- Activator free, expeditious and eco-friendly chlorination of activated arenes by N-chloro-N-(phenylsulfonyl)benzene sulfonamide (NCBSI)
-
N-Chloro-N-(phenylsulfonyl)benzene sulfonamide (NCBSI) has been explored for the first time as a chlorinating reagent for direct chlorination of various activated arenes and heterocycles without any activator. A comparative in-silico study was performed to determine the electrophilic character for NCBSI and commercially available N-chloro reagents to reveal the reactivity on a theoretical viewpoint. The reagent was prepared by an improved method avoiding the use of hazardous t-butyl hypochlorite. This reagent was proved to be very reactive compared to other N-chloro reagents. The precursor of the reagent N-(phenylsulfonyl)benzene sulfonamide was recovered from aqueous spent, which can be recycled to synthesize NCBSI. The eco-friendly protocol was equally applicable for the synthesis of industrially important chloroxylenol as an antibacterial agent.
- Misal, Balu,Palav, Amey,Ganwir, Prerna,Chaturbhuj, Ganesh
-
supporting information
(2021/01/04)
-
- Sulfoxide-Promoted Chlorination of Indoles and Electron-Rich Arenes with Chlorine as Nucleophile
-
An efficient chlorination of indoles and electron-rich arenes with chlorine anion as nucleophile is described. With the use of ethyl phenyl sulfoxide as the promoter, the reaction went smoothly under metal-free and mild conditions. Various indoles and electron-rich arenes are converted into the corresponding chlorinated compounds in moderate to excellent yields. A plausible interrupted Pummerer reaction mechanism was proposed without the oxidation of chloride anion. In addition, the byproduct thioether could be easily converted to the starting material sulfoxide just by a simple oxidation reaction. (Figure presented.).
- Ji, Yuan-Zhao,Li, Hui-Jing,Wang, Yi-Ruo,Wu, Yan-Chao,Zhang, Zheng-Yan
-
supporting information
(2020/02/05)
-
- Amplification of Trichloroisocyanuric Acid (TCCA) Reactivity for Chlorination of Arenes and Heteroarenes via Catalytic Organic Dye Activation
-
Heteroarenes and arenes that contain electron-withdrawing groups are chlorinated in good to excellent yields (scalable to gram scale) using trichloroisocyanuric acid (TCCA) and catalytic Brilliant Green (BG). Visible-light activation of BG serves to amplify the electrophilic nature of TCCA, providing a mild alternative approach to acid-promoted chlorination of deactivated (hetero)aromatic substrates. The utility of the TCCA/BG system is demonstrated through comparison to other chlorinating reagents and by the chlorination of pharmaceuticals including caffeine, lidocaine, and phenazone.
- Rogers, David A.,Bensalah, Adam T.,Espinosa, Alvaro Tomas,Hoerr, John L.,Refai, Fares H.,Pitzel, Amy K.,Alvarado, Juan J.,Lamar, Angus A.
-
supporting information
p. 4229 - 4233
(2019/06/17)
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- Iodine(III)-Mediated, Controlled Di- or Monoiodination of Phenols
-
An oxidative procedure for the electrophilic iodination of phenols was developed by using iodosylbenzene as a nontoxic iodine(III)-based oxidant and ammonium iodide as a cheap iodine atom source. A totally controlled monoiodination was achieved by buffering the reaction medium with K3PO4. This protocol proceeds with short reaction times, at mild temperatures, in an open flask, and generally with high yields. Gram-scale reactions, as well as the scope of this protocol, were explored with electron-rich and electron-poor phenols as well as heterocycles. Quantum chemistry calculations revealed PhII(OH)·NH3 to be the most plausible iodinating active species as a reactive "I+" synthon. In light of the relevance of the iodoarene moiety, we present herein a practical, efficient, and simple procedure with a broad functional group scope that allows access to the iodoarene core unit.
