- Synthesis of phosphonate derivatives of 2,3-dihydroindene
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Simple and convenient procedures for the synthesis of derivatives of 2,3-dihydroinden-2-ylphosphonic acid are developed. The reaction strategies utilize both functionalization of the already existing 2,3-dihydroindene skeleton and an annulation reaction starting from readily available o-disubstituted benzene derivatives.
- Prokopowicz, Monika,M?ynarz, Piotr,Kafarski, Pawe?
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- One-pot synthesis of 4-alkoxybenzo[c]thiophenes
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The reaction of N-bromosuccinimide with 4,5,6,7-tetrahydrobenzo[c]thiophen-4-ones in the presence of 2,2′-azo-bis-isobutyronitrile followed by heating under reflux with different alcohols produces 4-alkoxybenzo[c]thiophenes in good yield.
- Akbarzadeh, Tahmineh,Shafiee, Abbas
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- Non-linear, cata-Condensed, Polycyclic Aromatic Hydrocarbon Materials: A Generic Approach and Physical Properties
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A generic approach to the regiospecific synthesis of halogenated polycyclic aromatics is made possible by the one- or two-directional benzannulation reactions of readily available (ortho-allylaryl)trichloroacetates (the "BHQ" reaction). Palladium-catalyse
- Haire, Barnaby T.,Heard, Kane W. J.,Little, Mark S.,Parry, Adam V. S.,Raftery, James,Quayle, Peter,Yeates, Stephen G.
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- A Method for the Catalytic Enantioselective Synthesis of Chiral α-Azido and α-Amino Ketones from Racemic α-Bromo Ketones, and Its Generalization to the Formation of Bonds to C, O, and S
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A new and practical method has been developed for the transformation of racemic α-bromo ketones to chiral α-azido and α-amino ketones with high enantioselectivity using phase transfer, ion-pair mediated reactions with a recoverable chiral quaternary salt (10 mol %) as catalyst in fluorobenzene-water. The process has been generalized to a variety of other attachments including of C, O, S, and NHR.
- Da Silva Gomes, Roberto,Corey
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- Studies on bromination of active methylene by a mixture of hydrobromic acid and hydrogen peroxide (or TBHP)
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Studies on bromination of active methylene with a mixture of hydrogen peroxide or tert-butylhydroperoxide (TBHP) and hydrobromic acid are discussed. Substituted acetophenones, benzocyclic ketones provide α-bromo-keto compounds in high yields under this re
- Tillu, Vasudha H.,Shinde, Popat D.,Bedekar, Ashutosh V.,Wakharkar, Radhika D.
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- Acridine Orange Hemi(Zinc Chloride) Salt as a Lewis Acid-Photoredox Hybrid Catalyst for the Generation of α-Carbonyl Radicals
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A readily accessible organic-inorganic hybrid catalyst is reported for the reductive fragmentation of α-halocarbonyl compounds. The robust hybrid catalyst is a self-stabilizing combination of ZnCl2 Lewis acid and acridine orange as the photoactive organic dye. Mechanistic specifics of this hybrid catalyst have been studied in detail using both photophysical and electrochemical experiments. A systematic study enabled the discovery of the appropriate Lewis acid for the effective LUMO stabilization of α-halocarbonyl compounds and thereby lowering of reduction potential within the range of a standard organic dye. This strategy resolves the issues like dehalogenative hydrogenation or homo-coupling of alkyl radicals by guiding the photoredox cycle through an oxidative quenching pathway. The cooperativity between the photoactive organic dye and the Lewis acid counterparts empowers functionalization with a wide range of coupling partners through efficient and controlled generation of alkyl radicals and serves as an appropriate alternative to the expensive late transition metal-based photocatalysts. To demonstrate the application potential of this cooperative catalytic system, four different synthetic transformations of α-carbonyl bromides were explored with broad substrate scopes.
- Das, Sanju,Mandal, Tanumoy,De Sarkar, Suman
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supporting information
p. 755 - 765
(2021/12/10)
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- Highly Deformed o-Carborane Functionalised Non-linear Polycyclic Aromatics with Exceptionally Long C?C Bonds
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The effect of substituting o-carborane into the most sterically hindered positions of phenanthrene and benzo(k)tetraphene is reported. Synthesised via a Bull–Hutchings–Quayle benzannulation, the crystal structures of these non-linear acenes exhibited the highest aromatic deformation parameters observed for any reported carborane compound to date, and among the largest carboranyl C?C bond length of all organo-substituted o-carboranes. Photoluminescence studies of these compounds demonstrated efficient intramolecular charge-transfer, leading to aggregation induced emission properties. Additionally, an unusual low-energy excimer was observed for the phenanthryl compound. These are two new members of the family of carborane-functionalised non-linear acenes, notable for their peculiar structures and multi-luminescent properties.
