriate benzyl halide followed by displacement of the chloro group with dimethylamine. Alternatively, 6-(dimethylamino)-2-(trifluoromethyl)purine was alkylated with the appropriate benzyl halide. Although several different aryl substituents provided compounds with IC50's = 0.03 μM against rhinovirus serotype 1B, no congener was significantly more active than the parent 2. Twenty-three compounds were tested against 18 other serotypes, but none exhibited a uniform profile of activity.
- Kelley,Linn,Selway
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p. 1757 - 1763
(2007/10/02)
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- Correlation pKa - activitee catalitique des thiols dans la reeaction d'hydrolyse de l'aceetate de p-nitropheenyle
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The kinetic study of the hydrolysis of p-nitrophenylacetate in the presence of primary thiols indicates the thiolate anion as the sole catalytic species.Comparison of the true second order constants (kRS-) reveals that purely aliphatic primary thiols behave differently from aromatic α-substituted primary thiols.In the latter group a correlation can be established between the true second order rate constants and the pKSH values by means of the Broensted equation log kRS- = βpKSH + C, with β equal to 0.40 and C equal to -0.85.
- Brembilla, Alain,Roizard, Denis,Schoenleber, Jacqueline,Lochon, Pierre
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p. 2330 - 2336
(2007/10/02)
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