- Satkar, Yuvraj,Yera-Ledesma, Luisa F.,Mali, Narendra,Patil, Dipak,Segura-Quezada, Luis A.,Ramírez-Morales, Perla I.,Solorio-Alvarado, César R.,Navarro-Santos, Pedro
-
p. 4149 - 4164
(2019/04/30)
-
- Radical Truce-Smiles reactions on an isoxazole template: Scope and limitations
-
The use of TiCl3-HCl as promotor in the radical Truce-Smiles reactions of 2-(((3,5-dimethylisoxazol-4-yl)sulfonyl)oxy)benzenediazonium salts has been investigated in detail. During these reactions the desired Truce-Smiles rearrangement (via an ipso-substitution reaction) is accompanied by the formation of a number of by-products including dihydrobenzo[5,6][1,2]oxathiino[3,4-d]isoxazole 4,4-dioxides, dioxidobenzo[e][1,2]oxathiin-3-yl)ethan-1-ones, anilines and chloroaromatics. Replacing TiCl3-HCl by Cu(NO3)2-Cu2O as reductant in these reactions was found to afford broadly comparable product distributions. Competition and radical clock experiments also provide an indication of the relative susceptibility of the isoxazole nucleus towards attack by aryl radicals.
- Rashid, Srood O.,Almadhhi, Sultan S.,Berrisford, David J.,Raftery, James,Vitorica-Yrezabal, Inigo,Whitehead, George,Quayle, Peter
-
p. 2413 - 2430
(2019/03/23)
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- Ammonium Salt-Catalyzed Highly Practical Ortho-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
-
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
-
p. 4033 - 4043
(2018/05/22)
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- Regioselective Halogenation of Arenes and Heterocycles in Hexafluoroisopropanol
-
Regioselective halogenation of arenes and heterocycles with N-halosuccinimides in fluorinated alcohols is disclosed. Under mild condition reactions, a wide diversity of halogenated arenes are obtained in good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of one-pot sequential halogenation and halogenation-Suzuki cross-coupling reactions.
- Tang, Ren-Jin,Milcent, Thierry,Crousse, Benoit
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p. 930 - 938
(2018/01/28)
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- In Situ Formed IIII-Based Reagent for the Electrophilic ortho-Chlorination of Phenols and Phenol Ethers: The Use of PIFA-AlCl3 System
-
A new and in situ formed reagent generated by mixing PIFA {bis[(trifluoroacetoxy)iodobenzene]} and AlCl3 was introduced in the organic synthesis for the direct and highly regioselective ortho-chlorination of phenols and phenol ethers. An efficient electrophilic chlorination for these electron-rich arenes as well as the scope of the reaction are described herein. An easy, practical, and open-flask reaction allowed us to introduce a chlorine atom, which is a highly important functional group in organic synthesis. The reproducibility of our method has been demonstrated on gram-scale by carrying out the reaction in 6-bromo-2-naphthol. This halogenation reaction also proceeds in excellent conditions by first preparing the iodine(III)-based chlorinating reagent. Our new chlorinating reagent can be stored at least for two weeks at 4 °C without losing its reactivity.
- Nahide, Pradip D.,Ramadoss, Velayudham,Juárez-Ornelas, Kevin A.,Satkar, Yuvraj,Ortiz-Alvarado, Rafel,Cervera-Villanueva, Juan M. J.,Alonso-Castro, ángel J.,Zapata-Morales, Juan R.,Ramírez-Morales, Marco A.,Ruiz-Padilla, Alan J.,Deveze-álvarez, Martha A.,Solorio-Alvarado, César R.
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p. 485 - 493
(2018/02/09)
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- Iron(III)-Catalyzed Chlorination of Activated Arenes
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A general and regioselective method for the chlorination of activated arenes has been developed. The transformation uses iron(III) triflimide as a powerful Lewis acid for the activation of N-chlorosuccinimide and the subsequent chlorination of a wide range of anisole, aniline, acetanilide, and phenol derivatives. The reaction was utilized for the late-stage mono- and dichlorination of a range of target compounds such as the natural product nitrofungin, the antibacterial agent chloroxylenol, and the herbicide chloroxynil. The facile nature of this transformation was demonstrated with the development of one-pot, tandem, iron-catalyzed dihalogenation processes allowing highly regioselective formation of different carbon-halogen bonds. The synthetic utility of the resulting dihalogenated aryl compounds as building blocks was established with the synthesis of natural products and pharmaceutically relevant targets.
