- Total Synthesis of Caesalpinnone A
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Total synthesis of caesalpinnone A was achieved in 12 steps starting from resorcinol. Key features of the synthesis include BINOL-phosphoric acid catalyzed [4 + 2] cycloaddition, trans-selective nucleophilic substitution, deallylation/oxa-Michael addition cascade, and late-stage photo-Fries rearrangement.
- Liu, Zhigang,Meng, Yifei,Yuan, Pengrui,Wang, Zhengshen,Gao, Jin-Ming,Zheng, Huaiji
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Read Online
- Electrochemical synthesis of quinones and other derivatives in biphasic medium
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Electrochemical synthesis of quinones has been attempted from phenols, 1,4-dihydroxybenzenes, 1,4-dihydroxynaphthalenes and related compounds using biphasic media. Excellent yields of quinones (98%) or brominated diols have been achieved with good current efficiency. Reuse of the electrolyte without any modification and quantitative conversion of substrate with theoretical amount of current are the advantages of this method.
- Shanmugam,Kulangiappar,Ramaprakash,Vasudevan,Senthil Kumar,Velayutham,Raju
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p. 2294 - 2297
(2017/05/19)
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- Rapid and total bromination of aromatic compounds using TsNBr2 without any catalyst
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N,N-Dibromo-p-toluenesulfonamide (TsNBr2) has been found to be a new reagent for bromination of aromatic compounds. The reaction is extremely fast and goes into completion instantaneously at ambient temperature to produce exclusively the corresponding polybrominated product. This procedure is applicable to various phenols, anisole, and anilines to give corresponding polybrominated compound as a single product in excellent yield.
- Saikia, Indranirekha,Chakraborty, Pranita,Sarma, Manas Jyoti,Goswami, Mridusmita,Phukan, Prodeep
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p. 211 - 217
(2015/10/29)
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- Copper(II)-catalyzed aromatization followed by bromination of cyclohexenones leading to phenols and bromophenols
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Conversion of substituted cyclohexenones into the corresponding phenols can be achieved using copper acetate as the catalyst in the presence of LiBr and CF3COOH under oxygen. With the use of excess LiBr, electrophilic aromatic bromination afforded the corresponding bromophenol under similar catalytic conditions. Copyright
- Tong, Hung-Chun,Reddy, K. Rajender,Liu, Shiuh-Tzung
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p. 3256 - 3261
(2014/06/09)
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- Solvent-free bromination reactions with sodium bromide and oxone promoted by mechanical milling
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New solvent-free brominations of 1,3-dicarbonyl compounds, phenols, various alkenes including chalcones, azachalcones, 4-phenylbut-3-en-2-one, methyl cinnamate, styrene and 1,3-cyclohexadiene were efficiently achieved by employing sodium bromide and oxone under mechanical milling conditions. The brominated products were obtained in good to excellent yields.
- Wang, Guan-Wu,Gao, Jie
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experimental part
p. 1125 - 1131
(2012/06/04)
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- Urolithin as a Converging Scaffold Linking Ellagic acid and Coumarin Analogues: Design of Potent Protein Kinase CK2 Inhibitors
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Casein kinase2 (CK2) is a ubiquitous, essential, and highly pleiotropic protein kinase; its abnormally high constitutive activity is suspected to underlie its pathogenic potential in neoplasia and other relevant diseases. Previously, using different in silico screening approaches, two potent and selective CK2 inhibitors were identified by our group: ellagic acid, a naturally occurring tannic acid derivative (Ki=20nM) and 3,8-dibromo-7-hydroxy-4-methylchromen-2-one (DBC, Ki=60nM). Comparing the crystallographic binding modes of both ellagic acid and DBC, an X-ray structure-driven merging approach was taken to design novel CK2 inhibitors with improved target affinity. A urolithin moiety is proposed as a possible bridging scaffold between the two known CK2 inhibitors, ellagic acid and DBC. Optimization of urolithinA as the bridging moiety led to the identification of 4-bromo-3,8-dihydroxy-benzo[c]chromen-6-one as a novel, potent and selective CK2 inhibitor, which shows a Ki value of 7nM against the protein kinase, representing a significant improvement in affinity for the target compared with the two parent fragments. Two become one: Comparing the crystallographic binding modes of ellagic acid (red) and 3,8-dibromo-7-hydroxy-4-methylchromen-2-one (DBC; blue), an X-ray structure-driven merging approach to the design of novel casein kinase2 (CK2) inhibitors was taken. Using this strategy, a potent and selective urolithin derivative, 4-bromo-3,8-dihydroxy-benzo[c]chromen-6-one was identified, which exhibits a Ki value of 7nM against CK2.