- Marsh, Adam V.,Little, Mark,Cheetham, Nathan J.,Dyson, Matthew J.,Bidwell, Matthew,White, Andrew J. P.,Warriner, Colin N.,Swain, Anthony C.,McCulloch, Iain,Stavrinou, Paul N.,Heeney, Martin
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supporting information
p. 1970 - 1975
(2020/12/25)
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- Annulation reaction of cyclic pyridinium ylides with: In situ generated azoalkenes for the construction of spirocyclic skeletons
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Two new types of cyclic pyridinium ylides were designed and further used in reactions with azoalkenes to access structurally diverse spirocyclic compounds. A range of spiropyrazoline oxindoles could be smoothly obtained in up to 99% yield via a [4 + 1] annulation process with oxindole 3-pyridinium ylides as C1 synthons. Similarly, a series of spiropyrazoline indanones could be prepared with indanone 2-pyridinium ylides as C1 synthons. This work represents the first example of cyclic pyridinium ylides as C1 synthons for the efficient construction of spirocyclic compounds.
- Quan, Bao-Xue,Yuan, Wei-Cheng,Zhang, Ming-Liang,Zhang, Xiao-Mei,Zhao, Jian-Qiang,Zhou, Ming-Qiang,Zhuo, Jun-Rui
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supporting information
p. 1886 - 1891
(2020/03/23)
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- Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: Towards the design of photoswitchable sirtuin inhibitors
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The use of light as an external trigger to change ligand shape and as a result its bioactivity, allows the probing of pharmacologically relevant systems with spatiotemporal resolution. A hetero-stilbene lead resulting from the screening of a compound that was originally designed as kinase inhibitor served as a starting point for the design of photoswitchable sirtuin inhibitors. Because the original stilbenoid structure exerted unfavourable photochemical characteristics it was remodelled to its heteroarylic diazeno analogue. By this intramolecular azologization, the shape of the molecule was left unaltered, whereas the photoswitching ability was improved. As anticipated, the highly analogous compound showed similar activity in its thermodynamically stable stretched-out (E)-form. Irradiation of this isomer triggers isomerisation to the long-lived (Z)-configuration with a bent geometry causing a considerably shorter end‐to‐end distance. The resulting affinity shifts are intended to enable real‐time photomodulation of sirtuins in vitro.
- Grathwol, Christoph W.,W?ssner, Nathalie,Swyter, S?ren,Smith, Adam C.,Tapavicza, Enrico,Hofstetter, Robert K.,Bodtke, Anja,Jung, Manfred,Link, Andreas
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supporting information
p. 2170 - 2183
(2019/09/30)
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- The Electrophilic Fluorination of Enol Esters Using SelectFluor: A Polar Two-Electron Process
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The reaction of enol esters with SelectFluor is facile and leads to the corresponding α-fluoroketones under mild conditions and, as a result, this route is commonly employed for the synthesis of medicinally important compounds such as fluorinated steroids. However, despite the use of this methodology in synthesis, the mechanism of this reaction and the influence of structure on reactivity are unclear. A rigorous mechanistic study of the fluorination of these substrates is presented, informed primarily by detailed and robust kinetic experiments. The results of this study implicate a polar two-electron process via an oxygen-stabilised carbenium species, rather than a single-electron process involving radical intermediates. The structure–reactivity relationships revealed here will assist synthetic chemists in deploying this type of methodology in the syntheses of α-fluoroketones.
- Wood, Susanna H.,Etridge, Stephen,Kennedy, Alan R.,Percy, Jonathan M.,Nelson, David J.
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supporting information
p. 5574 - 5585
(2019/03/21)
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- Highly Enantioselective Synthesis of Fused Tri- and Tetrasubstituted Aziridines: aza-Darzens Reaction of Cyclic Imines with α-Halogenated Ketones Catalyzed by Bifunctional Phosphonium Salt
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The first enantioselective aza-Darzens reaction of cyclic imines with α-halogenated ketones was realized under mild reaction conditions by using amino-acid-derived bifunctional phosphonium salts as phase-transfer promoters. A variety of structurally dense tri- and tetrasubstituted aziridine derivatives, containing benzofused heterocycles as well as spiro-structures, were readily synthesized in high yields with excellent diastereo- and enantioselectivities (up to >20:1 d.r. and >99.9 % ee). The highly functionalized aziridine products could be easily transformed into different classes of biologically active compounds.
- Pan, Jianke,Wu, Jia-Hong,Zhang, Hongkui,Ren, Xiaoyu,Tan, Jian-Ping,Zhu, Lixiang,Zhang, Hong-Su,Jiang, Chunhui,Wang, Tianli
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supporting information
p. 7425 - 7430
(2019/05/10)
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- Divergent synthesis of N-heterocycles by Pd-catalyzed controllable cyclization of vinylethylene carbonates
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Here, we report a palladium-catalyzed controllable cyclization of vinyl ethylene carbonates that proceeds through formal migration [2+3] and [5+2] cycloadditions, respectively, under mild conditions. The transformation described here affords a series of synthetically versatile 5,7-membered N-heterocycles which are found in natural products and pharmaceuticals with biological and medicinal properties.
