- Selective metalation of phenol-type proligands for preparative organometallic chemistry
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The selective C-metalation of phenol ester derived proligands is a readily applicable addition to state-of-the-art protocols toward cyclometalated structures, in particular of the base metals. The approach is demonstrated by the ortho-nickelation of a 1,10-phenanthroline based strong-field ligand platform that is a sought-after motif in the field of base-metal photochemistry.
- Berkefeld, Andreas,Fr?hlich, Markus,Kordan, Mike,H?rner, Gerald,Schubert, Hartmut
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Read Online
- Selective Bromination of β-Positions of Porphyrin by Self-Catalytic Behaviour of VOTPP: Facile Synthesis, Electrochemical Redox Properties and Catalytic Application
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Oxidovanadium(IV) complex of β-octabromo-meso-tetraphenylporphyrin, {[VIVO(TPPBr8)], 2} was synthesized by self-catalytic oxidative bromination of meso-tetraphenylporphyrinatooxidovanadium(IV) {[VIVO(TPP), 1} in excellent yield under mild conditions at 25 °C and its structure was confirmed by single crystal X-ray study. UV-Vis and 1H NMR spectra further confirmed that the meso-phenyl rings are not brominated and thus emphasizes on the selectivity as well as synthetic importance of this catalytic method. In the presence of substrates e. g. phenol derivatives, 1 biomimics the vanadium bromoperoxidase (VBPO) enzyme and catalyses the oxidative bromination of substrates in water at 25 °C. Remarkably, 2 also catalyses the oxidative bromination of phenol derivatives under similar reaction conditions with very high turnover frequency (TOF) values (ca. 29 s?1) along with its recyclability. It was found that 2 showed superior catalytic performance as compared to 1 because of its electron deficient nature due to electron withdrawing bromo substituents and robust saddle shaped nonplanar structure (further supported by DFT studies).
- Maurya, Mannar R.,Prakash, Ved,Avecilla, Fernando,Sankar, Muniappan
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p. 1685 - 1694
(2021/05/03)
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- Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
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A mild, metal-free bromination method of arenes has been developed using the combination of bis(trifluoroacetoxy)iodobencene and trimethylsilyl bromide. In situ-formed dibromo(phenyl)-λ3-iodane (PhIBr2) is proposed as the reactive intermediate. This methodology using PIFA/TMSBr has been applied with success to a great number of substrates (25 examples). The treatment of mono-substituted activated arenes led to para-brominated products (2u-z) in excellent 83-96% yields. Density functional theory calculations indicate a stepwise mechanism involving a double bromine addition followed by a type II dyotropic reaction with concomitant re-aromatization of the six-membered ring.
- Arrieta, Ana,Cossío, Fernando P.,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
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p. 2142 - 2150
(2020/03/11)
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- Regioselective monobromination of phenols with KBr and ZnAl–BrO3?–layered double hydroxides
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The regioselective mono-bromination of phenols has been successfully developed with KBr and ZnAl–BrO3?–layered double hydroxides (abbreviated as ZnAl–BrO3?–LDHs) as brominating reagents. The para site is much favorable and the ortho site takes the priority if para site is occupied. This reaction featured with excellent regioselectivity, cheap brominating reagents, mild reaction condition, high atom economy, broad substrate scope, and provided an efficient method to synthesize bromophenols.
- Wang, Ligeng,Feng, Chun,Zhang, Yan,Hu, Jun
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supporting information
(2020/02/22)
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- Synthesis of Ti-Al binary oxides and their catalytic application for C-H halogenation of phenols, aldehydes and ketones
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Traditional C–H halogenation of organic compounds often requires corrosive agent or harsh condition, and current researches are focused on the use of noble metals as catalyst. In order to give an efficient, benign, activity-adjustable and cost-effective system for halogenation, a series of Ti-Al mixed oxides are prepared as catalyst through sol-gel in this work. Characterizations reveal all catalysts contain more aluminum than titanium, but preparative conditions affect their composition and crystallinity. Monitoring of particle size, zeta potential and UV–vis of preparative solution reveals that formation of catalyst colloids undergoes chemical reaction, affecting catalyst morphology. In halogenation, all catalysts show moderate to high activities, copper chloride proves to be an effective halogen source rather than sodium chloride. The chlorination and bromination are better than iodization, phenol and ketone appear to be more appropriate substrates than aldehyde. Additionally, oxide backbone of catalyst is more durable than its organic components during recycling. This study may provide new catalytic materials for progress of C–H activation.
