- Electrochemical Intramolecular Reductive Cyclisation Catalysed by Electrogenerated Ni(cyclam)(2+)
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The intramolecular cyclisation of a series of o-halogenated aromatic compounds containing unsaturated side-chains has been developed using electrosynthesis, combined with organometallic catalysis by Ni(cyclam)Br2.
- Olivero, Sandra,Clinet, Jean Claude,Dunach, Elisabet
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Read Online
- Synthesis of benzofurans in ionic liquid by a PdCl2-catalyzed intramolecular Heck reaction
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PdCl2-catalyzed intramolecular Heck reaction was conducted in ionic liquid, 1-n-butyl-3-methylimidazolium tetraborate ([BMIm] BF4), substituted benzofurans were obtained in modest to satisfactory yields. The ionic liquid containing Pd catalyst can be used four times with a little loss of activity.
- Xie, Xingang,Chen, Bo,Lu, Jiangping,Han, Junjie,She, Xuegong,Pan, Xinfu
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Read Online
- The Synthesis of 3-Methylene-2,3-dihydrobenzofuran Stabilised as its Tricarbonylchromium Complex
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The title complex has been synthesised in two steps by the palladium-catalysed coupling of o-lithiated η6-fluorobenzenetricarbonylchromium(0) with 2-bromo-1-trimethylsiloxyprop-2-ene and cyclisation of the product with fluoride ion.
- Beswick, Paul J.,Widdowson, David A.
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Read Online
- Electrochemical partial fluorination of organic compounds. 74. Efficient anodic synthesis of 2-fluoro- and 2,3-difluoro-2,3-dihydrobenzofuran derivatives
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Anodic fluorination of 3-substituted benzofuran derivatives in a variety of fluoride salts resulted in the formation of three fluorinated products; two stereoisomers of 2,3-difluoro-2,3-dihydrobenzofuran (cis and trans) and cis-2-fluoro-3-hydroxy-2,3-dihydrobenzofuran derivatives. Dehydrofluorination of the main products, cis-difluoro derivatives, furnished the nonaromatic 2-fluoro-3-benzofuranyledene derivatives instead of the aromatic 2-fluorobenzofuran derivatives.
- Dawood, Kamal M.,Fuchigami, Toshio
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Read Online
- Enantio- and Diastereoselective, Complete Hydrogenation of Benzofurans by Cascade Catalysis
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We report an enantio- and diastereoselective, complete hydrogenation of multiply substituted benzofurans in a one-pot cascade catalysis. The developed protocol facilitates the controlled installation of up to six new defined stereocenters and produces architecturally complex octahydrobenzofurans, prevalent in many bioactive molecules. A unique match of a chiral homogeneous ruthenium-N-heterocyclic carbene complex and an in situ activated rhodium catalyst from a complex precursor act in sequence to enable the presented process.
- Gallagher, Timothy,Glorius, Frank,Hu, Tianjiao,Moock, Daniel,Wagener, Tobias
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supporting information
p. 13677 - 13681
(2021/05/10)
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- Rhodium-Catalyzed Intermolecular Cyclopropanation of Benzofurans, Indoles, and Alkenes via Cyclopropene Ring Opening
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The generation of metal carbenoids via ring opening of cyclopropenes by transition metals offers a simple entry into highly reactive intermediates. Herein, we describe a diastereoselective intermolecular rhodium-catalyzed cyclopropanation of heterocycles and alkenes using cyclopropenes as carbene precursors with a low loading of a commercially available rhodium catalyst. The reported method is scalable and could be performed with catalyst loadings as low as 0.2 mol %, with no impact to the reaction yield or selectivity.
- Jeyaseelan, Rubaishan,Lautens, Mark,Ross, Rachel J.