- Mostafa, Mohamed A. B.,Bowley, Rosalind M.,Racys, Daugirdas T.,Henry, Martyn C.,Sutherland, Andrew
-
p. 7529 - 7537
(2017/07/26)
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- Aromatic Monochlorination Photosensitized by DDQ with Hydrogen Chloride under Visible-Light Irradiation
-
Photochlorination of aromatic substrates by hydrogen chloride with 2,3-dichloro-5,6-cyano-p-benzoquinone (DDQ) occurs efficiently to produce the corresponding monochlorinated products selectively under visible-light irradiation. The yields for the chlorination of phenol were 70 % and 18 % for p- and o-chlorophenol, respectively, without formation of further chlorinated products. The photoinduced chlorination is initiated by electron transfer from Cl- to the triplet excited state of DDQ. The radical intermediates involved in the photochemical reaction have been detected by time-resolved transient absorption measurements.
- Ohkubo, Kei,Fujimoto, Atsushi,Fukuzumi, Shunichi
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p. 996 - 999
(2016/04/20)
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- A Doubly Biomimetic Synthetic Transformation: Catalytic Decarbonylation and Halogenation at Room Temperature by Vanadium Pentoxide
-
The halogenation of the C?H bond by metal-oxo-peroxo species and the decarbonylation of aldehydes by metal-peroxo species are performed routinely in biological systems. However, metal-mediated decarbonylative halogenation is unknown in nature. In this work, we have shown that widely available V2O5 and VO(acac)2 (acac=acetylacetonate) can catalyze decarbonylative halogenation through the generation of an intermediate vanadium-oxo-peroxo species, which was characterized by using 51 V NMR, UV/Vis, and resonance Raman spectroscopy. Further detection of formic acid from the reaction mixture confirmed the biomimetic aspects of decarbonylative halogenation. A detailed experimental and DFT study indicated a concerted mechanism for this decarbonylative halogenation performed under simple and mild reaction conditions.
- Rana, Sujoy,Pandey, Bhawana,Dey, Aniruddha,Haque, Rameezul,Rajaraman, Gopalan,Maiti, Debabrata
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p. 3367 - 3374
(2016/11/16)
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- CFBSA: a novel and practical chlorinating reagent
-
A structurally simple, highly reactive chlorinating reagent, N-chloro-N-fluorobenzenesulfonylamine (CFBSA), was conveniently prepared from inexpensive Chloramine B in high yield. A wide range of substrates were chlorinated with it to obtain products in good to high yields and appropriate selectivity.
- Lu, Zehai,Li, Qingwei,Tang, Minghua,Jiang, Panpan,Zheng, Hao,Yang, Xianjin
-
supporting information
p. 14852 - 14855
(2015/10/06)
-
- An approach to the synthesis of naphtho[b]furans from allyl bromonaphthyl ethers employing sequential photoinduced radical cyclization and dehydrohalogenation reactions
-
A simple method has been developed for the efficient synthesis of naphtho[b]furans from allyl bromonaphthyl ethers. The approach utilizes a novel photochemical process involving sequential radical cyclization and dehydrohalogenation. Because light is a readily available, environmentally friendly reagent that produces no by-products, the new process serves as a green synthetic method.
- Suzuki, Yusuke,Okita, Yoshiki,Morita, Toshio,Yoshimi, Yasuharu
-
supporting information
p. 3355 - 3357
(2014/06/09)
-
- Catalytic electrophilic halogenations and haloalkoxylations by non-heme iron halides
-
Synthetic non-heme iron halides promote sub-stoichiometric aliphatic halogenation reactions via a radical mechanism. Complementary to such activity, we have developed an electrophilic halogenation of arenes employing non-heme iron halides. A catalytic version of these reactions has also been developed using potassium halide as the source of halogen atom for arenes at room temperature. Efforts towards understanding the mechanism of these catalytic halogenation reactions led to the discovery of the haloalkoxylation of olefins by a non-heme iron complex. Implications of these findings with respect to natural transformations are also discussed.