- Su, Peigen,Fan, Chao,Yu, Heng,Wang, Wanqin,Jia, Xin,Rao, Qifan,Fu, Chenxi,Zhang, Donghua,Huang, Benhua,Pan, Cheng,Zheng, Aqun,Sun, Yang
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- Trifluoromethyl aryl sulfonates (TFMS): An applicable trifluoromethoxylation reagent
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Fluorine is probably another favorite hetero-atom for incorporation into small molecules after nitrogen. Among many fluorine-containing groups, trifluoromethyl aryl ethers (ArOCF3) have unique properties in drug design and are difficult to be synthesized, and many different methods were developed to prepare them. A novel one-pot synthesis of o-iodine-aryl trifluoromethyl ethers (ArOCF3I) was described by the reaction of trifluoromethoxylation and iodination with trifluoromethyl aryl sulfonates (TFMS) in this manuscript. The reaction conditions were optimized by screening different solvents, crown ethers, substrates and the ratios and the yields of products were in moderate to high yields (up to 86%).
- Lei, Meng,Miao, Hang,Wang, Xueyuan,Zhang, Wen,Zhu, Chengjian,Lu, Xiaqiang,Shen, Jian,Qin, Yanru,Zhang, Haoyang,Sha, Sijia,Zhu, Yongqiang
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supporting information
p. 1389 - 1392
(2019/04/30)
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- Green halogenation reactions for (hetero)aromatic ring systems in alcohol, water, or no solvent
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A new method of brominating aromatic and heteroaromatic ring systems is investigated. The combination of hydrobromic acid as the halogen source, hydrogen peroxide as the oxidant, and ethanol, water, or no solvent are evaluated as greener conditions than those that have been previously published. The new conditions give high yields and good regioselectivity for a variety of substrates when the ring is activated by electron-donating groups or heteroatoms. Phenols, anisole, thiophenes, and pyrrole give comparable or superior results when compared to a traditional bromination by N-bromosuccinimide in tetrahydrofuran. Other nitrogen-containing heterocycles do not react under the conditions because they are protonated and hence deactivated; similarly, substrates with electron-withdrawing groups are not brominated. The reaction is very tolerant of a variety of functional groups.
- Kajorinne, Jessie K.,Steers, Jennifer C.M.,Merchant, Marnie E.,MacKinnon, Craig D.
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p. 1087 - 1091
(2018/11/25)
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- Axially chiral tridentate isoquinoline derived ligands for diethylzinc addition to aldehydes
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The synthesis and resolution of new tridentate isoquinoline-derived ligands has been developed. The key steps in the synthetic sequence include successive, chemo-selective Suzuki-Miyaura cross-couplings of 1,3-dichloroisoquinoline with suitable arylboronic acids. The new ligands prepared in this manner were resolved either via molecular complexation with N-benzylcinchonidinium chloride as with 1-[3-(2-hydroxyphenyl)isoquinolin-1-yl]naphthalen-2-ol or via chromatographic separation of its epimeric camphorsulfonates as for 1,3-bis-(2-hydroxynaphthalen-1-yl)isoquinoline. 4-tert-Butyl-2-chloro-6-[1-(2-hydroxymethylnaphthalen-1-yl)isoquinolin-3-yl]phenol was resolved by chiral semi-preparative HPLC. The application of these ligands in the diethylzinc addition to aldehydes was investigated. In certain cases, the desired secondary alcohols were obtained in high yield with excellent enantiomeric excess (ee > 99%) at low catalyst loading (1 mol%).
- Sweetman, Brian A.,Guiry, Patrick J.
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p. 5567 - 5581
(2018/08/09)
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- Research on unique masked ortho-benzoquinone, monohemiaminal: Synthesis and reactions
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Synthesis of ortho-benzoquinone monohemiaminals via the oxidative dearomatization/O-cyclization cascades of phenols bearing an ortho substituent derived from an amino alcohol with PIDA is described. The cascade reactions of substrates bearing a chiral substituent were found to proceed in a stereoselective manner. The Diels-Alder reactions of the ortho-benzoquinone monohemiaminals proceed in a highly stereoselective manner. The oxidative dearomatization/O-cyclization cascade affording the ortho-benzoquinone monohemiaminal had never been reported; hence, there is still ample scope for further investigation.
