- Photocatalytic Atom-Transfer Radical Addition of Activated Chlorides to Alkenes
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A protocol for performing atom transfer radical addition of activated alkyl chlorides to alkenes is described. The reaction is promoted by blue light in the presence of an organic photocatalyst (3DPA2FBN), serving to generate free radicals, and a copper c
- Kostromitin, Vladislav S.,Zemtsov, Artem A.,Levin, Vitalij V.,Dilman, Alexander D.
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p. 5336 - 5340
(2021/11/03)
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- Esterification or Thioesterification of Carboxylic Acids with Alcohols or Thiols Using Amphipathic Monolith-SO3H Resin
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We have developed a method for the esterification of carboxylic acids with alcohols using amphipathic, monolithic-resin bearing sulfonic acid moieties as cation exchange functions (monolith-SO3H). Monolith-SO3H efficiently catalyzed the esterification of aromatic and aliphatic carboxylic acids with various primary and secondary alcohols (1.55.0 equiv) in toluene at 6080 °C without the need to remove water generated during the reaction. The amphipathic property of monolith-SO3H facilitates dehydration due to its capacity for water absorption. This reaction was also applicable to thioesterification, wherein the corresponding thioesters were obtained in excellent yield using only 2.0 equiv of thiol in toluene, although heating at 120 °C was required. Moreover, monolith-SO3H was separable from the reaction mixtures by simple filtration and reused for at least five runs without decreasing the catalytic activity.
- Ichihara, Shuta,Ishida, Moeka,Ito, Ryo,Kato, Ayumu,Monguchi, Yasunari,Nakamura, Shinji,Park, Kwihwan,Sajiki, Hironao,Takada, Hitoshi,Wakayama, Fumika,Yamada, Tsuyoshi,Yamada, Yutaro
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p. 2702 - 2710
(2022/01/19)
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- Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids**
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A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99 % yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state.
- Deng, Ruohan,Engle, Keary M.,Fu, Yue,Gao, Yang,Li, Zi-Qi,Liu, Peng,Tran, Van T.
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supporting information
p. 23306 - 23312
(2020/10/19)
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- Rhodium-Catalyzed Remote C(sp3)?H Borylation of Silyl Enol Ethers
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A rhodium-catalyzed remote C(sp3)?H borylation of silyl enol ethers (SEEs, E/Z mixtures) by alkene isomerization and hydroboration is reported. The reaction exhibits mild reaction conditions and excellent functional-group tolerance. This method is compatible with an array of SEEs, including linear and branched SEEs derived from aldehydes and ketones, and provides direct access to a broad range of structurally diverse 1,n-borylethers in excellent regioselectivities and good yields. These compounds are precursors to various valuable chemicals, such as 1,n-diols and aminoalcohols.
- Li, Jie,Qu, Shuanglin,Zhao, Wanxiang
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supporting information
p. 2360 - 2364
(2020/01/02)
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- Site-selective catalytic deaminative alkylation of unactivated olefins
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A catalytic deaminative alkylation of unactivated olefins is described. The protocol is characterized by its mild conditions, wide scope - including the use of ethylene as substrate -, and exquisite site-selectivity pattern for both a-olefins and internal olefins, thus unlocking a new catalytic platform to forge sp3-sp3 linkages, even in the context of late-stage functionalization.
- Sun, Shang-Zheng,Romano, Ciro,Martin, Ruben
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supporting information
p. 16197 - 16201
(2019/10/17)
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- Design and synthesis of affinity chromatography ligands for the purification of 5-hydroxyeicosanoid dehydrogenase
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Arachidonic acid (AA) is converted to biologically active metabolites by different pathways, one of the most important of which is initiated by 5-lipoxygenase (5-LO). 5-Hydroxyeicosatetraenoic acid (5-HETE), although possessing only weak biological activity itself, is oxidized to 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE), a potent chemoattractant for eosinophils and neutrophils. Our main goal is to determine how the biosynthesis of 5-oxo-ETE is regulated and to determine its pathophysiological roles. To achieve this task, we designed and synthesized affinity chromatography ligands for the purification of 5-hydroxyeicosanoid dehydrogenase (5-HEDH), the enzyme responsible for the formation of 5-oxo-ETE.
