- Mono-selective β-C-H arylation of: N -methylated amino acids and peptides promoted by the 2-(methylthio)aniline directing group
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2-(Methylthio)aniline (MTA) directed C(sp3)-H functionalisations are efficient and straightforward protocols for the selective β-modification of N-methylated amino acids. The decreased reactivity of MTA in comparison with the 8-aminoquinoline (AQ) directing group allows for selective monoarylations in high yields without the formation of side products. The protocol is also suitable for the introduction of highly functionalised side chains onto the C-terminal alanines of dipeptides. The MTA directing group can easily be removed, providing free carboxylic acids as valuable building blocks.
- Kinsinger, Thorsten,Kazmaier, Uli
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- Selectivity in the Iodination of Phenol in the Presence of β-Cyclodextrin
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The ratio of products formed in the iodination of phenol and o-chlorophenol with I2/I- in water solution depends on the pH and buffer concentration.At high pH and high buffer concentration the para/ortho ratio increases.This ratio also increases in the presence of β-cyclodextrin (CD).The kinetics of the iodination reaction was measured for phenol, o-iodophenol, o-chlorophenol, and p-iodophenol, and in all cases the observed rate decreases with the addition of CD.The decrease in the overall rate is due to consumption of the active iodinating species through complexation of I2, I-, and I3- with CD.The iodination occurs in the bound substrates as well as in the free substrates.The equilibrium constants for the association of the phenols with CD were determined, and it is possible to conclude that the reaction of the bound substrates is faster than that of the free substrates not only for the para position but also for the ortho position. The catalysis is attributed mainly to a microsolvent effect which in the case of the ortho position is counterbalanced by a steric effect.
- Veglia, Alicia V.,Rossi, Rita H. de
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- A quantitative structure-reactivity assessment of phenols by investigation of rapid iodination kinetics using hydrodynamic voltammetry: Applicability of the Hammett equation in aqueous medium
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Halogenations of aromatic substrates in aqueous medium are essentially electrophilic substitutions proceeding at rates concomitant with the nature of the substrates and substituent motifs. Kinetics as an investigatory tool for the quantitative assessment of the structure-reactivity correlation in these reactions for a diverse range of substrates has rarely been reported, presumably due to the rapidity of these reactions in aqueous medium. We have used hydrodynamic voltammetry to investigate the rapid kinetics of uncatalyzed iodination of phenol and eight substituted phenols by iodine monochloride at constant pH in aqueous medium. The Arrhenius plots for these reactions yield comprehensive kinetic and thermodynamic data. The quantitative structure-reactivity correlation stemming from the regio- and stereospecificity of the substituent motifs on the substrates has been examined through the Hammett plot, which shows a negative slope of 1.87. The magnitudes of the rate constants, energies of activation, frequency factors, and entropy change obtained for the nine fast reactions reported, reflect the relative ease of the reaction dynamics in quantitative terms thereby ascertaining the relative reactivities of the phenols studied herein.
- Borkar, Vitthal T.,Bonde, Shantaram L.,Dangat, Vijay T.
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- Ammonium Salt-Catalyzed Highly Practical Ortho-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
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An ortho-selective ammonium chloride salt-catalyzed direct C-H monohalogenation of phenols and 1,1′-bi-2-naphthol (BINOL) with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) as the chlorinating agent has been developed. The catalyst loading was low (down to 0.01 mol %) and the reaction conditions were very mild. A wide range of substrates including BINOLs were compatible with this catalytic protocol. Chlorinated BINOLs are useful synthons for the synthesis of a wide range of unsymmetrical 3-aryl BINOLs that are not easily accessible. In addition, the same catalytic system can facilitate the ortho-selective selenylation of phenols.
- Xiong, Xiaodong,Yeung, Ying-Yeung
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p. 4033 - 4043
(2018/05/22)
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- C-H Functionalization of N-Methylated Amino Acids and Peptides as Tool in Natural Product Synthesis: Synthesis of Abyssenine A and Mucronine e
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N-Methylated amino acids and peptides with an 8-aminoquinoline (AQ) directing group can be subjected to stereoselective Pd-catalyzed β-functionalizations. The best results are obtained with aryl iodides, but alkyl and alkenyl side chains can also be introduced. The AQ protecting group can easily be removed, providing the free carboxylic acid, which can be used directly in peptide couplings. This protocol was used successfully as a key step in the synthesis of the cyclopeptide alkaloids abyssenine A and mucronine E.