- Matsumoto, Yuri,Nakamura, Akihiko,Saito, Emi,Nakada, Masahisa
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p. 232 - 252
(2019/04/27)
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- NOVEL LIGAND COMPOUND AND TRANSITION METAL COMPOUND COMPRISING THE SAME
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The present invention relates to a novel ligand compound and a transition metal compound including the same. The transition metal compound with a novel structure according to the present invention can be used as a polymerization reaction catalyst when an olefin polymer is manufactured. The novel ligand compound has a structure in which two biphenyl-2-ols are connected to pyridine by methylene, respectively. An oxygen atom of biphenyl-2-ol is covalently bonded to the transition metal and a nitrogen atom of pyridine is coordinately bonded to the transition metal.COPYRIGHT KIPO 2018
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Paragraph 0143-0147
(2018/05/24)
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- Photoinduced Synthesis of Dibenzofurans: Intramolecular and Intermolecular Comparative Methodologies
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The SRN1 reaction has been used as a powerful tool for the synthesis of heterocycles, and only a few studies about photoinduced intramolecular cyclization to generate a new C-O bond by a radical pathway have been reported. This work introduces two strategies for the synthesis of substituted dibenzofurans by electron transfer (eT) reactions. The first one is a three-step process that comprises bromination of o-arylphenols, Suzuki-Miyaura cross-coupling and photoinduced cyclization in order to obtain the above-mentioned products. The second one is a metal-free procedure and does not require any photocatalyst. Different solvents were tested, and the yields ranged from low to moderate. A comparison was established between both methodologies, showing that the second one is the most suitable for the synthesis of dibenzofurans.
- Camargo Solórzano, Patricia,Brigante, Federico,Pierini, Adriana B.,Jimenez, Liliana B.
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supporting information
p. 7867 - 7877
(2018/06/11)
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- Selective and efficient generation of ortho-brominated para-substituted phenols in ACS-grade methanol
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The mono ortho-bromination of phenolic building blocks by NBS has been achieved in short reaction times (15-20 min) using ACS-grade methanol as a solvent. The reactions can be conducted on phenol, naphthol and biphenol substrates, giving yields of >86% on gram scale. Excellent selectivity for the desired mono ortho-brominated products is achieved in the presence of 10 mol % para-TsOH, and the reaction is shown to be tolerant of a range of substituents, including CH3/ F,and NHBoc.
- Georgiev, David,Saes, Bartholomews W.H.,Johnston, Heather J.,Boys, Sarah K.,Healy, Alan,Hulme, Alison N.
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- 2-bromine-4-tert-butylphenol preparing method
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The invention belongs to the field of chemical synthesis and provides a 2-bromine-4-tert-butylphenol preparing method. The method comprises the steps of providing raw materials P-tert-butylphenol, bromate and chlorite; placing P-tert-butylphenol, bromate and chlorite in an acid medium for oxidation reaction, wherein oxidation reaction is conducted for 4-8 h, and equation is shown in the specification. According to the method, the green oxidant and inorganic bromate are adopted as the bromine source, selectivity is high, the conversion rate of obtained 2-bromine-4-tert-butylphenol is as high as 99%, the yield is as high as 97%, environment pollution is avoided, and the environment protection idea is realized. Furthermore, operation is easy, reaction is easy to control, reaction time is short, the technology is reliable, and industrialization is facilitated.
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Paragraph 0026; 0035; 0048; 0049; 0050; 0051; 0052
(2016/11/28)
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- HETEROARYL DERIVATIVES AND USES THEREOF
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The present invention relates to antimalarial compounds and their use against protozoa of the genus Plasmodium, including drug-resistant Plasmodia strains. This invention further relates to compositions containing such compounds and a process for making the compounds.
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Page/Page column 0219
(2014/05/20)
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- Aryl Derivatives And Uses Thereof
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The present invention relates to antimalarial compounds and their use against protozoa of the genus Plasmodium, including drug-resistant Plasmodia strains. This invention further relates to compositions containing such compounds and a process for making the compounds.