- Rana, Sujoy,Bag, Sukdev,Patra, Tuhin,Maiti, Debabrata
-
supporting information
p. 2453 - 2458
(2014/09/30)
-
- Decarbonylative halogenation by a vanadium complex
-
Metal-catalyzed halogenation of the C-H bond and decarbonylation of aldehyde are conventionally done in nature. However, metal-mediated decarbonylative halogenation is unknown. We have developed the first metal-mediated decarbonylative halogenation reaction starting from the divanadium oxoperoxo complex K3V5+2(O 22-)4(O2-)2(μ-OH) (1). A concerted decarbonylative halogenation reaction was proposed based on experimental observations.
- Rana, Sujoy,Haque, Rameezul,Santosh, Ganji,Maiti, Debabrata
-
supporting information
p. 2927 - 2932
(2013/04/24)
-
- 2,4,6-Tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine as a new recyclable hypervalent iodine(III) reagent for chlorination and oxidation reactions
-
The synthesis of 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine, as a new recyclable nonpolymeric analogue of (dichloroiodo)benzene, is achieved in two steps using 2,4,6-trichloro-1,3,5-triazine and 4-iodophenol. The application of 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine for the chlorination reaction of various activated arenes, olefin, and 1,3-diketone is demonstrated. The reagent 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine can be applied also for the oxidative synthesis of 1,3,4-oxadiazoles and 1,2,4-thiadiazoles under mild conditions in excellent yields. The recyclability of the 2,4,6-tris[(4-dichloroiodo)phenoxy)]-1,3,5-triazine was possible owing to the facile recovery and reuse of the coproduced 2,4,6-tris(4-iodophenoxy)-1,3,5- triazine from the reaction mixture due to its practical insolubility in methanol. Georg Thieme Verlag Stuttgart, New York.
- Thorat, Prerana B.,Bhong, Bhagyashree Y.,Karade, Nandkishor Y.
-
supporting information
p. 2061 - 2066
(2013/10/21)
-
- Multicomponent multicatalyst reactions (MC)2R: One-pot synthesis of 3,4-dihydroquinolinones
-
A Rh/Pd/Cu catalyst system led to an efficient synthesis of dihydroquinolinones in one-pot, two operations. The reaction features the first triple metal-catalyzed transformations in one reaction vessel, without any intermediate workup. The conjugate-addition/amidation/amidation reaction sequence is highly modular, divergent, and practical.
- Zhang, Lei,Sonaglia, Lorenzo,Stacey, Jason,Lautens, Mark
-
supporting information
p. 2128 - 2131
(2013/06/05)
-
- Cu-Mn spinel oxide catalyzed regioselective halogenation of phenols and N-heteroarenes
-
A novel simple, mild chemo- and regioselective method has been developed for the halogenation of phenols using Cu-Mn spinel oxide as a catalyst and N-halosuccinimide as halogenating agent. In the presence of Cu-Mn spinel oxide B, both electron-withdrawing and electron-donating groups bearing phenols gave monohalogenated products in good to excellent yields with highest para-selectivity. The para-substituted phenol gave monohalogenated product with good yield and ortho-selectivity. N-Heteroarenes such as indoles and imidazoles also gave monohalogenated products with high selectivity. Unlike the copper-catalyzed halogenation, the present method works well with electron-withdrawing group bearing phenols and gives comparatively better yields and selectivity. The Cu-Mn spinel catalyst is robust and reused three times under optimized conditions without any loss in catalytic activity. Nonphenolics did not undergo this transformation.
- Singh, Parvinder Pal,Thatikonda, Thanusha,Kumar, K. A. Aravinda,Sawant, Sanghapal D.,Singh, Baldev,Sharma, Amit Kumar,Sharma,Singh, Deepika,Vishwakarma, Ram A.