- Yang, Yuwen,Yang, Weibo
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supporting information
p. 12182 - 12185
(2018/11/21)
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- Diversity-Orientated Stereoselective Synthesis through Pd-Catalyzed Switchable Decarboxylative C?N/C?S Bond Formation in Allylic Surrogates
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Switchable catalytic transformation of reactants can be a powerful approach towards diversity-orientated synthesis from easily available molecular synthons. Herein, an endogenous ligand-controlled, Pd-catalyzed allylic substitution allowing for either selective C?N or C?S bond formation using vinylethylene carbonates (VECs) and N-sulfonylhydrazones as coupling partners has been developed. This versatile methodology provides a facile, divergent route for the highly chemo- and stereoselective synthesis of functional allylic sulfones or sulfonohydrazides. The newly developed protocol features wide substrate scope (nearly 80 examples), broad functional group tolerance, and potential for the late-stage functionalization of bioactive compounds. The isolation and crystallographic analysis of a catalytically competent π-allyl Pd complex suggests that the pathway leading to the allylic products proceeds through a different manifold as previously proposed for the functionalization of VECs with nucleophiles.
- Deng, Lei,Kleij, Arjan W.,Yang, Weibo
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supporting information
p. 19156 - 19161
(2018/11/30)
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- Efficient sulfonylation of ketones with sodium sulfinates for the synthesis of β-keto sulfones
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The oxidative sulfonylation of ketones with sodium sulfinates as the sulfone source and DMSO as the oxidant is reported. A series of β-keto sulfones were obtained in good to excellent yields. The advantages of this efficient protocol include the low cost of DMSO and HBr, and a broad scope.
- Deng, Siqi,Liang, En,Wu, Yinrong,Tang, Xiaodong
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supporting information
p. 3955 - 3957
(2018/09/27)
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- A new and versatile one-pot strategy to synthesize alpha-bromoketones from secondary alcohols using ammonium bromide and oxone
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A new, efficient and green protocol for the one-pot synthesis of α-bromoketones from secondary alcohols using cheap, air stable and non-toxic reagents such as NH4Br and oxone has been developed. This reaction proceeds via two consecutive steps such as oxidation of secondary alcohols and oxidative bromination of in situ generated ketones.
- Rammurthy, Banothu,Swamy, Peraka,Naresh, Mameda,Srujana, Kodumuri,Durgaiah, Chevella,Krishna Sai, Gajula,Narender, Nama
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p. 3710 - 3714
(2017/07/12)
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- Catalytic dehydrogenative dual functionalization of ethers: Dealkylation-oxidation-bromination accompanied by C-O bond cleavage: Via aerobic oxidation of bromide
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Catalytic dehydrogenative dual functionalization (DDF) of ethers via oxidation, dealkylation, and α-bromination by the aerobic oxidation of bromide was developed to obtain the corresponding α-bromo ketones in high yields. In particular, the reaction of substituted tetrahydrofurans as cyclic ethers provided 3,3-dibromo tetrahydrofuran-2-ols in high yields selectively through the double α-bromination.
- Moriyama, Katsuhiko,Hamada, Tsukasa,Nakamura, Yu,Togo, Hideo
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supporting information
p. 6565 - 6568
(2017/07/10)
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- A 3 - bromo - 1, 3, 4, 5 - tetrahydro - 2 H - 1 - benzazepine - 2 - one preparation method
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The invention discloses a preparation method of 3-bromo-1,3,4,5-tetrahydro-2H-benzazepine-2-keto. The preparation method comprises the following stages: alpha-tetralone preparation stage, 2-bromo-3,4-dihydro-N-hydroxy-(2H)-naphthalimide preparation stage and 3-bromo-1,3,4,5-tetrahydro-2H-1-benzazepine-2-keto, wherein the alpha-tetralone preparation stage comprises the following steps: after mixing gamma-butyrolactone, benzene and aluminum chloride anhydrous, raising the temperature to be 60-90 DEG C, and preserving the temperature for reaction for 5-30 hours; after the reaction is finished, performing hydrolysis, layering and washing on 25 parts of 6% hydrochloric acid solution until neutral; and then distilling to remove excessive benzene, and performing high vacuum rectification to obtain alpha-tetralone. Then, the finished product is finally prepared through a bromination reaction, an oximation reaction and a beckmann rearrangement reaction, the purity of the finished product is high, and the yield is as high as more than 90%. Moreover, the production technology is simple, the production cost is low, and the pollution is little.
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- A Simple and Efficient Method for the Preparation of α-Halogenated Ketones Using Iron(III) Chloride and Iron(III) Bromide as Halogen Sources with Phenyliodonium Diacetate as Oxidant
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α-Halogenated ketones are both unique structure moieties existing in biologically natural products and valuable synthetic intermediates for the preparation of functional molecules. An efficient and scalable method for the preparation of α-halogenated ketone using iron (III) chloride and iron (III) bromide as halogen sources with phenyliodonium diacetate as oxidant has been developed, featuring mild reaction conditions, environmentally friendly reagents, and wide substrate scope. Notably, the three-step synthesis of drug prasugrel was achieved using this developed method as a key step with 30% yield on gram-scale. Additionally, the reaction mechanism involving chloride cation was proposed based on some preliminary control experiments. (Figure presented.).
