- A green catalytic method for selective synthesis of iodophenols via aerobic oxyiodination under organic solvent-free conditions
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A highly efficient catalytic method for aerobic oxyiodination of various phenols catalysed by copper(II) nitrate was achieved under mild conditions using I2as an iodinating reagent, molecular oxygen as an oxidant, and water as a solvent. The catalyst shows not only high activity for phenols with either electron-donating or electron-withdrawing groups, but also a remarkable selectivity for the formation of para-iodo substituted phenols. This study offers a green method for iodination of aromatic phenols with high atom economy.
- Xin, Hongchuan,Hu, Liangning,Yu, Jianqiang,Sun, Wenshou,An, Zengjian
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- New Acyloxymethyl Ketones: Useful Probes for Cysteine Protease Profiling
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Peptidyl-acyloxymethyl ketones (AOMKs) belong to a class of selective, irreversible inhibitors (activity-based probes) widely used as chemical tools of investigating proteins, for example, in activity-based protein profiling. The synthesis of the AOMKs has always been challenging and current methodologies involve both solution and solid-phase synthesis. Herein, the synthesis of a new scaffold useful for the preparation of peptidyl-AOMKs is reported and it is demonstrated that the new synthetic probes bearing a 4-functionalized 2,6-dimethylbenzoate efficiently inhibit cysteine proteases like cathepsin B.
- Coman, Anca G.,Paraschivescu, Codruta C.,Hadade, Niculina D.,Juncu, Andrei,Vlaicu, Ovidiu,Popescu, Costin-Ioan,Matache, Mihaela
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p. 3917 - 3923
(2016/11/11)
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- Efficient and Practical Oxidative Bromination and Iodination of Arenes and Heteroarenes with DMSO and Hydrogen Halide: A Mild Protocol for Late-Stage Functionalization
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An efficient and practical system for inexpensive bromination and iodination of arenes as well as heteroarenes by using readily available dimethyl sulfoxide (DMSO) and HX (X = Br, I) reagents is reported. This mild oxidative system demonstrates a versatile protocol for the synthesis of aryl halides. HX (X = Br, I) are employed as halogenating reagents when combined with DMSO which participates in the present chemistry as a mild and inexpensive oxidant. This oxidative system is amenable to late-stage bromination of natural products. The kilogram-scale experiment (>95% yield) shows great potential for industrial application.
- Song, Song,Sun, Xiang,Li, Xinwei,Yuan, Yizhi,Jiao, Ning
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supporting information
p. 2886 - 2889
(2015/06/30)
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- Gas-Chromatographic identifi cation of products formed in iodination of methyl phenols by retention indices
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Iodination reaction followed by conversion of iodine-substituted methylphenols to the corresponding trifl uoroacetates was suggested for improving the sensitivity of the gas-chromatographic determination of phenol and its methyl-substituted derivatives (al isomers of mono- and diethylphenols, 2,3,5-, 2,3,6-, and 3,4,5-trimethylphenols) in aqueous media. Acylation products of iodo methylphenols (104 compounds) were identifi ed by linear-logarithmic retention indices on a standard nonpolar polydimethylsiloxane stationary phase, and the pattern of their variation with the number and nature of substituents were characterized. A procedure for identifi cation of methyl-substituted phenols in water in their gas-chromatographic determination with an electron-capture detector was developed. Pleiades Publishing, Ltd., 2012.
- Gruzdev,Kuzivanov,Zenkevich,Kondratenok
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p. 1355 - 1365
(2013/01/15)
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- Selectivity enhancement of aromatic halogenation reactions at the micellar interface: Effect of highly ionic media
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Halogenation (iodination and bromination) of various aromatic compounds has been studied in micellar media in order to observe the effect on regioselectivity and conversion of the reaction. The addition of surfactant causes a change in the chemical shifts of the aromatic proton resonance of phenol which proves the orientation of the aromatic compound on the micellar surface. However, increase in ionic strength of the reaction media affects the selectivity of reaction by disturbing this spatial orientation of the aromatic compound in the micelle. Selectivity towards particular isomers is dependent on the concentration of the surfactant. In bromination of chlorobenzene (deactivated aromatic compound) enhancement in selectivity and conversion towards the para isomer has been observed.
- Samant, Bhupesh S.,Bhagwat, Sunil S.