-
experimental part
p. 5823 - 5828
(2012/09/05)
-
- TRPM8 receptor antagonists
-
Compounds acting as selective antagonists of Transient Receptor Potential cation channel subfamily M member 8 (hereinafter referred to as TRPM8), having formula: whereinR is selected from: - H, CN, NO2, SO2NH2, SO2NHR' and SO2NR'2, where R' is selected from linear or branched C1-C4 alkyl;X is selected from: - F, Cl, CH3, NH2 and OHY is selected from: - O, CH2, NH and SO2R1, R2, R3 and R4, indipendently one from the other, are selected from - H and linear or branched C1-C4 alkyl;Z is selected from: - NR6 and R6R7N+, where R6 and R7 indipendently one from the other, are selected from: ? H and linear or branched C1-C4 alkylR5 is a residue selected from: - H and linear or branched C1-C4 alkylHet is a heteroaryl group selected from - a substituted or not substituted pyrrolyl, a substituted or not substituted N-methylpyrrolyl, a substituted or not substituted thiophenyl, a substituted or not substituted furanyl and a substituted or not substituted pyridinyl. Said compounds are useful in the treatment of pathologies depending on TRPM8 activity such as pain, cancer, inflammation, ischaemia, neurodegeneration, stroke, psychiatric disorders, inflammatory conditions, urological disorders.
- -
-
Page/Page column 9
(2012/08/08)
-
- TRPM8 RECEPTOR ANTAGONISTS
-
Compounds acting as selective antagonists of Transient Receptor Potential cation channel subfamily M member 8 (hereinafter referred to as TRPM8), having formula (I), wherein R is selected from: - H, Br, CN, NO2, SO2NH2, SO2NHR' and SO2NR'2, where R' is selected from linear or branched C1-C4 alkyl; X is selected from: - F, C1, C1-C3 alkyl, NH2 and OH Y is selected from: - O, CH2, NH and SO2 R1 and R2, independently one from the other, are selected from - H, F and linear or branched C1-C4 alkyl; R3 and R4, independently one from the other, are selected from - H and linear or branched C1-C4 alkyl; Z is selected from: - NR6 and R6R7N+, where R6 and R7 independently one from the other, are selected from: ? H and linear or branched C1-C4 alkyl R5 is a residue selected from: - H and linear or branched C1-C4 alkyl Het is a heteroaryl group selected from - a substituted or not substituted pyrrolyl, a substituted or not substituted N- methylpyrrolyl, a substituted or not substituted thiophenyl, a substituted or not substituted furyl and a substituted or not substituted pyridinyl. Said compounds are useful in the prevention and treatment of pathologies depending on TRPM8 activity such as pain, inflammation, ischaemia, neurodegeneration, stroke, psychiatric disorders, inflammatory conditions and urological disorders.
- -
-
Page/Page column 14-15
(2012/08/08)
-
- Oxidative coupling of 2-naphthol and 2-alkoxy naphthalene by CuCl 2 and FeCl3 investigation of stereo selective induction effects of optically active compounds on the coupling process under Solid-state conditions and lonic liquid media
-
A new method for the 1,1'-binaphthalene-2,2'-diol and 1,1'-binaphthyl-2,2'- dialkylether by CuCl2 and FeCl3 under solid-state condition and ionic liquid is described. The stereo selectively coupling of 2-naphthol by CuCl2 and FeCl3 in presence of optically active amino acid is also studied. The optically purity of (S)-binaphthalene-2, 2'-diol in the presence of L-2-phenylglycine by FeCl3·H 2O in solid state and ionic liquid is 41 and 96 %, respectively.
- Tavana, Mahdie,Montazeri, Nasser,Imanzadeh, Gholamhassan
-
experimental part
p. 3097 - 3100
(2012/02/02)
-
- Pd(II)-catalyzed formal O-H insertion reactions of diazonaphthoquinones to acetic acid: Synthesis of 1,2-naphthalenediol derivatives
-
Pd(II)-catalyzed formal O-H insertion reaction of diazonaphthoquinones to acetic acid proceeded to afford 1,2-naphthalenediol monoacetates. In the presence of lithium halides, halonaphthols were obtained under the reaction conditions.