- Tang, Shi-Zhong,Zhao, Wenshuang,Chen, Tao,Liu, Yang,Zhang, Xiao-Ming,Zhang, Fu-Min
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supporting information
p. 4177 - 4183
(2017/12/18)
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- 2-AMINO-1,3,4-THIADIAZINE AND 2-AMINO-1,3,4-OXADIAZINE BASED ANTIFUNGAL AGENTS
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The invention provides a compound which is a diazine of formula (I) or a tautomer thereof, or a pharmaceutically acceptable salt thereof, for use as an antifungal agent: (I) wherein X, N', C', A and E are as defined herein. The invention also provides a compound of Formula (I) as defined herein.
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Page/Page column 53; 54
(2017/02/09)
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- Oxidative bromination reactions in aqueous media by using Bu4NBr/TFA/H2O2 system
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Metal-free oxidative bromination reactions in aqueous media were performed using tetrabutylammonium bromide, trifluoroacetic acid, and hydrogen peroxide under mild conditions. Oxidative bromination reaction of alkenes was found to afford the corresponding vic-bromides. Furthermore, this oxidative bromination system is applicable to the oxidative bromination of alkynes, arenes, and 3,4-dihydronaphthalen-1(2H)-one. A gram-scale bromination reaction was also performed successfully.
- Moriuchi, Toshiyuki,Fukui, Yasuhiro,Sakuramoto, Takashi,Hirao, Toshikazu
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supporting information
p. 1708 - 1710
(2017/11/23)
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- Iodine(III)-Mediated Oxidative Hydrolysis of Haloalkenes: Access to α-Halo Ketones by a Release-and-Catch Mechanism
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An unprecedented iodine(III)-mediated oxidative transposition of vinyl halides has been accomplished. The products obtained, α-halo ketones, are useful and polyvalent synthetic precursors. There are only a handful of reported examples of the direct conversion of vinyl halides to their corresponding α-halo carbonyl compounds. Insights into the mechanism and demonstration that this synthetic transformation can be done under enantioselective conditions are reported.
- Jobin-Des Lauriers, Antoine,Legault, Claude Y.
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supporting information
p. 108 - 111
(2016/01/15)
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- 1,3-Dibromo-5,5-dimethylhydantoin (DBH) mediated one-pot syntheses of α-bromo/amino ketones from alkenes in water
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α-Bromo ketones are versatile intermediates of high practical utility. Traditional approaches to these compounds are restricted to a relatively hazardous/complex reagent combination, a long reaction time, the use of non-environmentally friendly solvents, or a limited substrate scope. Herein, we describe the development of a new methodology for the preparation of α-bromo ketones from alkenes using 1,3-dibromo-5,5-dimethylhydantoin (DBH) as a bromine source and an oxidant simultaneously. This easy to carry out two-step one-pot protocol proceeds in water and provides high yield of a great variety of α-bromo ketones. Addition of an amine to the intermediate α-bromo ketone further enables the preparation of α-amino ketones in a one-pot sequence.
- Xu, Senhan,Wu, Ping,Zhang, Wei
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p. 11389 - 11395
(2016/12/18)
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- Copper nitrate-catalyzed α -bromination of aryl ketones with hydrobromic acid
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An efficient method for α-bromination of aryl ketones, using the combination of molecular oxygen and aqueous hydrobromic acid as a brominating agent in the presence of the copper nitrate, has been developed. This catalytic system, which uses cheap and readily available reactants, shows good atom economy with water as the only by-product.
- Wang, Jianqiang,Wang, Xiaolei,Niu, Zong-Qiang,Wang, Jian,Zhang, Man,Li, Jing-Hua
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p. 165 - 168
(2016/02/23)
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- Iminolactones as tools for inversion of the absolute configuration of α-amino acids and as inhibitors of cancer cell proliferation
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A library of iminolactones was prepared by esterification of several 2-hydroxyketones with a number of N-protected d- and l-α-amino acids. Some of the hydroxyketones were of terpenoid origin while others were obtained via synthesis. After N-deprotection of the intermediate esters, the free amines spontaneously underwent condensation with the ketone to form iminolactones. Esters of (1S,2S,5S)-2-hydroxypinan-3-one with both d- and l-α-amino acids were partially epimerized at the α-carbon atom to give a diastereomeric ester mixture. Only iminolactones of l-amino acids were formed after cyclization of (1S,2S,5S)-2-hydroxypinan-3-one, and correspondingly only d-amino acid iminolactones were formed after reaction with (1R,2R,5R)-2-hydroxypinan-3-one. The protocol thus enables inversion of the absolute configuration of amino acids. Some members of the prepared library of iminolactones displayed significant anti-proliferative effects toward three cancer cell lines (EL4, MCF7, PC3) with insignificant effect on non-malign cell lines (McCoy, MCF10A, NIH3T3). Thus, iminolactones appear to be potential lead structures for preparation of drugs selectively affecting proliferation of malign cell lines.