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Paragraph 0147
(2014/05/20)
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- Controlling the catalytic aerobic oxidation of phenols
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The oxidation of phenols is the subject of extensive investigation, but there are few catalytic aerobic examples that are chemo- and regioselective. Here we describe conditions for the ortho-oxygenation or oxidative coupling of phenols under copper (Cu)-catalyzed aerobic conditions that give rise to ortho-quinones, biphenols or benzoxepines. We demonstrate that each product class can be accessed selectively by the appropriate choice of Cu(I) salt, amine ligand, desiccant and reaction temperature. In addition, we evaluate the effects of substituents on the phenol and demonstrate their influence on selectivity between ortho-oxygenation and oxidative coupling pathways. These results create an important precedent of catalyst control in the catalytic aerobic oxidation of phenols and set the stage for future development of catalytic systems and mechanistic investigations.
- Esguerra, Kenneth Virgel N.,Fall, Yacoub,Petitjean, Laurène,Lumb, Jean-Philip
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supporting information
p. 7662 - 7668
(2014/06/10)
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- Synthesis of tetrasubstituted alkenes through a palladium-catalyzed domino carbopalladation/C-H-activation reaction
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Helical tetrasubstituted alkenes (7) were obtained in a highly efficient way through a palladium-catalyzed domino-carbopalladation/CH-activation reaction of propargylic alcohols 6 in good to excellent yields. Electron-withdrawing- and electron-donating substituents can be introduced onto the upper and lower aromatic rings. The substrates (6) for the domino process were synthesized by addition of the lithiated alkyne (20) to various aldehydes (19); moreover, the substrates were accessible enantioselectively (in 95 % ee) by reduction of the corresponding ketone using the Noyori procedure. Copyright
- Tietze, Lutz F.,Hungerland, Tim,Duefert, Alexander,Objartel, Ina,Stalke, Dietmar
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supporting information; experimental part
p. 3286 - 3291
(2012/04/17)
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- Metal-free oxidative fluorination of phenols with [18F]fluoride
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The radiochemical synthesis of [18F]4-fluorophenols is based on phenol umpolung under oxidative conditions and direct nucleophilic fluorination with [18F]fluoride (see scheme, TBAF=tetra-n-butylammonium fluoride, TFA=trifluoroacetic acid). Readily available O-unprotected 4-tert-butyl phenols are used as precursors in this one-pot protocol. The reaction is completed in less than 30 minutes at room temperature and can be performed using standard or microfluidic technology. Copyright
- Gao, Zhanghua,Lim, Yee Hwee,Tredwell, Matthew,Li, Lei,Verhoog, Stefan,Hopkinson, Matthew,Kaluza, Wojciech,Collier, Thomas Lee,Passchier, Jan,Huiban, Mickael,Gouverneur, Véronique
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supporting information; experimental part
p. 6733 - 6737
(2012/08/28)
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- Aerobic oxybromination of phenols catalyzed by sodium nitrite under mild conditions
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An efficient catalytic system for oxybromination of phenols under mild conditions has been developed, which utilizes sodium nitrite as the catalyst, dioxygen or air as the terminal oxidant, aqueous hydrobromic acid or molecular bromine as the bromine resource. From both the atom-economic and environmental points of view, the developed protocol is expected to provide a valuable synthetic method for practical applications in laboratory or industry. Georg Thieme Verlag Stuttgart - New York.
- Xu, Li,Wang, Yong,Wen, Xin,Ding, Chengrong,Zhang, Guofu,Liang, Xinmiao
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supporting information; experimental part
p. 2265 - 2269
(2011/10/31)
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- Oxidative bromination reaction using vanadium catalyst and aluminum halide under molecular oxygen
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The vanadium-catalyzed oxidative bromination reaction of arenes, alkenes, and alkynes was performed in the presence of AlBr3 to provide an alternative method for conventional bromination using hazardous bromine. The catalytic cycle is formed under molecular oxygen, which is more advantageous to vanadium bromoperoxidase (VBrPO) requiring hydrogen peroxide as a terminal oxidant.