- Nagendra Reddy, Chintam,Grant, Gail E.,Ye, Qiuji,Powell, William S.,Patel, Pranav,Sivendran, Sashikala,Chourey, Shishir,Wang, Rui,Anumolu, Jaganmohan R.,Rokach, Joshua
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p. 116 - 125
(2016/12/22)
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- A resin-linker-vector approach to radiopharmaceuticals containing 18F: Application in the synthesis of O-(2-[18F]- Fluoroethyl)-L-tyrosine
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A Resin-linker-vector (RLV) strategy is described for the radiosynthesis of tracer molecules containing the radionuclide 18F, which releases the labelled vector into solution upon nucleophilic substitution of a polystyrene-bound arylsulfonate linker with [18F]-fluoride ion. Three model linker-vector molecules 7 a-c containing different alkyl spacer groups were assembled in solution from (4-chlorosulfonylphenyl)alkanoate esters, exploiting a lipase-catalysed chemoselective carboxylic ester hydrolysis in the presence of the sulfonate ester as a key step. The linker-vector systems were attached to aminomethyl polystyrene resin through amide bond formation to give RLVs 8 a-c with acetate, butyrate and hexanoate spacers, which were characterised by using magic-angle spinning (MAS) NMR spectroscopy. On fluoridolysis, the RLVs 8 a, b containing the longer spacers were shown to be more effective in the release of the fluorinated model vector (4-fluorobutyl)phenylcarbamic acid tert-butyl ester (9) in NMR kinetic studies and gave superior radiochemical yields (RCY≈60 %) of the 18F- labelled vector. The approach was applied to the synthesis of the radiopharmaceutical O-(2-[18F]-fluoroethyl)-L-tyrosine ([ 18F]-FET), delivering protected [18F]-FET in >90 % RCY. Acid deprotection gave [18F]-FET in an overall RCY of 41 % from the RLV. Copyright
- Topley, Amy C.,Isoni, Valerio,Logothetis, Thomas A.,Wynn, Duncan,Wadsworth, Harry,Gibson, Alex M. R.,Khan, Imtiaz,Wells, Neil J.,Perrio, Cécile,Brown, Richard C.D.
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supporting information
p. 1720 - 1725
(2013/02/25)
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- Eco-friendly molecular transformations catalyzed by a vitamin B 12 derivative with a visible-light-driven system
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A new bio-inspired system composed of a vitamin B12 derivative and Rose Bengal, catalyzed the dehalogenations of various toxic alkyl halides such as 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) via a noble-metal-free and visible-light-driven process. This system also catalyzed radical-involved organic reactions such as the 1,2-migration of acyl group via a tin-free process. The Royal Society of Chemistry.
- Tahara, Keishiro,Hisaeda, Yoshio
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supporting information; experimental part
p. 558 - 561
(2011/05/08)
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- Development of an enzyme-linked immunosorbent assay for the determination of the linear alkylbenzene sulfonates and long-chain sulfophenyl carboxylates using antibodies generated by pseudoheterologous immunization
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ELISA methods have been developed for screening contamination of water resources by linear alkyl benzene sulfonates (LAS) or the most immediate degradation products, the long chain sulfophenyl carboxylates, SPCs. The assay uses antibodies raised through pseudoheterologous immunization strategies using an equimolar mixture of two immunogens (SFA-KLH and 13C13-SPC-KLH) prepared by coupling N-(4-alkylpnenyl)sulfonyl-3-aminopropanoic acid (SFA) andp-(1-carboxy-13-tridecyl)-phenylsulfonic acid (13C13-SPC) to keyhole limpet hemocyanin (KLH). The immunizing haptens have been designed to address recognition versus two different epitopes of the molecule. The SFA hapten maximizes recognition of the alkyl moiety while preserving the complexity of the different alkyl chains present in the LAS technical mixture. The 13C13-SPC hapten addresses recognition of the common and highly antigenic phenylsulfonic group. The antisera raised using this strategy have been shown to be superior to those obtained through homologous immunization procedures using a single substance. By using an indirect ELISA format, LAS and long-chain SPCs can be detected down to 1.8 and 0.2 μg L-1, respectively. Coefficients of variation of 6 and 12% within and between assays, respectively, demonstrate immunoassay reproducibility. The assay can be used in media with a wide range of pH and ionic strength values. Preliminary experiments performed to assess matrix effects have demonstrated the potential applicability of the method as a screening tool to assess contamination by these types of surfactants in natural water samples.