- Jensen, Christina Mern?e,Chow, Hsiao-Qing,Chen, Ming,Zhai, Lin,Frydenvang, Karla,Liu, Huizhen,Franzyk, Henrik,Christensen, S?ren Br?gger
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p. 118 - 133
(2016/05/02)
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- Kinetic Resolution Driven Diastereo- and Enantioselective Synthesis of cis-β-Heteroaryl Amino Cycloalkanols by Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation
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The utility of tethered Ru-TsDPEN catalyst has been demonstrated for the asymmetric transfer hydrogenation of rac-α-heteroaryl amino cycloalkanones to construct biologically important cis-β-heteroaryl amino cycloalkanols with two contiguous chiral centers
- Vyas, Vijyesh K.,Bhanage, Bhalchandra M.
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supporting information
p. 6436 - 6439
(2016/12/23)
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- Highly enantioselective hydrogenation of o-alkoxy tetrasubstituted enamides catalyzed by a Rh/(R, S)-josiphos catalyst
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Rh/(R,S)-JosiPhos complex-catalyzed asymmetric hydrogenation of o-alkoxy tetrasubstituted enamides has been achieved, and it furnished a set of β-amino alcohol analogues in high yields and excellent enantiomeric excesses (>99% conversion, up to 99% ee).This method provides valuable chiral building blocks in chiral pharmaceuticals and useful motifs for catalysts.
- Meng, Jingjing,Gao, Min,Lv, Hui,Zhang, Xumu
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supporting information
p. 1842 - 1845
(2015/04/27)
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- A Convergent Radical Based Route to Trifluoromethyl Ketones and to α,β-Unsaturated Trifluoromethyl Ketones
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A convergent synthesis of trifluoromethyl ketones and α,β-unsaturated trifluoromethyl ketones is described, starting with aliphatic iodides and dithiocarbonates (xanthates) and exploiting both the α- and β-fragmentations of a sulfonyl radical. The transfo
- Anthore, Lucile,Zard, Samir Z.
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supporting information
p. 3058 - 3061
(2015/06/30)
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- Desulfonylative Methenylation of β-Keto Sulfones
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A one-step strategy for the synthesis of α-methenyl ketones from β-keto sufones is reported. Success of the methodology is elaborated for the synthesis of chromanones and isoflavanones in one-step.
- Pandey, Ganesh,Vaitla, Janakiram
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supporting information
p. 4890 - 4893
(2015/10/12)
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- PPh3·HBr-DMSO mediated expedient synthesis of γ-substituted β,γ-unsaturated α-ketomethylthioesters and α-bromo enals: Application to the synthesis of 2-methylsulfanyl-3(2 H)-furanones
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An efficient chemoselective general procedure for the synthesis of γ-substituted β,γ-unsaturated α-ketomethylthioesters from α,β-unsaturated ketones has been achieved through an unprecedented PPh3·HBr-DMSO mediated oxidative bromination and Kornblum oxidation sequence. The newly developed reagent system serves admirably for the synthesis of α-bromoenals from enals. Furthermore, AuCl 3-catalyzed efficient access to 3(2H)-furanones from the above intermediates under extremely mild conditions are described. Copyright
- Mal, Kanchan,Sharma, Abhinandan,Maulik, Prakas R.,Das, Indrajit
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supporting information
p. 662 - 667
(2014/01/23)
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- Synthesis of phenacyl bromides via K2S2O 8-mediated tandem hydroxybromination and oxidation of styrenes in water
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Non-transition metal-catalyzed synthesis of phenacyl bromides was achieved through K2S2O8-mediated tandem hydroxybromination and oxidation of styrenes. The advantages of this reaction are its excellent functional group compatibility, mild reaction conditions (60 °C) and use of pure water as reaction medium. Based upon experimental observations, a plausible reaction mechanism is proposed.
- Jiang, Qing,Sheng, Wenbing,Guo, Cancheng
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p. 2175 - 2179
(2013/09/24)
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- Metal-free desulfonylation reaction through visible-light photoredox catalysis
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The desulfonylation of β-arylketosulfones has been achieved in good to excellent yields by using 3-W blue LEDs light, 1 mol-% organic dye eosin Y bis(tetrabutylammonium salt) as photocatalyst, and diisopropylethylamine as reducing agent. Mechanistic studies demonstrate that oxidative quenching of the excited eosin Y by β-arylketosulfones plays a crucial role in the present photoredox catalytic cycle. Reductive desulfonylation is essential to enable to use of a sulfone as an auxiliary group. For reductive removal of sulfones, highly aggressive metal-containing reducing agents and harsh reaction conditions are often employed. In this paper, metal-free desulfonylation of β-arylketosulfones can be achieved efficiently at room temperature under visible-light irradiation.