- Kitamura, Mitsuru,Kisanuki, Masato,Sakata, Rie,Okauchi, Tatsuo
-
scheme or table
p. 1129 - 1131
(2011/11/06)
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- Facile p-toluenesulfonic acid-promoted para-selective monobromination and chlorination of phenol and analogues
-
para-Regioselective bromination of phenol and analogues, promoted by p-toluenesulfonic acid, is achieved in high to excellent yields at room temperature with N-bromosuccinimide. Chlorination with N-chlorosuccinimide and catalysed by p-toluenesulfonic acid also gives para-chlorinated phenol analogues in good yields at room temperature. para-Bromination of phenol, promoted by p-toluenesulfonic acid, is achieved in excellent yields at room temperature with N-bromosuccinimide. p-Toluenesulfonic acid is also effective as a promoter of para-chlorination with N-chlorosuccinimide.
- Bovonsombat, Pakorn,Ali, Rameez,Khan, Chiraphorn,Leykajarakul, Juthamard,Pla-On, Kawin,Aphimanchindakul, Suraj,Pungcharoenpong, Natchapon,Timsuea, Nisit,Arunrat, Anchalee,Punpongjareorn, Napat
-
experimental part
p. 6928 - 6935
(2010/10/01)
-
- Modular synthesis of indoles from imines and o-dihaloarenes or o-chlorosulfonates by a Pd-catalyzed cascade process
-
A detailed study of the scope of a new Pd-catalyzed synthesis of indolesfrom 1,2-dihaloarenes and o-halobenzene sulfonates and imines is descri bed. The cascade reaction comprises an imine a-arylation ollowed by an intramolecular C-N bond-forming reaction promoted by the same Pd catalyst. The reaction with 1,2-dibromobenzene shows wide scope and allows the introduction of aryl, alkyl, and vinyl substituents at different positions of the five-membered ring of the indole. The regioselective synthesis of indoles substituted in the six-membered ring can be carried out by employing o-dihalobenzene derivatives with two different halogens, taking advantage of the different reactivities of I, Br, and Cl in oxidative addition reactions. This paper also introduces a method for the efficient cleavage of the N-t-butyl group, thus allowing for the preparation of N-H indoles through the same methodology. Finally, the reaction with o-halosulfonates has been studied. The best substrates are o-chlorononaflates, which lead to indoles in very high yield. The reaction is particularlyappropriate for the synthesis of the challenging 6-substituted indoles. In view of the availability of o-chlorophenols, which are direct precur sors of the chlorononaflates, this reaction represents an efficient entry into indoles substituted in the six-membered ring. The concept is illustrated by the preparation of a 4,6-disubstituted indole from naturally occurring anethole.
- Barluenga, Jose,Jimenez-Aquino, Agustin,Aznar, Fernando,Valdes, Carlos
-
supporting information; experimental part
p. 4031 - 4041
(2009/09/04)
-
- LEWIS ACID CATALYZED HALOGENATION OF ACTIVATED CARBON ATOMS
-
A practical and efficient method for halogenation of activated carbon atoms using readily available /V-haloimides and a Lewis acid catalyst has been disclosed. This methodology is applicable to a range of compounds and any halogen atom can be directly introduced to the substrate. The mild reaction conditions, easy workup procedure and simple operation make this method valuable from both an environmental and preparative point of view.
- -
-
Page/Page column 25-26
(2008/06/13)
-
- Lewis acid catalyzed highly selective halogenation of aromatic compounds
-
A simple and efficient procedure for the halogenation of aromatic compounds with NCS, NBS, NIS and NFSI in the presence of catalytic amount of ZrCl 4 is described. Chlorination, bromination, iodination and fluorination of various aromatic compounds are performed with high selectivity under mild reaction conditions. Georg Thieme Verlag Stuttgart.
- Zhang, Yanhua,Shibatomi, Kazutaka,Yamamoto, Hisashi
-
p. 2837 - 2842
(2007/10/03)
-
- Efficient halogenation of aromatic systems using N-halosuccinimides in ionic liquids
-
A simple, rapid and highly regioselective green protocol has been developed for the halogenation of aromatic systems with N-halosuccinimides using room temperature ionic liquids (ILs) as novel and recyclable reaction media to produce the corresponding halogenated aromatic compounds in high to quantitative yields. N-Halosuccinimides show enhanced reactivity in ionic liquids thereby reducing the reaction times dramatically and improving the yields substantially.