- Kinsinger, Thorsten,Kazmaier, Uli
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supporting information
p. 7726 - 7730
(2018/12/11)
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- 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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- Isoquinolinium Dichromate and Chlorochromate as Efficient Catalysts for Oxidative Halogenation of Aromatic Compounds under Acid-Free Conditions
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Isoquinolinium dichromate and isoquinolinium chlorochromate were found as efficient catalysts to trigger oxidative bromination and iodination of aromatic hydrocarbons with KBr/KI and KHSO4 under acid-free conditions. Reaction times reduced highly significantly under sonication, followed by corresponding mono bromo derivatives in very good yield with high regioselectivity.
- Rao, A. Sambashiva,Rajanna,Reddy, K. Rajendar,Kulkarni, Subhash
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p. 832 - 837
(2016/02/12)
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- Using Anilines as Masked Cross-Coupling Partners: Design of a Telescoped Three-Step Flow Diazotization, Iododediazotization, Cross-Coupling Process
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The conversion of commercially available anilines into biaryl and biarylacetylene products was realized by using a telescoped, three-reactor flow diazotization/iododediazotization/cross-coupling process. The segmented flow stream created by off-gassing during the Sandmeyer sequence was restored to a continuous column of reaction solution by using a specially designed continuous-flow unit controlled by custom software created in-house. The resultant aryl iodide was then combined with a stream of cross-coupling solution that fed into the final reactor. The system proved versatile as modifications to the diazotization/iododediazotization sequence could be made rapidly to account for any substrate specificity (e.g., solubility problems), leading to a wide substrate scope of Suzuki–Miyaura and Sonogashira cross-coupled products.
- Teci, Matthieu,Tilley, Michael,McGuire, Michael A.,Organ, Michael G.
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supporting information
p. 17407 - 17415
(2016/11/23)
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- Copper-catalyzed domino route to natural nostoclides and analogues: A total synthesis of nostoclides i and II
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An original and convenient domino route to natural nostoclides I and II has been developed using a two-step sequence consisting of a copper-cat-alyzed tandem reaction associated with Suzuki cross-coupling. The methodology employed for this total synthesis appeared to be an interesting and suffi-ciently flexible tool to allow the synthesis of numer-ous analogues of these nostoclides.
- Ngi, Samuel Inack,Petrignet, Julien,Duwald, Romain,El Hilali, El Mostafa,Abarbri, Mohamed,Duchêne, Alain,Thibonnet, Jér?me
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p. 2936 - 2941
(2014/03/21)
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- Regioselective iodination of aromatic compounds with potassium iodide in the presence of benzyltriphenylphosphonium perchlorate
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A simple and efficient method for the selective iodination of various aromatic compounds by using potassium iodide in the presence of benzyltriphenylphosphonium perchlorate, is reported. This method provides several advantages such as good selectivity between ortho and para positions of aromatic compounds and high yields of the products.
- Albadi, Jalal,Abedini, Masoumeh,Iravani, Nasir
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experimental part
p. 261 - 264
(2012/05/07)
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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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- Environmental friendly method for the iodination of moderately active arenes
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An effective and environmental friendly method for the iodination of various moderately active methoxy arenes, phenols and anilines using hydrogen peroxide and acidified sodium periodate in aqueous ethanol medium is reported. The extent of iodination is e
- Sathiyapriya
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experimental part
p. 41 - 43
(2011/11/13)
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- Green and efficient method for the iodination of phenols in water
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In this article, green conversion of phenols to the corresponding iodide derivatives is reported. The reactions were conducted in water, using potassium iodide as the source of iodine and potassium ferrate as the oxidizing agent. The selected phenols were successfully iodinated in good to excellent yields in mild and non-toxic reaction conditions. Copyright Taylor & Francis Group, LLC.