- Cozza, Giorgio,Gianoncelli, Alessandra,Bonvini, Paolo,Zorzi, Elisa,Pasquale, Riccardo,Rosolen, Angelo,Pinna, Lorenzo A.,Meggio, Flavio,Zagotto, Giuseppe,Moro, Stefano
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experimental part
p. 2273 - 2286
(2012/04/11)
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- Towards allosteric receptors - Synthesis of Resorcinarene-Functionalized 2,2′-Bipyridines and their metal complexes
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Based on a first: example of an allosteric hemicarcerand (1) we prepared four new 2,2′bipyridines that carry resorcinarene moieties in a highly convergent manner. Upon coordination to suitable transition metal ions or their complexes these compounds undergo conformational changes in a way that: they switch between "open" and. "closed" forms (2, 3, and 4) or vice versa (5), thus, bringing together or separating the two functional, moieties on the central, bipyridine, Among the transition metal complexes that act: as effectors for the conformational switching, [Re(CO)5Cl] and monomeric copper(I) complexes of sterically hindered 2,9-arylated 1,10-phenanthrolines proved, to be very effective.
- Staats, Holger,Eggers, Friederike,Hass, Oliver,Fahrenkrug, Frank,Matthey, Jens,Luening, Ulrich,Luetzen, Arne
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experimental part
p. 4777 - 4792
(2009/12/25)
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- 1-Benzyl-4-aza-1-azoniabicyclo[2.2.2]octane tribromide as a regenerable and useful reagent for bromination of phenols under mild conditions
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1-Benzyl-4-aza-1-azoniabicyclo[2.2.2]octane tribromide has been examined over several phenolic compounds under mild conditions. The reaction gives brominated phenols in good to excellent yields. Straightforward work-up of the reaction yields pure products in several cases.
- Hajipour, Abdol R.,Pourmousavi, Seied A.,Ruoho, Arnold E.
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p. 796 - 800
(2007/10/03)
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- A controlled and selective bromination of phenols by benzyltriphenylphosphonium tribromide
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Reactions of phenols with benzyltriphenylphosphonium tribromide in dichloromethane-methanol mixture (2:1) gave mono, di and tri brominated phenols at room temperature with high selectivity and good yields.
- Hajipour, Abdol Reza,Mallakpour, Shadpour E.,Imanieh, Hossein,Pourmousavi, Seied A.
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p. 272 - 275
(2007/10/03)
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- A facile route to Aryl-substituted 1,10-phenanthrolines by means of Suzuki coupling reactions between substituted areneboronic acids and halogeno-1,10-phenanthrolines
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Twelve new mono- or diaryl-substituted 1,10-phenanthrolines (17 and 18) have been synthesized. The key step is a Suzuki coupling reaction between the substituted areneboronic acids 6, 11, and 15 and the mono- and dihalo-1,10-phenanthrolines 16. The syntheses of bis-ortho-substituted boronic acids 6, 11, and 15 from substituted arenes 5 or substituted bromoarenes 10 and 14 by lithiation and subsequent treatment with trimethyl borate is described. Not only 2,9-diiodo- (16c) but also 2,9-dichloro-1,10-phenanthroline (16b) can be used with good yields (65-92%) in the described Suzuki coupling. For the syntheses of unsymmetrically substituted 1,10-phenanthrolines 18b, 18i, and 18j, the use of 2- chloro-9-iodo-1,10-phenanthroline is not necessary; two different bis-ortho-substituted arene rings can be introduced stepwise in 46 to 64% total yield. ( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
- Luening, Ulrich,Abbass, Michael,Fahrenkrug, Frank
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p. 3294 - 3303
(2007/10/03)
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- Halogenation Using Quaternary Ammonium Polyhalides. IV. Selective Bromination of Phenols by Use of Tetraalkylammonium Tribromides
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Reaction of phenols with calculated amounts of benzyltrimethylammonium tribromide or tetrabutylammonium tribromide in dichloromethane-methanol for 0.5-1 h under mild conditions gave, selectively, the objective mono-, di-, or tribromophenols in good yields.
- Kajigaeshi, Shoji,Kakinami, Takaaki,Okamoto, Tsuyoshi,Nakamura, Hiroko,Fujikawa, Masahiro
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p. 4187 - 4189
(2007/10/02)
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