- Yadav,Reddy,Reddy,Basak,Narsaiah
-
-
- Environmentally benign chlorination and bromination of aromatic amines, hydrocarbons and naphthols
-
A simple and efficient procedure for chlorination and bromination of aromatic amines, hydrocarbons and naphthols by the action of aqueous hydrohalic acid and hydrogen peroxide is described. This environmentally clean and safe procedure involves in situ generation of the active halogen and its uncatalyzed reaction with the substrates in this study.
- Vyas, Punita V.,Bhatt, Anjani K.,Ramachandraiah, Gadde,Bedekar, Ashutosh V.
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p. 4085 - 4088
(2007/10/03)
-
- Process for producing azo pigment
-
A process for producing an azo pigment, which comprises coupling an aromatic diazonium compound with 3-hydroxy-2-naphthoic acid and at least one binaphthol and optionally, laking the resulting pigment.
- -
-
-
- Excited-State Proton-Transfer Kinetics: A Theoretical Model
-
The intersecting-state model is applied to excited state proton-transfer reactions.The results are consistent with those previously obtained for the analogous ground-state reactions.The transition-state bond order n* is similar in the ground and excited states: carbon acids have lower n* than nitrogen or oxygen acids.The mixing entropy parameter λ is found to be lower for excited-state than ground-state reactions.The mechanistic implications of this are discussed.
- Arnaut, Luis G.,Formosinho, Sebastiao J.
-
p. 685 - 691
(2007/10/02)
-
- Carbonyl Oxide Chemistry. The NIH Shift
-
Benzophenone oxide has been shown to oxidize 1-chloronaphthalene and p-xylene with accompanying NIH shift of chlorine and methyl, respectively.Similar oxidation of toluene leads to a mixture of o-,p-, and m-cresols while N-acetyl-L-phenylalanine ethyl ester is oxidized to the corresponding tyrosine derivative.The results are discussed in terms of their relationship to the "activation" of polycyclic aromatic hydrocarbons in polluted atmospheres and the possible production of mutagens/carcinogens.
- Kumar, S.,Murray, R. W.
-
p. 1040 - 1045
(2007/10/02)
-
- Naphthalene Tetrachlorides and Related Compounds. Part 11. trans-1,1,3,4-Tetrachlorotetralin-2-one, its Hydrate, and Related Compounds
-
X-Ray crystallographic analysis of 1,1,3,4-tetrachlorotetralin-2,2-diol has shown that this compound is the trans-isomer, which can be reversibly dehydrated to give trans-1,1,3,4-tetrachlorotetralin-2-one of previously unknown configuration, produced nearly quantitatively by chlorination of 2-naphthol in acetic acid.The 1H and 13C spectra of these compounds are reported; most of the angular-dependent coupling constants accord with expectations, the value of 3J(13C-1, 1H-3) being low, probably because the coupling path includes a carbonyl carbon atom.The rather high value of 3J(H-3, H-4) is discussed.The properties of some related ketodichlorides are reported.
- Brittain, Judith M.,Calvert, David J.,Mare, Peter B. D. de la,Jones, Tony C.,Newman, Paul A.,et al.
-
p. 247 - 254
(2007/10/02)
-
- HALOGENATION REGIOSELECTIVE EN SERIE AROMATIQUE-II CHLORATION DES NAPHTOLS ET LEURS ETHERS A L'AIDE DE REACTIFS METTANT EN JEU DES INTERACTIONS DU TYPE DONNEUR-ACCEPTEUR
-
The regispecific chlorination of naphtols by hexachlorocyclohexadienones as selective chlorinating reagents is described.The selectivity attained is better than that which we have obtained with phenol derivatives and confirms the importance of the donor-acceptor interaction between the reagent and the naphthol during the chlorination.