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scheme or table
p. 1039 - 1044
(2012/10/18)
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- Development of an asymmetric hydrogenation route to (S)- N -Boc-2,6-dimethyltyrosine
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An improved, simpler and potentially more economical route to (S)-N-Boc-2,6-dimethyltyrosine 1, based on a previously published route, is presented. Key modifications were to prepare the dehydroaminoacid hydrogenation substrate 6 in a one-pot process directly from serine methyl ester and 4-iodo-3,5-dimethylphenyl acetate 4 and to identify a significantly more active asymmetric hydrogenation catalyst that allowed a 5-fold reduction in catalyst loading.
- Praquin, Celine F. B.,De Koning, Pieter D.,Peach, Philip J.,Howard, Roger M.,Spencer, Sarah L.
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experimental part
p. 1124 - 1129
(2012/01/06)
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- Mild and efficient oxy-iodination of alkynes and phenols with potassium iodide and tert-butyl hydroperoxide
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An efficient synthesis of 1-iodoalkynes and iodophenols was easily achieved by employing simple KI and TBHP. The reaction does not involve the use of a metal and base combination. A variety of substituted alkynes and phenols were prepared with good to excellent yield.
- Rajender Reddy,Venkateshwar,Uma Maheswari,Santhosh Kumar
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supporting information; experimental part
p. 2170 - 2173
(2010/06/14)
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- Modified o-methyl-substituted IBX: room temperature oxidation of alcohols and sulfides in common organic solvents
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o-Methyl-substituted Me-IBX is the first modified analog of IBX that oxidizes alcohols in common organic solvents at room temperature, due to a composite of two factors, that is, low solubility and hypervalent twisting-promoted rate enhancement. Furthermore, the reagent is efficient for selective oxidation of sulfides to sulfoxides, a transformation that otherwise occurs only sluggishly with standard IBX. The facile synthetic accessibility and its mild as well as non-hazardous nature render Me-IBX a stable equivalent of Dess-Martin periodinane reagent in organic oxidations.
- Moorthy, Jarugu Narasimha,Singhal, Nidhi,Senapati, Kalyan
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- Iodination of aromatic compounds using potassium iodide and hydrogen peroxide
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A simple, efficient, regioselective, and ecofriendly method for oxyiodination of aromatic compounds is presented. In this method, the electrophilic substitutions of iodine generated in situ from KI as an iodine source and hydrogen peroxide as an oxygen source have been employed without any catalyst/mineral acid for the first time. Copyright Taylor & Francis Group, LLC.
- Reddy, K. Suresh Kumar,Narender,Rohitha,Kulkarni
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experimental part
p. 3894 - 3902
(2009/04/04)
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- Eco-friendly oxyiodination of aromatic compounds using ammonium iodide and hydrogen peroxide
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A new eco-friendly procedure for the oxyiodination of aromatic compounds with NH4I as an iodine source and H2O2 as an oxidant without any catalyst is presented.
- Narender,Reddy, K. Suresh Kumar,Mohan, K.V.V. Krishna,Kulkarni
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p. 6124 - 6128
(2008/03/12)
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- Highly selective iodination of phenols using potassium iodide and benzyltriphenylphosphonium peroxymonosulfate
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An easy and selective method for monoiodination of phenols using potassium iodide in the presence of benzyltriphenylphosphonium peroxymonosulfate is presented. The reactions have been carried out in acetonitrile to afford the corresponding iodophenols in
- Hajipour, Abdol Reza,Adibi, Hadi
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p. 294 - 295
(2007/10/03)
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- Stereospecific synthesis of (2S)-2-methyl-3-(2′,6′-dimethyl-4′-hydroxyphenyl)-propionic acid (Mdp) and its incorporation into an opioid peptide
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To examine the effect of replacing the N-terminal amino group in opioid peptides with a methyl group on biological activity, a stereospecific synthesis of the tyrosine analogue (2S)-2-methyl-3-(2′,6′-dimethyl-4′-hydroxyphenyl)-propionic acid (Mdp) was performed. The enkephalin analogue (2S)-Mdp-D-Ala-Gly-Phe-Leu-NH2 turned out to be a quite potent δ opioid antagonist and a somewhat less potent μ antagonist, indicating that a positively charged N-terminal amino group is not a conditio sine qua non for the binding of opioid peptides to δ and μ receptors but may be required for signal transduction.
- Lu, Yixin,Weltrowska, Grazyna,Lemieux, Carole,Chung, Nga N.,Schiller, Peter W.