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- Synthesis of benzofurans from the cyclodehydration of α-phenoxy ketones mediated by Eaton’s reagent
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Cyclodehydration of α-phenoxy ketones promoted by Eaton’s reagent (phosphorus pentoxide–methanesulfonic acid) is used to prepare 3-substituted or 2,3-disubstituted benzofurans with moderate to excellent yields under mild conditions. The method provides a facile access to benzofurans from readily available starting materials such as phenols and α-bromo ketones. The reaction is highly efficient, which is attributed to the good reactivity and fluidity of Eaton’s reagent. The reaction can be applied to prepare naphthofurans, furanocoumarins, benzothiophenes, and benzopyrans.
- Ma, Lin,Ma, Zhanwei,Zhang, Min,Zhou, Min
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p. 426 - 436
(2020/03/23)
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- Decarboxylation method for heterocyclic carboxylic acid compounds
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The invention relates to a decarboxylation method for heterocyclic carboxylic acid compounds. The method comprises the following steps: dissolving the heterocyclic carboxylic acid compounds in an aprotic polar solvent N,N-dimethylformamide, and performing decarboxylation at 85-150 DEG C with an organic acid as a catalyst. The method in the invention allows the yield of decarboxylation products obtained after a reaction to be higher than the yield of the products obtained through decarboxylation methods in the prior art, and does not need an expensive metal catalyst; and the solvent (DMF) in the present invention is more stable than DMSO, is not prone to decompose at a high temperature, and it can be recycled, so the cost is reduced. The method has the advantages of simple operation process, zero pollution, greenness, environmental protection and excellent application prospect.
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Paragraph 0032; 0033; 0041
(2019/05/11)
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- Microwave-Assisted Domino Heck Cyclization and Phosphorylation: Synthesis of Phosphorus Containing Heterocycles
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A domino [Pd]-catalyzed intramolecular Heck cyclization followed by intermolecular phosphorylation, for the construction of phosphorus containing heterocyclic compounds, is presented. Notably, the process is accelerated by microwave heating conditions and enabled the construction of C–C and C–P bonds in short reaction times.
- Ramesh, Karu,Satyanarayana, Gedu
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p. 3856 - 3866
(2019/06/21)
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- A vicarious, one-pot synthesis of benzo- and naphthofurans: Applications to the syntheses of stereumene B and paeoveitols
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An interesting albeit unexpected deviation during attempted Tanabe γ-lactone annulation on 4-hydroxycyclohexanones has led to a general, one-pot synthesis of benzofurans and naphtho[2,3–b]furans from readily assembled precursors. The utility of this adaptable methodology has been demonstrated through concise syntheses of natural products, stereumene B, paeoveitol D and (±)-paeoveitol.
- Rashid, Showkat,Bhat, Bilal A.,Mehta, Goverdhan
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supporting information
p. 1122 - 1125
(2019/03/26)
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- Mercapto-amide boronic acid derivative and application thereof as MBL (metal beta-lactamase) and/or SBL (serine beta-lactamase) inhibitor
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The invention provides a compound of a formula (I) shown in the specification, or a conformational isomer, or an optical isomer or a pharmaceutically acceptable salt thereof. The compound of the formula (I) shown in the specification has excellent broad-spectrum inhibitory activity on MBL (metal beta-lactamase) and/or SBL (serine beta-lactamase), and can be used for preparing MBL and/or SBL inhibitors. Moreover, the compound disclosed by the invention has excellent antibacterial activity on multiple drug-resistant bacteria and is capable of reversing drug resistance of carbapenem drug-resistant bacteria, and the antibacterial effect of the compound is prior to those of positive control products such as L-captopril and tazobactam. The compound disclosed by the invention has very great potential in preparation of MBL/SBL dual inhibitors and medicines reversing drug resistance of carbapenem drug-resistance bacteria.