- Yang, Deng-Tao,Meng, Qing-Yuan,Zhong, Jian-Ji,Xiang, Ming,Liu, Qiang,Wu, Li-Zhu
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p. 7528 - 7532
(2013/12/04)
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- Oxidative bromination of ketones using ammonium bromide and oxone
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A highly efficient, environmentally safe and economic method for selective α-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and β-keto esters and α,α-dibromination of 1,3-diketones and β-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone as an oxidant. The reaction proceeds at ambient temperature and yields range from moderate to excellent. Bromination of unsymmetrical ketones takes place at the less substituted α-position predominantly. Aromatisation of tetralones is also carried out with this reagent system.
- MacHarla, Arun Kumar,Chozhiyath Nappunni, Rohitha,Marri, Mahender Reddy,Peraka, Swamy,Nama, Narender
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supporting information; experimental part
p. 191 - 195
(2012/01/17)
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- [Cu(dap)2Cl] as an efficient visible-light-driven photoredox catalyst in carbon-carbon bond-forming reactions
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Copper sees the light of day: [Cu(dap)2Cl] proved to be an excellent photoredox catalyst for atom-transfer radical addition reactions, as well as for allylation reactions (see scheme), providing an attractive alternative to commonly used iridium- and ruthenium-based catalysts. Copyright
- Pirtsch, Michael,Paria, Suva,Matsuno, Taisuke,Isobe, Hiroyuki,Reiser, Oliver
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supporting information; experimental part
p. 7336 - 7340
(2012/09/08)
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- Visible-light photoredox catalysis: Dehalogenation of vicinal dibromo-, α-halo-, and α,α-dibromocarbonyl compounds
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vic-Dibromo-, α-halo-, or α,α-dibromocarbonyl compounds can be efficiently dehalogenated using catalytic tris(2,2′-bipyridyl) ruthenium dichloride (Ru(bpy)3Cl2) in combination with 1,5-dimethoxynaphthalene (DMN) and ascorbate as sacrificial electron donor. For this process, a visible light promoted photocatalytic cycle is proposed that involves the reduction of carbon halogen bonds via free radical intermediates.
- Maji, Tapan,Karmakar, Ananta,Reiser, Oliver
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supporting information; experimental part
p. 736 - 739
(2011/03/20)
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- N-Halosuccinimide/SiCl4 as general, mild and efficient systems for the α-monohalogenation of carbonyl compounds and for benzylic halogenation
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Combinations of N-halosuccinimide and tetrachlorosilane in acetonitrile were found to be efficient systems for the selective α-monohalogenation of carbonyl compounds as well as for benzylic halogenation under mild conditions.
- Salama, Tarek A.,Novák, Zoltán
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experimental part
p. 4026 - 4029
(2011/08/09)
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- Synthesis of quinoxaline analogues
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Substituted tricyclic or tetracyclic quinoxalines, tricyclic pyridoquinoxalines and bis-quinoxalines were synthesized in high yields starting from cyclic ketones by the -bromination of cyclic ketones with N-bromosuccinimide (NBS) followed by condensation of the resulting -bromo ketones with 1,2-diaminobenzene, 3,4-diaminopyridine, or 3,3-diaminobenzidine. Georg Thieme Verlag Stuttgart New York.
- Chang, Meng-Yang,Lee, Tein-Wei,Hsu, Ru-Ting,Yen, Tzu-Lin
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experimental part
p. 3143 - 3151
(2011/10/30)
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- SYNTHESIS OF SUBSTITUTED TETRAHYDROINDENYL COMPLEXES
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This invention relates to the synthesis of substituted tetrahydroindenyls and the use of the synthesised complexes in the homo- and co-polymerisation of ethylene and alpha-olefins.
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Page/Page column 9-11
(2010/08/04)
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- Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
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A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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experimental part
p. 4429 - 4439
(2009/10/09)
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- An expedient protocol for conversion of olefins to α-bromo/iodoketones using IBX and NBS/NIS
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A variety of olefins have been shown to undergo conversion to the corresponding α-bromo/iodoketones when reacted with NBS/NIS and IBX in DMSO at room temperature. While the reaction is found to occur rapidly with e-rich arylolefins leading to the corresponding haloketones in 65-95% yields in 0.3-3.0 h, those containing e-withdrawing groups are found to yield diketones concomitantly, such that the latter are the exclusive products over extended duration of the reactions.
- Moorthy, Jarugu Narasimha,Senapati, Kalyan,Singhal, Nidhi
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experimental part
p. 2493 - 2496
(2009/08/17)
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- Cu(OTf)2-catalyzed α-halogenation of ketones with 1,3-dichloro-5,5'-dimethylhydantoin and N-bromosuccinimide
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Copper(II) triflate catalyses efficiently the α-halogentaion of aryl or alkyl ketones with l.3-diehloro-5.5'-dimethylhydantoin and N-bromosuccinimde to give the corresponding α,α-dichloroketones and α-bromoketones in high yield with excellent product selectivity.