- Kikushima, Kotaro,Moriuchi, Toshiyuki,Hirao, Toshikazu
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supporting information; experimental part
p. 340 - 342
(2010/03/04)
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- Vanadium-catalyzed oxidative bromination promoted by Br?nsted acid or Lewis acid
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The oxidative bromination of arenes was induced by a vanadium catalyst in the presence of a bromide salt and a Br?nsted acid or a Lewis acid under molecular oxygen, which provides an eco-friendly bromination method as compared with a conventional bromination one with bromine. This catalytic reaction could be applied to the bromination of alkenes and alkynes to give the corresponding vic-bromides. Use of aluminum halide as a Lewis acid in place of a Br?nsted acid was demonstrated to provide a more practical protocol for the oxidative bromination. From ketones, α-bromination products were obtained. AlBr3 was found to serve as both a bromide source and a Lewis acid to induce the bromination smoothly. 51V NMR experiment showed that this catalytic bromination is likely to depend on the redox cycle of a vanadium catalyst under molecular oxygen.
- Kikushima, Kotaro,Moriuchi, Toshiyuki,Hirao, Toshikazu
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experimental part
p. 6906 - 6911
(2010/09/18)
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- CYCLIC CARBOXYLIC ACID RHODANINE DERIVATIVES FOR THE TREATMENT AND PREVENTION OF TUBERCULOSIS
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Disclosed are methods for the prevention or treatment of tuberculosis in a subject infected with Mycobacterium tuberculosis by administering rhodanine derivatives of formula (I), as well as some novel such compounds. Other embodiments are also disclosed.
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Page/Page column 27-28
(2010/08/22)
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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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- Synthesis of new type of macrocyclic lactones functionalized with different groups and investigation of their metal binding abilities
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New type of macrocyclic lactones functionalized with different groups were synthesized by reaction of the dihydroxy compounds such as 5a-d with suitable glycolyl chloride such as tri, tetra dicarboxylic acid dichloride derivatives. Their metal complexes with NaClO4.H2O, KCIO4 and Ba(ClO4)2.H2O were studied. Furthermore, their metal-pic-rate extraction studies with metal salts such as Na+, K+, Cu2+, Ni2+ and Hg2+ from aqueous phase to organic phase were attempted. All the structures of the ligands and complexes were confirmed by1H-, 13C-NMR, IR, UV-Vis, MS and elemental analyses methods.
- Ertul,Bayrakci
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experimental part
p. 493 - 502
(2009/10/09)
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- Highly enantioselective catalytic alkyl propiolate addition to aliphatic aldehydes
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A novel H8BINOL-based chiral ligand (S)-3 is found to catalyze the alkyl propiolate addition to aliphatic aldehydes in the presence of ZnEt2 and Ti(OiPr)4 at room temperature with excellent enantioselectivity (89-97% ee).
- Turlington, Mark,DeBerardinis, Albert M.,Pu, Lin
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supporting information; experimental part
p. 2441 - 2444
(2009/11/30)
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- Synthesis of 3-aryl-5-t-butylsalicylaldehydes and their chiral Schiff base compounds
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Six meta-substituted salicylaldehyde compounds have been prepared in 68-90% yields by the Suzuki-Miyaura coupling reaction using 3-bromo-5-t- butylsalicylaldehyde (1a) and arylboronic acids (2a-f) as reactants. Among the obtained products, 3-(4-fluorophenyl)-5-t-butylsalicylaldehyde (3b), 3-(4-methylphenyl)-5-t-butylsalicylaldehyde (3d), 3-(1-naphthyl)-5-t- butylsalicylaldehyde (3e), and 3-(2-naphthyl)-5-t-butylsalicylaldehyde (3f) have not been reported so far. A series of new Schiff base ligands (L1-L10) were obtained in 51-89% yields from these salicylaldehyde derivatives. Copyright Taylor & Francis Group, LLC.
- Liu, Hai-Bin,Wang, Mei,Wang, Ying,Gu, Qiang,Sun, Li-Cheng
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p. 3815 - 3826
(2008/02/10)
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- Copper(II) bromide: A simple and selective monobromination reagent for electron-rich aromatic compounds
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Copper(II) bromide was found to be a simple and efficient reagent for monobromination of electron-rich aromatic compounds at room temperature. The reaction proceeded smoothly with phenols, aryl alkyl ethers, and aromatic amines to afford the corresponding monobrominated product selectively in moderate to good yields. Copyright Taylor & Francis Group, LLC.