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- Structure-based development of (1-(3′-Mercaptopropanamido)methyl)boronic Acid Derived Broad-Spectrum, Dual-Action Inhibitors of Metallo- And Serine-β-lactamases
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The emergence and spread of bacterial pathogens acquired metallo-β-lactamase (MBL) and serine-β-lactamase (SBL) medicated β-lactam resistance gives rise to an urgent need for the development of new dual-action MBL/SBL inhibitors. Application of a pharmacophore fusion strategy led to the identification of (2′S)-(1-(3′-mercapto-2′-methylpropanamido)methyl)boronic acid (MS01) as a new dual-action inhibitor, which manifests broad-spectrum inhibition to representative MBL/SBL enzymes, including the widespread VIM-2 and KPC-2. Guided by the VIM-2:MS01 and KPC-2:MS01 complex structures, further structural optimization yielded new, more potent dual-action inhibitors. Selectivity studies indicated that the inhibitors had no apparent inhibition to human angiotensin-converting enzyme-2 and showed selectivity across serine hydrolyases in E. coli and human HEK293T cells labeled by the activity-based probe TAMRA-FP. Moreover, the inhibitors displayed potentiation of meropenem efficacy against MBL- or SBL-positive clinical isolates without apparent cytotoxicity. This work will aid efforts to develop new types of clinically useful dual-action inhibitors targeting MBL/SBL enzymes.
- Wang, Yao-Ling,Liu, Sha,Yu, Zhu-Jun,Lei, Yuan,Huang, Meng-Yi,Yan, Yu-Hang,Ma, Qiang,Zheng, Yang,Deng, Hui,Sun, Ying,Wu, Chengyong,Yu, Yamei,Chen, Qiang,Wang, Zhenling,Wu, Yong,Li, Guo-Bo
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p. 7160 - 7184
(2019/08/28)
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- Trimethylphosphate as a Methylating Agent for Cross Coupling: A Slow-Release Mechanism for the Methylation of Arylboronic Esters
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A methyl group on an arene, despite its small size, can have a profound influence on biologically active molecules. Typical methods to form a methylarene involve strong nucleophiles or strong and often toxic electrophiles. We report a strategy for a new, highly efficient, copper and iodide co-catalyzed methylation of aryl- and heteroarylboronic esters with the mild, nontoxic reagent trimethylphosphate, which has not been used previously in coupling reactions. We show that it reacts in all cases tested in yields that are higher than those of analogous copper-catalyzed reactions of MeOTs or MeI. The combination of C-H borylation and this methylation with trimethylphosphate provides a new approach to the functionalization of inert C-H bonds and is illustrated by late-stage methylation of four medicinally active compounds. In addition, reaction on a 200 mmol scale demonstrates reliability of this method. Mechanistic studies show that the reaction occurs by a slow release of methyl iodide by reaction of PO(OMe)3 with iodide catalyst, rather than the typical direct oxidative addition to a metal center. The low concentration of the reactive electrophile enables selective reaction with an arylcopper intermediate, rather than nucleophilic groups on the arylboronate, and binding of tert-butoxide to the boronate inhibits reaction of the electrophile with the tert-butoxide activator to form methyl ether.
- He, Zhi-Tao,Li, Haoquan,Haydl, Alexander M.,Whiteker, Gregory T.,Hartwig, John F.
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supporting information
p. 17197 - 17202
(2018/12/14)
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- Exogenous-oxidant-free electrochemical oxidative C-H sulfonylation of arenes/heteroarenes with hydrogen evolution
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An efficient and environmentally benign electrochemical oxidative radical C-H sulfonylation of arenes/heteroarenes was developed in this work. A series of significant diarylsulfones were prepared under mild catalyst- and exogenous-oxidant-free reaction conditions, which efficiently avoid the issues of desulfonylation or over-reduction of sulfonyl groups.
- Yuan, Yong,Yu, Yi,Qiao, Jin,Liu, Pan,Yu, Banying,Zhang, Wukun,Liu, Huilin,He, Min,Huang, Zhiliang,Lei, Aiwen
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supporting information
p. 11471 - 11474
(2018/10/20)
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- Ligand-Free Heck Reactions of Aryl Iodides: Significant Acceleration of the Rate through Visible Light Irradiation at Ambient Temperature
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A mild Heck reaction of aryl iodides and olefins was realized by the cooperation of a palladium and a photoredox catalyst under the irradiation of visible light. This protocol works well to synthesize stilbenes with high Z/E ratios and (E)-cinnamates in the absence of ligands at ambient temperature. Control experiments revealed that palladium salt, visible light and photoredox catalyst were all crucial for the achievement of this cross-coupling under mild conditions. (Figure presented.).