- Ramon-Azcon, Javier,Galve, Roger,Sanchez-Baeza, Francisco,Marco, M.-Pilar
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- Novel hydrophobic Bronsted acidic ionic-liquids as efficient and reusable catalysts for organic reactions in water
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Novel Hydrophobic Bronsted acidic ionic liquids (HBAIL) were prepared and utilized as acid catalysts in organic reactions in water. HBAILs were demonstrated, for the first time, to be effective catalysts for Prins cyclization of styrene derivatives in water with a formaldehyde water solution. Many styrene derivatives could be successfully converted to the corresponding 1,3-dioxanes. Other dehydration reactions also proceeded well using HBAILs in water. After reactions, HBAILs could be easily recovered and reused without significant loss of activity. Copyright
- Gu, Yanlong,Ogawa, Chikako,Kobayashi, Shu
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p. 1176 - 1177
(2007/10/03)
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- Melanocortin receptor ligands
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Disclosed are MC-4 and/or MC-3 receptor ligands, the ligands having a structure according to Formula (I): wherein R2, R4, R4′, R5, R6, R6′, R7, R8, R8′, R9, R9′, R10, Ar, Z1, Z2, Z3, X, B, D, p, q, r and s are as described in the specification and claims, and optical isomers, diastereomers or enantiomers thereof; pharmaceutically-acceptable salts, hydrates, and biohydrolyzable esters, amides or imides thereof. Also disclosed are pharmaceutical compositions comprising the ligands of Formula (I), as well as methods of treating diseases mediate by the MC-4/MC-3 receptors, as described in the Detailed Descriptions section of the specification.
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Page/Page column 29
(2010/11/08)
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- First Kumada reaction of alkyl chlorides using N-heterocyclic carbene/palladium catalyst systems
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For the first time it is shown that N-heterocyclic carbenes are suitable ligands for the palladium-catalyzed coupling of alkyl chlorides with aryl Grignard reagents. A variety of simple as well as functionalized primary alkyl chlorides provide the corresponding alkyl benzenes in general in good to very good yield. By comparing the 1,3-dimesitylimidazol-2-ylidene (IMes) palladium(0) naphthoquinone complex with the previously known palladium phosphine catalyst for the model coupling reaction of 1-chlorohexane with phenylmagnesium bromide it is demonstrated that the new catalyst system is superior.
- Frisch, Anja C.,Rataboul, Franck,Zapf, Alexander,Beller, Matthias
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p. 403 - 409
(2007/10/03)
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- Palladium-catalyzed coupling of alkyl chlorides and Grignard reagents
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Chloroalkanes refined: A simple catalyst system renders the palladium-catalyzed coupling reaction of functionalized alkyl chlorides and Grignard reagents at room temperature (see example in scheme; PCy3 = tricyclohexylphosphane, NMP = N-methylpyrrolidinone).
- Frisch, Anja C.,Shaikh, Nadim,Zapf, Alexander,Belier, Matthias
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p. 4056 - 4059
(2007/10/03)
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- Design and synthesis of MMP inhibitors using N-arylsulfonylaziridine hydroxamic acids as constrained scaffolds
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The synthesis of cis- and trans-aziridine hydroxamic acid derivatives as MMP inhibitors is described using enantio- and diastereoselective methods for the formation of trisubstituted aziridines. Their preliminary inhibitory activity is reported and discus
- Hanessian, Stephen,Moitessier, Nicolas,Cantin, Louis-David
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p. 6885 - 6900
(2007/10/03)
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- Generation of Acyl Radicals from 1-Oxidoalkylidenechromium(0) Complexes by Treatment with Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) and Their Reactions with Olefins
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Tetramethylammonium pentacarbonyl(1-oxidoalkylidene)chromium(0) complexes are oxidized with bis(2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) to generate acyl radicals which react electron-deficient olefins, giving intermolecular addition products.