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p. 323 - 325
(2007/10/03)
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- Stereospecific syntheses of 2-alkyl and 2-phenyl substituted 3-(2,6-dimethyl-4-hydroxyphenyl)propanoic acids
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Stereospecific syntheses of 2-methyl-, 2-ethyl-, 2-cyclohexyland 2-phenyl- substituted 3-(2,6-dimethyl-4-hydroxyphenyl)propanoic acids were developed. The key steps for the formation of the stereogenic centers involved the utilization of Evans' 4-benzyl-2-oxazolidinone chiral auxiliary. These compounds were designed to replace the N-terminal tyrosine residue in opioid peptides.
- Lu,Schiller
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p. 1639 - 1644
(2007/10/03)
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- Novel ligands lacking a positive charge for the δ- and μ-opioid receptors
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Recently we reported using minilibraries to replace Lys [somatostatin (SRIF) numbering] of the potent somatostatin agonist L-363,301 (c[-Pro-Phe-D- Trp-Lys-Thr-Phe-]) to generate the potent neurokinin receptor (NK-1) antagonist c[-Pro-Phe-D-Trp-p-F-Phe-Thr-Phe-]. This novel cyclic hexapeptide did not bind the SRIF receptor. Thus, a single mutation converted L-363,-301, a SRIF agonist with potency ca. 2-8 times the potency of SRIF in laboratory animals, into a selective NK-1 receptor antagonist with an IC50 of 2 nM in vitro. During the screening of the same libraries for ligands of the δ- opioid receptor, we identified four compounds (1-4) which represent a new class of δ-opioid antagonists, some of which were also NK-1 receptor antagonists. The most potent δ-opioid antagonist, c[-Pro-1-Nal-D-Trp-Tyr- Thr-Phe-] (2), showed a K(e) value of 128 nM in the mouse vas deferens assay and a δ-receptor binding affinity constant of 152 nM in the rat brain membrane binding assay. These results are of interest because they represent a novel class of δ-opioid antagonists and, like two previously reported δ- opioid antagonists, they lack a positive charge. To examine further the requirement for a positive charge in the δ-opioid ligands, we prepared two analogues of the β-casomorphin-derived mixed μ-agonist/δ-antagonist, H- Dmt-c[-D-Orn-2-Nal-D-Pro-Gly-] (7), in which we eliminated the positive charge either through formylation of the primary amino group (5) or by the deletion of this N-terminal amino group (6). These latter compounds proved to be δ-opioid antagonists with K(e) values in the 16-120 nM range, as well as fairly potent μ-opioid antagonists (K(e) ? 200 nM). These six compounds provide the most convincing evidence to date that there is no requirement for a positive charge in μ- and δ-opioid receptor antagonists. In addition, cyclic, hexapeptide 4 lacks a phenolic hydroxyl group. Taken together, these data suggest that the prevailing assumptions about δ- and μ-opioid receptor binding need revision and that the receptors for these opioid ligands have much in common with the NK-1 and somatostatin receptors.
- Schiller, Peter W.,Berezowska, Irena,Nguyen, Thi M.-D.,Schmidt, Ralf,Lemieux, Carole,Chung, Nga N.,Falcone-Hindley, Margaret L.,Yao, Wenqing,Liu, Josephine,Iwama, Seiji,Smith III, Amos B.,Hirschmann, Ralph F.
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p. 551 - 559
(2007/10/03)
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- Process for producing 2,6-disubstituted tyrosine
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A process for making 2,6-disubstituted tyrosine by the noble metal coupling of a disubstituted aromatic halide or diazonium salt with an amino-protected 2-aminoacrylic acid to form a (Z)-β-(disubstituted phenyl)-α-acylaminoacrylate, and asymmetrically hydrogenating the acrylate to produce the 2,6-disubstituted tyrosine.
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- Iodination of Phenols by Use of Benzyltrimethylammonium Dichloroiodate(1-)
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The reaction of phenols with benzyltrimethylammonium dichloroiodate(1-) in dichloromethane-methanol in the presence of CaCO3 or NaHCO3 for several hours at room temperature gave iodophenols in good yields.
- Kajigaeshi, Shoji,Kakinami, Takaaki,Yamasaki, Hiromichi,Fujisaki, Shizuo,Kondo, Manabu,Okamoto, Tsuyoshi
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p. 2109 - 2112
(2007/10/02)
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