- Zhang, Heng,Huang, Xueliang
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supporting information
p. 3736 - 3742
(2016/12/16)
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- Antagonistic Effect of Acetates in C–N Bond Formation with In Situ Generated Diazonium Salts: A Combined Theoretical and Experimental Study
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The mechanism of the copper-catalyzed arylation of nitrogen heterocycles using anilines via diazonium salts has been studied by combining DFT and experimental data. A CuI/CuIIIredox mechanism is proposed. Our study has revealed the multiple roles of the acid/base couple AcOH/AcO–. An in situ formed triazene species maintains a low concentration of diazonium salts in the reaction medium, which ensures limited formation of decomposition products. The results of DFT calculations have explained the lower reactivity of imidazole nucleophiles as compared with pyrazole in the arylation reaction.
- Fabre, Indira,Perego, Luca Alessandro,Bergès, Julien,Ciofini, Ilaria,Grimaud, Laurence,Taillefer, Marc
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p. 5887 - 5896
(2016/12/18)
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- Substrate-Tuned Catalysis of the Radical S-Adenosyl- L -Methionine Enzyme NosL Involved in Nosiheptide Biosynthesis
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NosL is a radical S-adenosyl-L-methionine (SAM) enzyme that converts L-Trp to 3-methyl-2-indolic acid, a key intermediate in the biosynthesis of a thiopeptide antibiotic nosiheptide. In this work we investigated NosL catalysis by using a series of Trp analogues as the molecular probes. Using a benzofuran substrate 2-amino-3-(benzofuran-3-yl)propanoic acid (ABPA), we clearly demonstrated that the 5′-deoxyadenosyl (dAdo) radical-mediated hydrogen abstraction in NosL catalysis is not from the indole nitrogen but likely from the amino group of L-Trp. Unexpectedly, the major product of ABPA is a decarboxylated compound, indicating that NosL was transformed to a novel decarboxylase by an unnatural substrate. Furthermore, we showed that, for the first time to our knowledge, the dAdo radical-mediated hydrogen abstraction can occur from an alcohol hydroxy group. Our study demonstrates the intriguing promiscuity of NosL catalysis and highlights the potential of engineering radical SAM enzymes for novel activities.
- Ji, Xinjian,Li, Yongzhen,Ding, Wei,Zhang, Qi
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supporting information
p. 9021 - 9024
(2015/08/03)
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- Pd-Catalyzed Highly Regio- and Stereoselective Formation of C-C Double Bonds: An Efficient Method for the Synthesis of Benzofuran-, Dihydrobenzofuran-, and Indoline-Containing Alkenes
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A highly regio- and stereoselective C-C double bond formation reaction via Pd-catalyzed Heck-type cascade process with N-tosylhydrazones has been developed. Various N-tosylhydrazones derived from both ketones and aldehydes are found to be efficient substrates to provide di- and trisubstituted olefins with high regio- and stereoselectivity. Furthermore, this reaction has a good functional group tolerance and different benzofuran-, dihydrobenzofuran-, and indoline-containing alkene products were obtained with high selectivity.