- Sakurai, Hidehiro,Narasaka, Koichi
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p. 2017 - 2020
(2007/10/02)
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- Generation of Alkyl Radicals from 1-Oxidoalkylidenechromium(0) Complexes by Oxidation with Manganese(III) 2-Pyridinecarboxylate and Their Reactions with Olefins
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Tetramethylammonium pentacarbonyl(1-oxidoalkylidene)chromium(0) complexes, prepared from the corresponding carbanion and hexacarbonylchromium(0), are oxidized with manganese(III) 2-pyridinecarboxylate to generate carbon-centered radicals which react with various olefins giving the intermolecular addition products.
- Narasaka, Koichi,Sakurai, Hidehiro
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p. 1269 - 1272
(2007/10/02)
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- Indirect Electroreductive Addition of Alkyl Radicals to Activated Olefins using a Nickel(II) Complex as an Electron-transfer Catalyst
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Indirect electroreductive intermolecular addition of primary and secondary alkyl radicals has been achieved using a nickel(II) complex as an electron-transfer catalyst.
- Ozaki, Shigeko,Matsushita, Hidenori,Ohmori, Hidenobu
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p. 649 - 652
(2007/10/02)
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- Preparation and opioid activity of analogues of the analgesic dipeptide 2,6-dimethyl-L-tyrosyl-N-(3-phenylpropyl)-D-alaninamide
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A number of analogues of the recently disclosed analgesic dipeptide 2,6- dimethyl-L-tyrosyl-D-alanine-phenylpropylamide (SC-39566, 2) were prepared. These analogues contained oxymethylene, aminomethylene, ketomethylene, bismethylene, and trans double bond (including vinyl fluoride) isosteric replacements for the amide bond between the D-alanine and phenylpropylamine units in 2. These compounds were tested in opioid binding assays and in the mouse writhing assay for analgesic activity. Though not as potent as 2, the oxymethylene, and trans double bond isosteres showed analgesic activity. The aminomethylene analogues also showed binding activity in subnanomolar concentrations at the μ receptor. The amide bond between 2,6-dimethyl-L- tyrosine and D-alanine units seems to be critical for opioid activity.
- Chandrakumar,Yonan,Stapelfeld,Savage,Rorbacher,Contreras,Hammond
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p. 223 - 233
(2007/10/02)
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- Aspects of Tautomerism. 13. Alkaline Hydrolysis of γ-, δ-, and ε-Keto Esters and their Desoxy Analogues. Geometrical Constraints on Keto Participation
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The rates of alkaline hydrolysis of methyl β-benzoylpropionate (I), methyl γ-benzoylbutyrate (II) and methyl δ-benzoylvalerate (III) decrease in the order I>II>III.Keto participation is the predominant pathway in the case of γ-keto esters.Evidence has also been obtained for keto participation in the case of δ-keto esters, whereas no such evidence is available in the case of ε-keto esters studied.
- Bhatt, M. Vivekananda,Ravindranathan, M.,Somayaji, Viswanatha,Rao, G. Venkoba
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p. 3170 - 3173
(2007/10/02)
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- The Synthesis of Medium-Sized Cyclic Lactams by the Intramolecular Friedel-Crafts Cyclization of Isocyanates. Formation of Novel Pyrazolobenzolactams
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A series of 4-ω-phenylalkyl substituted-1H-pyrazol-5-amines has been synthesized from the corresponding α-acetylphenylalkanenitriles and methylhydrazine.They were converted into the corresponding 5-isocyanates and cyclized under Friedel-Crafts conditions
- Butler, Donald E.,Alexander, Susan M.
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p. 1173 - 1177
(2007/10/02)
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