- Jagdale, Arun R.,Chouthaiwale, Pandurang V.,Sudalai, Arumugam
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experimental part
p. 1424 - 1430
(2010/02/28)
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- A modular synthesis of highly substituted imidazolium salts
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A versatile and modular one-pot method for the preparation of differently substituted symmetrical and unsymmetrical imidazolium salts is reported, and 19 examples are given. In the key step, readily available formamidines and α-halo ketones are coupled to give imidazolinium salts 3, followed by imidazolium salt formation by acylation-induced elimination. For many substitution patterns of the imidazolium salt products, this efficient strategy compares favorably with well-known processes in terms of yield, ease of synthesis, and robustness.
- Hirano, Keiichi,Urban, Slawomir,Wang, Congyang,Glorius, Frank
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supporting information; experimental part
p. 1019 - 1022
(2009/07/18)
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- Halogenation of ketones with N-halosuccinimides under solvent-free reaction conditions
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Several aryl substituted ketones, cyclic ketones, 1,3-diketones and a β-ketoamide were halogenated with N-halosuccinimides under solvent-free reaction conditions (SFRC) at various temperatures (20-80 °C), whereas less enolized ketones required the presence of an acid catalyst (p-toluenesulfonic acid, PTSA). Bromination of substituted acetophenones obeys first order kinetics v=kBr[ketone] and the following correlation with the keto-enol equilibrium constant: log kBr=0.3pKE+C1, less enolized substrates being more reactive; the moderate positive charge developed in the rate determining step was confirmed by the Hammett correlation (ρ=-0.5). On the other hand, in cyclic ketones an opposite relation was observed: log kBr=-0.6pKE+C2, indicating higher reactivity of substrates with higher enolization constant (KE). The important role of the nature of the solvent (MeCN, MeOH) in preorganization of the ketone-NBS-PTSA mixture prior to SFRC bromination was found.
- Pravst, Igor,Zupan, Marko,Stavber, Stojan
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p. 5191 - 5199
(2008/09/21)
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- A convenient one-pot synthesis of thiazol-2-imines: application in the construction of pifithrin analogues
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For the first time a reaction intermediate has been isolated giving further insight into the mechanism of thiazol-2-imine formation. The first step of the reaction requires a basic medium, while the second step is an acid mediated E1 elimination reaction. An efficient one-pot synthesis of substituted thiazol-2-imines have been achieved by the condensation of carbonyl compounds with thioureas and 1,3-disubstituted thioureas using 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT). Unsymmetrical 1,3-disubstituted thioureas give regioselective products with symmetrical ketones, which are mainly governed by the pKas of NH protons of thiourea, whereas symmetrical 1,3-disubstituted thioureas give regioselective products with symmetrical carbonyl compounds owing to the regioselective bromination of ketones. The methodology is extended to access novel neurodegenerative drug candidate pifithrin-α analogues in good yields in shorter reaction time. This method is simple, versatile and is applicable for different 1,3-disubstituted thioureas as well as a range of carbonyl compounds.
- Murru, Siva,Singh,Kavala, Veerababurao,Patel, Bhisma K.
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p. 1931 - 1942
(2008/09/17)
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- 2-Aminotetralones: Novel inhibitors of MurA and MurZ
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Several 2-aminotetralones were identified as novel inhibitors of the bacterial enzymes MurA and MurZ. A number of these inhibitors demonstrated antibacterial activity against Staphylococcus aureus and Escherichia coli with MICs in the range 8-128 μg/ml. B
- Dunsmore, Colin J.,Miller, Keith,Blake, Katy L.,Patching, Simon G.,Henderson, Peter J.F.,Garnett, James A.,Stubbings, William J.,Phillips, Simon E.V.,Palestrant, Deborah J.,Angeles, Joseph De Los,Leeds, Jennifer A.,Chopra, Ian,Fishwick, Colin W.G.
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p. 1730 - 1734
(2008/12/20)
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- Ionic liquid promoted selective debromination of α-bromoketones under microwave irradiation
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The debromination of α-bromoketones with an easily accessible ionic liquid, 1-methyl-3-pentylimidazolium tetrafluoroborate, [pmIm]BF4 under microwave irradiation has been investigated. By controlling the reaction time gem-α-dibromoketones are selectively debrominated to either monobromo or debromoketones. The α-monobromo- and α-monoiodoketones are dehalogenated while the corresponding chloroketones remain inert. The activated vic-bromoacetates are converted to the corresponding (E)-alkenes by the same procedure. These reactions do not require any organic solvent, any metal or any conventional reducing agent. The ionic liquid works here as catalyst as well as reaction medium and is recycled without any appreciable loss of its catalytic efficiency.