- Gao, Yang,Xiong, Wenfang,Chen, Huoji,Wu, Wanqing,Peng, Jianwen,Gao, Yinglan,Jiang, Huanfeng
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p. 7456 - 7467
(2015/08/18)
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- Copper-catalyzed cross-coupling of boronic esters with aryl iodides and application to the carboboration of alkynes and allenes
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Copper-catalyzed Suzuki-Miyaura-type cross-coupling and carboboration processes are reported. The cross-couplings function well with a variety of substituted aryl iodides and aryl boronic esters and allows for orthogonal reactivity compared to palladium-catalyzed processes. The carboboration method includes both alkynes and allenes and provides access to highly substituted and stereodefined vinyl boronic esters. The alkyne carboboration method is highlighted in the simple one-pot synthesis of Tamoxifen. Cross-Cu-pling: The title cross-couplings function well with a variety of substituted aryl iodides and aryl boronic esters and allows for reactivity orthogonal to that of the palladium-catalyzed processes. The title carboboration method includes both alkynes and allenes and provides access to highly substituted and stereodefined vinyl boronic esters. The alkyne carboboration method is highlighted in a simple one-pot synthesis of Tamoxifen.
- Zhou, Yiqing,You, Wei,Smith, Kevin B.,Brown, M. Kevin
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supporting information
p. 3475 - 3479
(2014/04/03)
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- Iron-catalysed borylation of arenediazonium salts to give access to arylboron derivatives via aryl(amino)boranes at room temperature
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Complementary to previously described Miyaura borylation methods, a new access to boron derivatives via aryl(amino)boranes is described. Direct coupling between aryldiazonium salts and diisopropylaminoborane is catalysed by 0.1% ferrocene leading to the formation of a carbon-boron bond. The obtained aryl(amino)boranes could eventually then be transformed into boronic acids, boronates or borates. Copyright
- Marciasini, Ludovic D.,Richy, Nicolas,Vaultier, Michel,Pucheault, Mathieu
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p. 1083 - 1088
(2013/05/21)
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- SUBSTITUTED PYRIDINE DERIVATIVES AS FABI INHIBITORS
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The present invention provides substituted pyridine derivatives of formula (I), which may be therapeutically useful as as anti-bacterial agents, more particulalrly FabI inhibitors. Formula(I) in which R1 to R5 and L have the meanings given in the specification, and pharmaceutically acceptable salts thereof that are useful in the treatment and prevention in diseases or disorder, in particular their use in diseases or disorder where there is an advantage anti-bacterial agents, more particularly FabI inhibitors. The present invention also provides methods for synthesizing and administering the FabI inhibitor compounds. The present invention also provides pharmaceutical formulations comprising at least one of the FabI inhibitor compounds together with a pharmaceutically acceptable carrier, diluent or excipient therefor.
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Page/Page column 43
(2013/06/27)
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- Synthetic models related to methoxalen and menthofuran-cytochrome P450 (CYP) 2A6 interactions. Benzofuran and coumarin derivatives as potent and selective inhibitors of CYP2A6
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Human microsomal cytochrome P450 (CYP) 2A6 contributes extensively to nicotine detoxication but also activates tobacco-specific procarcinogens to mutagenic products. We prepared a series of benzofuran and coumarin derivatives that have inhibitory effects on the activity of human CYP2A6. The reported compounds methoxalen and menthofuran had potent inhibitory effects on the activity of CYP2A6 with IC50 values of 0.47 μM and 1.27 μM, respectively. Synthetic benzofuran (4-methoxybenzofuran: IC50=2.20 μM) and coumarin (5-methoxycoumarin: IC50=0.13 μM and 6-methoxycoumarin: IC50=0.64 μM) derivatives, which have more selective effects than those of methoxalen and menthofuran, exhibited comparable activities against CYP2A6. These compounds can be used as a lead compounds in the design of CYP2A6 inhibitor drugs to reduce smoking and tobacco-related cancers.
- Yamaguchi, Yuki,Akimoto, Ichie,Motegi, Kyoko,Yoshimura, Teruki,Wada, Keiji,Nishizono, Naozumi,Oda, Kazuaki
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p. 997 - 1001
(2013/11/19)
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- Palladium-catalyzed synthesis of terminal acetals via highly selective anti-Markovnikov nucleophilic attack of pinacol on vinylarenes, allyl ethers, and 1,5-dienes
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A palladium-catalyzed reaction of vinylarenes, allyl ethers, and 1,5-dienes with pinacol proceeded via a selective anti-Markovnikov nucleophilic attack to afford corresponding terminal acetals as major products. The bulkiness of pinacol was found to be critical in controlling the regioselectivity. The Royal Society of Chemistry 2012.