- Guy, Alain,Lemaire, Marc,Guette, Jean-Paul
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p. 2347 - 2354
(2007/10/02)
-
- Oxidation of Phenols, Pyrocatechols, and Hydroquinones to ortho-Quinones using Benzeneseleninic Anhydride
-
Benzeneseleninic anhydride has been used as a mild oxidising reagent to convert phenols into o-quinones including some examples where the p-position is unblocked.The method is limited to the production of o-quinones which are not susceptible to futher reaction.Pyrocatechols and hydroquinones can also be oxidised to the corresponding quinones in excellent yield using benzeneseleninic anhydride.
- Barton, Derek H. R.,Brewster, Andrew G.,Ley, Steven V.,Read, Christine M.,Rosenfeld, Moshe N.
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p. 1473 - 1476
(2007/10/02)
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- Substrate Specificity in Ester Hydrolysis by a New Water-Soluble Heterocyclophane
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A new water-soluble heterocyclophane, N,N,N',N',N'',N'',N''',N'''-octamethyl-2,11,20,29-tetraazaparacyclophanetetrammonium tetrafluoroborate (1), was found to catalyze the hydrolysis reaction of three aromatic chloroacetates, ClCH2CO2R , very effectively and specifically.The rate accelerations judged from the rate constant ratio of k2/k0 were 25+/-3 (7c), 6+/-0.5 (7b), or 2.6 (7a) at pH 8.10 in phosphate buffer and 18+/-2 (7c), 11+/-1 (7b), or 2.4 (7a) at pH 6.96 in phosphate buffer, strongly indicating that the "inclusion-electrostatic" catalyst 1 is more effective and discriminating than any of CTAB micelle, simple cyclodextrin inclusion, or an open-chain analogue (9).Very interestingly, however, a unique inhibition by 1 was found with a substrate of the α-chloro-β-naphthyl type (14), showing a rate constant ratio of kinh/k0=0.084+/-0.023 (1/12 deceleration).In order to elucidate the basis of this interesting discriminative catalysis or inhibition by 1, mechanistic studies were carried out.Temperature-jump experiments by the use of a model compound for substrate, sodium hydroxynaphthalenecarboxylate (11,12), had shown that the present host-guest inclusions are satisfactorily fast (kA=1.8E7 to 4.4E7 s-1 M-1; kD=1.6E4 to 3.8E4 s-1), allowing the host and guest to search for the most appropriate arrangement for the slow subsequent hydrolysis.The absence of any systematic correlation between log (k2/k0) vs. pKa of the leaving phenol or naphthol or a small basicity dependence of the N+-aryloxyl interaction leads to the conclusion that the very discriminative catalysis by 1 was developed mostly from specific substrate binding, in a sense that the N+-oxyanion interaction, at the transition state for the tetrahedral intermediate formation, remarkably depends on the substrate structure.The one-twelfth deceleration observed for 14 was, therefore, attributed to the inhibition of this N+-oxyanion interaction due to either the mechanism of "reverse binding" of the substrate or the "induced disfit".
- Tabushi, Iwao,Kimura, Yoshio,Yamamura, Kazuo
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p. 6486 - 6492
(2007/10/02)
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- CONDENSATION OF PHENOLS AND THEIR DERIVATIVES WITH AROMATIC COMPOUNDS IN THE PRESENCE OF ACIDIC AGENTS. V. REACTIONS OF CHLORINE-SUBSTITUTED NAPHTHOLS WITH BENZENE
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Substitution of the chlorine at position 1 by a phenyl residue occurs readily in the reaction of 1-chloro- and 1,4-dichloro-2-naphthols with benzene in the presence of aluminum chloride and hydrogen chloride. 4-Chloro-2-naphthol reacts with considerably great difficulty, giving a small yield of 4-phenyl-2-naphthol.The possibility of using a mixture of 4- and 2-chloro-1-naphthols for the production of 3-phenyl-1-naphthol was demonstrated.The possible reaction paths are discussed.
- Repinskaya, I. B.,Savel'ev, V. A.,Makarova, Z. S.,Koptyug, V. A.
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p. 1463 - 1466
(2007/10/02)
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