- Bhatt, Suchitra,Nayak, Sandip K.
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p. 1381 - 1388
(2008/02/01)
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- NOVEL COMPOUNDS, ISOMER THEREOF, OR PHARMACEUTICALLY ACCEPTABLE SALTS THEREOF AS VANILLOID RECEPTOR ANTAGONIST; AND PHARMACEUTICAL COMPOSITIONS CONTAINING THE SAME
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This present invention relates to novel compounds, isomer thereof or pharmaceutically acceptable salts thereof as vanilloid receptor (Vanilloid Receptor 1; VR1; TRPV1) antagonist; and a pharmaceutical composition containing the same. The present invention provides a pharmaceutical composition for preventing or treating a disease such as pain, inflammatory disease of the joints, neuropathies, HIV-related neuropathy, nerve injury, neurodegeneration, stroke, urinary bladder hypersensitivity including urinary incontinence, cystitis, stomach duodenal ulcer, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), fecal urgency, gastro-esophageal reflux disease (GERD), Crohn's disease, asthma, chronic obstructive pulmonary disease, cough, neurotic/allergic/inflammatory skin disease, psoriasis, pruritus, prurigo, irritation of skin, eye or mucous membrane, hyperacusis, tinnitus, vestibular hypersensitivity, episodic vertigo, cardiac diseases such as myocardial ischemia, hair growth-related disorders such as effluvium, alopecia, rhinitis, and pancreatitis.
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Page/Page column 104
(2010/11/28)
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- Tetrabromo hydrogenated cardanol: Efficient and renewable brominating agent
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(Chemical Equation Presented) 2,4,4,6-Tetrabromo-3-n-pentadecyl-2,5- cyclohexadienone (TBPCO) has been synthesized and used as a new efficient, convenient, and environmentally friendly brominating agent.
- Attanasi, Orazio A.,Berretta, Stefano,Favi, Gianfranco,Filippone, Paolino,Mele, Giuseppe,Moscatelli, Giada,Saladino, Raffaele
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p. 4291 - 4293
(2007/10/03)
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- Smooth muscle spasmolytic agents
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The present invention relates to smooth muscle spasmolytic agents, pharmaceutical compositions containing them and method of using said compounds and compositions for the treatment of urinary incontinence, and other smooth muscle contractility conditions. More particularly, the present invention relates to certain metabolically stabilized secondary amines having smooth muscle relaxing properties while avoiding, on administration to a mammal, adverse side effects such as prominent antimuscarinic, arrhythmogenic and cardiodepressive effects.
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- Galactose oxidase models: Solution chemistry, and phenoxyl radical generation mediated by the copper status
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Galactose oxidase (GO) is an enzyme that catalyzes two-electron oxidations. Its active site contains a copper atom coordinated to a tyrosyl radical, the biogenesis of which requires copper and dioxygen. We have recently studied the properties of electrochemically generated mononuclear CuII-phenoxyl radical systems as model compounds of GO. We present here the solution chemistry of these ligands under various copper and dioxygen statuses: N3O ligands first chelate CuII, leading, in the presence of base, to [CuII(ligand)(CH3CN)]+ complexes (ortho-tert-butylated ligands) or [(CuII)2(ligand) 2]2+ complexes (orthomethoxylated ligands). Excess copper-(II) then oxidizes the complex to the corresponding mononuclear Cu II-phenoxyl radical species. N2O2 tripodal ligands. in the presence of copper(II), afford directly a copper(II)-phenoxyl radical species. Addition of more than two molar equivalents of copper( II) affords a CuII-bis(phenoxyl) diradical species. The donor set of the ligand directs the reaction towards comproportionation for ligands possessing an N3O donor set, while disproportionation is observed for ligands possessing an N2O2 donor set. These results are discussed in the light of recent results concerning the self-processing of GO. A path involving copper(II) disproportionation is proposed for oxidation of the crosslinked tyrosinate of GO, supporting the fact that both copper(I) and copper(II) activate the enzyme.