- Yamamoto, Mayumi,Nakaoka, Sonoe,Ura, Yasuyuki,Kataoka, Yasutaka
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supporting information; experimental part
p. 1165 - 1167
(2012/02/04)
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- Ruthenium NHC catalyzed highly asymmetric hydrogenation of benzofurans
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H2-O-T! Aromatic O-heterocycles are a challenging substrates for asymmetric hydrogenation (H2). An in situ formed chiral N-heterocyclic carbene (NHC) ruthenium complex allows the high yielding, completely regioselective, and highly asymmetric hydrogenation of substituted benzofurans at room Temperature, giving valuable 2,3-dihydrobenzofurans (see scheme). Copyright
- Ortega, Nuria,Urban, Slawomir,Beiring, Bernhard,Glorius, Frank
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p. 1710 - 1713
(2012/04/05)
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- Highly asymmetric synthesis of (+)-corsifuran A. Elucidation of the electronic requirements in the Ruthenium-NHC catalyzed hydrogenation of benzofurans
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A short and efficient synthesis of ent-corsifuran A by a highly asymmetric hydrogenation of a benzofuran precursor is reported. In addition, the electronic influence of the substituents on the asymmetric hydrogenation of benzofurans is provided. Whereas the hydrogenation of electron-deficient benzofurans was achieved under very mild conditions, the presence of electron-donating groups in the benzofuran required harsher reaction conditions for achieving full conversion to the 2,3-dihydrobenzofuran.
- Ortega, Nuria,Beiring, Bernhard,Urban, Slawomir,Glorius, Frank
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p. 5185 - 5192
(2012/07/31)
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- Cationic palladium-catalyzed [5 + 2] annulation of 2-acylmethoxyarylboronic acids and allenoates: Synthesis of 1-benzoxepine derivatives
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The 1-benzoxepine derivatives were synthesized conveniently by cationic palladium-catalyzed [5 + 2] annulation reaction of 2-acylmethoxyarylboronic acids with allenoates in high yields. This annulation involves the intramolecular nucleophilic addition to ketones without the formation of π-allylpalladium species.
- Yu, Xufen,Lu, Xiyan
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p. 6350 - 6355
(2011/10/02)
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- Decarboxylative homocoupling of (hetero)aromatic carboxylic acids
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A variety of hetero(aromatic) carboxylic acids are shown to undergo decarboxylative homocoupling, mediated by a Pd/Ag system. This novel methodology for the synthesis of symmetrical biaryls avoids the use of haloarenes and organometallic compounds as starting materials.
- Cornella, Josep,Lahlali, Hicham,Larrosa, Igor
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supporting information; experimental part
p. 8276 - 8278
(2010/12/19)
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- The first intramolecular Heck-Matsuda reaction and its application in the syntheses of benzofurans and indoles
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In this Letter, we report, for the first time, the development of an efficient method for the intramolecular Heck reaction of arenediazonium salts in the synthesis of benzofuran and indole derivatives. In addition, this methodology allowed the synthesis of a series of dihydrobenzofuran acetic acid derivatives via a domino Heck-Matsuda coupling-carbonylation reaction.
- Siqueira, Fernanda A.,Taylor, Jason G.,Correia, Carlos Roque D.
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supporting information; experimental part
p. 2102 - 2105
(2010/06/14)
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- Silver-catalyzed protodecarboxylation of heteroaromatic carboxylic acids
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[Chemical Equation Presented] A simple and highly efficient protodecarboxylation procedure for a variety of heteroaromatic carboxylic acids catalyzed by Ag2CO3 and AcOH in DMSO is described. This methodology can also perform the selective monoprotodecarboxylation of several aromatic dicarboxylic acids.