- Ranu, Brindaban C.,Chattopadhyay, Kalicharan,Jana, Ranjan
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p. 155 - 159
(2007/10/03)
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- Rapid and catalyst-free α-halogenation of ketones using N-halosuccinamides in DMSO
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α-Halogenation of various carbonyl compounds such as β-keto-esters, cyclic ketones, and lactams with N-halosuccinamides (NBS, NCS, NIS) in the presence of DMSO proceeded very smoothly to give the corresponding α-monohalogenated products in good to excellent yields with high selectivity under catalyst-free conditions. Copyright Taylor & Francis Group, LLC.
- Sreedhar,Reddy, P. Surendra,Madhavi
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p. 4149 - 4156
(2008/03/13)
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- Halogenation of carbonyl compounds by an ionic liquid, [AcMIm]X, and Ceric Ammonium Nitrate (CAN)
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An ionic liquid, acetylmethylimidazolium halide ([AcMIm]X), in combination with ceric ammonium nitrate promotes halogenations of a wide variety of ketones and 1,3-keto esters at the ?-position. The ionic liquid acts here as reagent as well as reaction medium, and thus the reaction does not require any organic solvent or conventional halogenating agent. The reaction is completely arrested when the radical quencher TEMPO is used. A plausible radical mechanism is also suggested. CSIRO 2007.
- Ranu, Brindaban C.,Adak, Laksmikanta,Banerjee, Subhash
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p. 358 - 362
(2008/02/13)
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- Efficient α-chlorination and α-bromination of carbonyl compounds using N-halosuccinimides/UHP in ionic liquid
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A facile and efficient method for the α-halogenation of carbonyl compounds utilizing N-halosuccinimides (NXS) in the presence of urea-hydrogen peroxide (UHP) in [bmim]BF4 has been newly developed. Copyright Taylor & Francis Group, LLC.
- Lee, Jong Chan,Park, Hyun Jung
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- Photochemical α-bromination of ketones using N-bromosuccinimide: a simple, mild and efficient method
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Aromatic and aliphatic carbonyl compounds undergo facile bromination with N-bromosuccinimide under UV-vis irradiation to give the corresponding α-brominated ketones in good yields, at low temperatures (30 °C), without any catalyst, catalyst support or radical initiator and within a short time.
- Arbuj, Sudhir S.,Waghmode, Suresh B.,Ramaswamy
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p. 1411 - 1415
(2007/10/03)
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- A green approach for efficient α-halogenation of β-dicarbonyl compounds and cyclic ketones using N-halosuccinimides in ionic liquids
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Room temperature ionic liquids (ILs) are used as a green recyclable reaction media for the α-monohalogenation of 1,3-diketones, β-keto-esters and cyclic ketones with N-halosuccinimides in excellent yields in the absence of a catalyst. The recovered ionic liquid was reused five to six times with consistent activity.
- Meshram,Reddy,Vishnu,Sadashiv,Yadav
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p. 991 - 995
(2007/10/03)
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- TMS·OTf-Catalyzed α-bromination of carbonyl compounds by N-bromosuccinimide
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Various carbonyl compounds undergo α-bromination reaction under a mild and practical condition utilizing N-bromosuccinimide (NBS), catalyzed by trimethylsilyl trifluoromethanesulfonate (TMS·OTf). This method is also effective for the side-chain bromination of heteroaromatic carbonyl compounds without the ring brominations.
- Guha, Samar Kumar,Wu, Bo,Kim, Beom Soo,Baik, Woonphil,Koo, Sangho
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p. 291 - 293
(2007/10/03)
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- Synthesis and evaluation of heteroaryl-substituted dihydronaphthalenes and indenes: Potent and selective inhibitors of aldosterone synthase (CYP11B2) for the treatment of congestive heart failure and myocardial fibrosis
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In this study, the synthesis and biological evaluation of heteroaryl-substituted dihydronaphthalenes and indenes (1-16) is described. The compounds were tested for activity by use of human CYP11B2 expressed in fission yeast and V79 MZh cells and for selectivity by use of human CYP11B1, CYP17, and CYP19. The most active inhibitor was the 6-methoxydihydronaphthalene 4 (IC 50 = 2 nM), showing a Ki value of 1.3 nM and a competitive type of inhibition. The 5-methoxyindene 3 was found to be the most selective CYP11B2 inhibitor (IC50 = 4 nM; CYP11B1 IC50 = 5684 nM), which also showed only marginal inhibition of human CYP3A4 and CYP2D6. Docking and molecular dynamics studies using our homology-modeled CYP11B2 structure were performed to understand some structure-activity relationships. Caco-2 cell experiments revealed highly cell-permeable compounds, and metabolic studies with 4 using rat liver microsomes showed sufficient stability.
- Voets, Marieke,Antes, Iris,Scherer, Christiane,Müller-Vieira, Ursula,Biemel, Klaus,Marchais-Oberwinkler, Sandrine,Hartmann, Rolf W.
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p. 2222 - 2231
(2007/10/03)
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