- Michel, Fabien,Thomas, Fabrice,Hamman, Sylvain,Saint-Aman, Eric,Bucher, Christophe,Pierre, Jean-Louis
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p. 4115 - 4125
(2007/10/03)
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- Preparation of 3-aryl-substituted salicylaldehydes via Suzuki coupling
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An efficient method for the preparation of 3-arylsalicylaldehydes by palladium-catalyzed cross-coupling reaction of arylboronic acids and 3-bromo-5-tert-butylsalicylaldehyde is described. Parallel catalyst screening allowed rapid optimization of the reaction conditions.
- Zhuravel, Michael A.,Nguyen, Sonbinh T.
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p. 7925 - 7928
(2007/10/03)
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- Synthesis of substituted 2-bromo phenols using a novel bromination-dehydrobromination reaction
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Substituted 2-bromo-phenols can be synthesised by heating substituted cyclohexanones in neat diethyl dibromomalonate at 100°C. We discuss the efficiency of such a procedure and comment on the possible mechanism.
- Coumbarides,Dingjan,Eames,Weerasooriya
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p. 328 - 329
(2007/10/03)
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- Binuclear versus mononuclear copper complexes as catalysts for asymmetric cyclopropanation of styrene
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A number of (S)-(-)-2-amino-1,1-diaryl-1-propanol compounds have been synthesized. They were used to form the binuclear copper complexes through a spontaneous assembly of the individual components, the β-aminoalcohol, 2- hydroxy-5-methyl-1,3-benzenedialdehyde, and copper acetate monohydrate, in methanol. These binuclear complexes were examined as asymmetric catalysts for cyclopropanation of styrene by ethyl diazoacetate. Moderate improvement in enantioselectivity has been observed for the binuclear versus mononuclear copper complexes. The e.e. values up to 87% for trans and 93% for cis products and the ratio between trans and cis products up to 9:1 have been obtained.
- Cai, Lisheng,Mahmoud, Hussein,Han, Ying
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p. 411 - 427
(2007/10/03)
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- A process scheme involving transalkylation reactions to prepare o-bromophenol from phenol
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The bromination of phenol to o-bromophenol was carried out by protecting the para position with a tert-butyl group. The latter group was subsequently transferred to toluene using aluminum chloride as a catalyst. The resulting mixture of p-and m-tert-butyltoluene could be converted back to p-tert-butylphenol by transalkylation of the former with phenol in the presence of Engelhard, F-24. Thus, a process scheme based on transalkylation reactions as the intermediate steps has been proposed to synthesize o-bromophenol from phenol via p-tert-butylphenol. The effect of reaction parameters on overall conversion to and selectivity with respect to the desired product was studied for the transalkylation reactions involved in the process.
- Trivedi, Nikhil R.,Chandalia, Sampatraj B.
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- Synthesis of dinucleating phenanthroline-based ligands
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The phenolic bridged dinucleating phenanthroline-pyridine, phenanthroline-phosphine, phenanthroline-alcohol, and phenanthroline-imine ligands have been synthesized from 1,10-phenanthroline via key Stille and Suzuki cross couplings.
- Lam, Fung,Feng, MaoQi,Chan, Kin Shing
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p. 8377 - 8384
(2007/10/03)
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- Synthesis of Acyclic Dinucleating Phenanthroline-Pyridine and Phenanthroline-Phosphine Ligands
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The novel phenolic bridged dinucleating phenanthroline-pyridine 10 and phenanthroline-phosphine 15 ligands have been synthesized from 1,10-phenanthroline.
- Lam, Fung,Chan, Kin Shing,Liu, Bang-Ji
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p. 6261 - 6262
(2007/10/02)
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- ASYMMETRICALLY SUBSTITUTED CALIXARENES; A TWO-DIMENSIONAL 1H NMR STUDY OF A TETRAESTER DERIVATIVE IN THE CONE-CONFORMATION
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Several new chiral calixarenes with three or four different substituents in the p-position have been prepared by fragment condensation.Standard derivation procedures always led to the formation of mixtures of various conformational isomeres from which the derivative in the cone-conformation could be isolated only by preparative HPLC.For a tetraester derivative it was shown by two-dimensional 1H NMR spectroscopy, that due to the different substituents the cone-conformation is strongly distorted.The sodium complex of this tetraester, however, assumes a regular cone-conformation again.