- Lu, Pengfel,Sanchez, Carolina,Cornella, Josep,Larrosa, Igor
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supporting information; experimental part
p. 5710 - 5713
(2010/02/28)
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- ANTI-HIV COMPOUNDS
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Thiazole derivatives represented by Formula (I) are disclosed, where R1, R2, R3, A, X, Y, Z, R6 and R7 are disclosed herein. These thiazole derivatives and pharmaceutical compositions comprising these derivatives are useful in the treatment of HIV mediated diseases and conditions.
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Page/Page column 39; 49-50
(2009/08/14)
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- Preparation of 2-, 3-, 4- and 7-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b] furans and their BLT1 and/or BLT2 inhibitory activities
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Several 2-alkylcarbamoyl-1-alkylvinylbenzo[b]furans were designed to find a selective leukotriene B4 (LTB4) receptor antagonist. 2-(2-Alkylcarbamoyl-1-alkylvinyl)benzo[b]furans having a substituent group at the 3-position, 4-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans having a substituent group at the 3-position, and 7-(2-alkylcarbamoyl-1-methylvinyl) benzo[b]furans and 3-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b]furans were prepared and evaluated for LTB4 receptor (BLT1 and BLT 2) inhibitory activities. (E)-3-Amino-4-[2-[2-(3,4-dimethoxyphenyl) ethylcarbamoyl]-1-methylvinyl]benzo[b]furan ((E)-17c) showed potent and selective inhibitory activity for BLT2. On the other hand, (E)-7-(2-diethylcarbamoyl-1-methylvinyl)benzo[b]furan ((E)-27a) showed potent inhibitory activity for both BLT1 and BLT2. This journal is The Royal Society of Chemistry.
- Ando, Kumiko,Kawamura, Yoko,Akai, Yukiko,Kunitomo, Jun-Ichi,Yokomizo, Takehiko,Yamashita, Masayuki,Ohta, Shunsaku,Ohishi, Takahiro,Ohishi, Yoshitaka
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p. 296 - 307
(2008/09/21)
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- Chemoenzymatic preparation of enantiopure l-benzofuranyl- and l-benzo[b]thiophenyl alanines
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Lipase mediated DKR followed by a chemical and an enzymatic hydrolytic step were combined for the synthesis of enantiopure l-benzofuranyl- and l-benzothienyl alanines.
- Podea, Paula Veronica,Tosa, Monica Ioana,Paizs, Csaba,Irimie, Florin Dan
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p. 500 - 511
(2008/09/19)
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- Structure-activity relationships for a novel series of dopamine D2-like receptor ligands based on N-substituted 3-aryl-8-azabicyclo[3.2.1]octan-3-ol
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Discovering dopamine D2-like receptor subtype-selective ligands has been a focus of significant investigation. The D2R-selective antagonist 3-[4-(4-chlorophenyl)-4-hydroxypiperidinyl]methylindole (1, L741,626; K i(D2R/D3R) = 11.2:163 nM) has previously provided a lead template for chemical modification. Herein, analogues have been synthesized where the piperidine was replaced by a tropane ring that reversed the selectivity seen in the parent compound, in human hD2LR- or hD3R-transfected HEK 293 cells (31, Ki(D2R/D3R) = 33.4: 15.5 nM). Further exploration of both N-substituted and aryl ring-substituted analogues resulted in the discovery of several high affinity D2R/D3R ligands with 3-benzofurylmethyl-substituents (e.g., 45, Ki(D2R/D3R) = 1.7:0.34 nM) that induced high affinity not achieved in similarly N-substituted piperidine analogues and significantly (470-fold) improved D3R binding affinity compared to the parent ligand 1. X-ray crystallographic data revealed a distinctive spatial arrangement of pharmacophoric elements in the piperidinol vs tropine analogues, providing clues for the diversity in SAR at the D2 and D3 receptor subtypes.