- Tajik, Hassan,Dadras, Akbar,Hosseini, Abolfazl
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experimental part
p. 258 - 261
(2011/06/26)
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- Selective iodination of some phenols, anilines and methoxyarenes by molecular iodine in the presence of 1-butyl-3-methylimidazolium hydrogen sulphate
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A simple, mild and regioselective method for the iodination of some phenols, anilines and methoxyarenes by using molecular iodine in presence of 1-butyl-3-methylimidazolium hydrogen sulphate ([bmim]-HSO4) in acetonitrile as solvent is reported. One-pot synthesis, mild reaction conditions, short reaction times and excellent yields of the products are noteworthy.
- Tajik, Hassan,Parsa, Fatemeh
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experimental part
p. 465 - 466
(2011/10/19)
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- Non-nucleoside inhibitors of human adenosine kinase: Synthesis, molecular modeling, and biological studies
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Adenosine kinase (AK) catalyzes the phosphorylation of adenosine (Ado) to AMP by means of a kinetic mechanism in which the two substrates Ado and ATP bind the enzyme in a binary and/or ternary complex, with distinct protein conformations. Most of the desc
- Butini, Stefania,Gemma, Sandra,Brindisi, Margherita,Borrelli, Giuseppe,Lossani, Andrea,Ponte, Anna Maria,Torti, Andrea,Maga, Giovanni,Marinelli, Luciana,La Pietra, Valeria,Fiorini, Isabella,Lamponi, Stefania,Campiani, Giuseppe,Zisterer, Daniela M.,Nathwani, Seema-Maria,Sartini, Stefania,La Motta, Concettina,Da Settimo, Federico,Novellino, Ettore,Focher, Federico
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experimental part
p. 1401 - 1420
(2011/04/24)
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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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- FLUORINATION OF ORGANIC COMPOUNDS
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Methods for fluorinating organic compounds are described herein.
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Page/Page column 77; 78
(2010/07/10)
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- Regioselective iodination of phenol and analogues using N-iodosuccinimide and p-toluenesulfonic acid
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Mild and highly regioselective monoiodination of phenol and analogues is achieved in high to excellent yields at room temperature with a combination of stoichiometric p-toluenesulfonic acid and N-iodosuccinimide.
- Bovonsombat, Pakorn,Leykajarakul, Juthamard,Khan, Chiraphorn,Pla-on, Kawin,Krause, Michael M.,Khanthapura, Pratheep,Ali, Rameez,Doowa, Niran
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scheme or table
p. 2664 - 2667
(2009/08/09)
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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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- Preparation of a psammaplysene-based library
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(Chemical Equation Presented) A 28-member focused library, based on the pseudosymmetric template of the marine alkaloids psammaplysenes, was prepared from combinations of components that were, in turn, derived from 4-iodophenol.
- Georgiades, Savvas N.,Clardy, Jon
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p. 4251 - 4254
(2007/10/03)
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- Simple and regioselective oxyiodination of aromatic compounds with ammonium iodide and Oxone
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Oxyiodination of aromatic compounds using NH4I and Oxone gives high yields and selectivity. A simple method for the iodination of aromatic compounds using NH4I as the iodine source and Oxone as the oxidant is described.
- Krishna Mohan,Narender,Kulkarni
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p. 8015 - 8018
(2007/10/03)
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- Synthesis of alkenyldiarylmethane (ADAM) non-nucleoside HIV-1 reverse transcriptase inhibitors with non-Identical aromatic rings
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The existing methods for the synthesis of alkenyldiarylmethane (ADAM) non-nucleoside reverse transcriptase inhibitors proceed from symmetrical benzophenones and therefore result in products with identical aromatic rings. New methods have therefore been de
- Xu, Guozhang,Hartman, Tracy L.,Wargo, Heather,Turpin, Jim A.,Buckheit Jr., Robert W.,Cushman, Mark
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p. 283 - 290
(2007/10/03)
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- An Efficient and Selective Method for the Preparation of Iodophenols
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Direct iodination of a wide range of phenols may be achieved with unprecedented selectivity in aqueous alcohol solvents by the action of a reagent preparated in situ from sodium hypochlorite and sodium iodide.Para-substituted phenols (or ortho-substituted, when the para-position is already occupied) are obtained in fair to excellent yields by simple isolation techniques.The extent of iodination is easily controlled by stoichiometry.The technique is also useful with some anilines.
- Edgar, Kevin J.,Falling, Stephen N.
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p. 5287 - 5291
(2007/10/02)
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