- Zetta, Lucia,Wolff, Artur,Vogt, Walter,Platt, Karl-Ludwig,Boehmer, Volker
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p. 1911 - 1924
(2007/10/02)
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- Bromation regioselective en serie aromatique. I: Monobromation en position para de phenols et d'amines aromatiques par le tribromure de tetrabutylammonium
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The reaction of tetrabutylammonium tribromide (TBABr3) with phenols and aromatic amines in aprotic and non-basic solvents at 20 deg C gives exclusively the corresponding para-brominated compounds in high yields.A mechanism involving electrophilic substitution by the tribromide anion Br3- itself is suggested to account for the results, especially the regioselective para bromination.Key words: bromination, tetrabutylammonium tribromide, phenols, aromatic amines.
- Berthelot, Jacques,Guette, Catherine,Desbene, Paul-Louis,Basselier, Jean-Jacques,Chaquin, Patrick,Masure, Daniel
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p. 2061 - 2066
(2007/10/02)
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- THE INTERMEDIATES IN THE INTERACTION OF PHENOLS WITH N-BROMOSUCCINIMIDE
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Phenols react with N-bromosuccinimide to generate 2-bromocyclohexadienone-type intermediates that enolize to 2-bromophenols thermally or photolytically with a wide range of rate constants depending on the parent phenol.A trace amount of acids not only accelerates the rates of the formation and decomposition of the 2-bromodienones, it also promotes the rearrangement of the 2-bromodienones to cross-conjugated 4-bromocyclohexadienones.The enolization of these last compounds affords 4-bromophenols.The occurrence of autocatalysis in dienone decompositions arising from more acidic bromophenols is also established.The reaction is assumed to occur by a bromophilic attack of phenols on the N-Br bond to form unstable hypobromites that rapidly rearrange to the 2-bromocyclohexadienone intermediates.The quantum yield of the photodecomposition of 2-bromo-(2H)-naphthalene-1-one in the vicinity of 365 nm was determined to be unity.
- Chow, Yuan L.,Zhao, Da-Chuan,Johansson, Carl J.
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p. 2556 - 2564
(2007/10/02)
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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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- Pocket Porphyrins with Intramolecular Ligands
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The synthesis of porphyrins 12 with a pocket and an intramolecularly attached pyridine ring as a ligand is described.The key step involves porphyrin cyclization of 1,3,5-benzenetricarboxylic trisester (10), building up the pocket, and 3-pyridine (5), introducing the pyridine ligand, with four equivalents of pyrrole (11).Preparation procedures for the starting materials are described; NMR data of the target porphyrins 12 and their assignments are tabulated.
- Orth, Ulrich,Pfeiffer, Heinz-Peter,Breitmaier, Eberhard
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p. 3507 - 3514
(2007/10/02)
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- Complete Kinetic Analysis of the Thermal Stereomutations of (+)-(1S,2S,3R)-r-1-Cyano-t-2-methyl-1,2,t-3-trideuteriocyclopropane
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(+)-(1S,2S,3R)-r-1-Cyano-t-2-methyl-1,2,t-3-trideuteriocyclopropane has been synthesized in optically pure form.The kinetic of thermal stereomutations which interconvert this and seven other isomeric cyclopropanes have been followed: at 335.4 deg C in the gas phase, the title compound undergoes stereomutations with rate constants (x105 s) k1 = 0.55, k2 = 0.61, k3 = 0.10, k12 = 0.88, k13 = 0.083, and k23 = 0; the cis-1-cyano-2-methyl-1,2,3-trideuteriocyclopropanes exhibit stereomutation rate constants (x105 s) k'1 = 0.62, k'2 = 0.69, k'3 = 0.15, k'12 = 1.31, k'13 = 0.09, and k'23 = 0.While cyclopropanes 1,2-disubstituted with potent radical-stabilizing groups such as phenyl, cyano, and vinyl give stereomutation products by way of C(1)-C(2) bond cleavage only, the deuterium-labeled 1-cyano-2-methylcyclopropanes experience thermal stereomutations consistent with the intermediacy of two distinct trimethylene diradicals, one formed through cleavage of the C(1)-C(2) bond, the other by breaking C(1)-C(3).
- Baldwin, John E.,Carter, Charles G.
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p. 1362 - 1368
(2007/10/02)
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