- Paul, Noel M.,Taylor, Michelle,Kumar, Rakesh,Deschamps, Jeffrey R.,Luedtke, Robert R.,Newman, Amy Hauck
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experimental part
p. 6095 - 6109
(2009/10/01)
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- Synthesis of hetero- and carbocycles by nucleophilic substitution at sp2 carbon
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Vinylic halides having alcohol, sulfonamide, active methine, and thiol moieties as nucleophiles cyclize to hetero- and carbocycles by intramolecular nucleophilic substitution at the sp2 carbon centers. The density functional theory calculations suggest that the cyclization proceeds through SN2-type substitution (the in-plane vinylic nucleophilic substitution, SNVσ), when vinyl halides are substituted with oxygen, nitrogen, and carbon nucleophiles. The substitution with sulfur nucleophiles, in contrast, proceeds through both routes of SNVσ and out-of-plane vinylic nucleophilic substitution (SNVπ).
- Miyauchi, Hironori,Chiba, Shunsuke,Fukamizu, Koji,Ando, Kaori,Narasaka, Koichi
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p. 5940 - 5953
(2008/02/03)
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- Intramolecular photoarylation of alkenes by phenyl cations
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Acetone-sensitized irradiation of various o-chlorophenyl allyl ethers in polar solvents led to either (dihydro)benzofurans or chromanes. The reaction appeared to involve photoheterolysis of the aryl-Cl bond followed by phenyl cation addition onto the tethered double bond either in 5-exo or 6-endo modes. The adduct cation gave the end products by deprotonation: addition of chloride anion or of the solvent, depending on the struc ture: and the conditions used. Preference for the 5-exo mode increased in passing from medium polarity (methylene chloride, ethyl acetate) to high polarity solvents (aqueous acetonitrile, methanol, 2,2,2-trifluoroethanol), for which this was often the exclusive path. The same compounds underwent photohomolysis when irradiated in cyclohexane, and radical cyclization was one of the process occurring. Substitution of a methylene group for the ether oxygen atom made 6-endo cyclization by far the main path in a related o-chlorophenylbutene. Again, the selectivity was higher in polar protic solvents. The results are discussed in terms of in cage ion pair versus free phenyl cation reactions.
- Dichiarante, Valentina,Fagnoni, Maurizio,Mella, Mariella,Albini, Angelo
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p. 3905 - 3915
(2008/02/06)
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- The interaction of heteroaryl-acrylates and alanines with phenylalanine ammonia-lyase from parsley
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Acrylic acids and alanines substituted with heteroaryl groups at the β-position were synthesized and spectroscopically characterized (UV, HRMS, 1H NMR, and 13C NMR spectroscopy). The heteroaryl groups were furanyl, thiophenyl, benzofuranyl, and benzothiophenyl and contained the alanyl side chains either at the 2- or 3-positions. While the former are good substrates for phenylalanine ammonia lyase (PAL), the latter compounds are inhibitors. Exceptions are thiophen-3-yl-alanine, a moderate substrate and furan-3-yl-alanine, which is inert. Possible reasons for these exceptions are discussed. Starting from racemic het eroaryl-2-alanines their D-enantiomers were prepared by using a stereodestructive procedure. From the heteroaryl-2- acrylates, the L-enantiomers of the heteroaryl-2-alanines were prepared at high ammonia concentration. These results can be best explained by a Friedel - Crafts-type electrophilic attack at the aromatic part of the substrates as the initial step of the PAL reaction.
- Paizs, Csaba,Katona, Adrian,Retey, Janos
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p. 2739 - 2744
(2008/02/03)
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- Synthesis of certain benzoheterocyclic com pounds from 2- hydroxyacetophenone via cyclization and ring-closing metathesis
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Syn the sis of some benzoheterocyclic compounds like substituted benzofurans, 4-methyl-2H-chromenes and 3,4-dihydro-2H-benzo[e]oxepin-5-ones from 2-hydroxyacetophenone via base in duced cyclization and ring-closingme tath e sis (RCM) is described.
- Huang, Keng-Shiang,Li, Sie-Rong,Wang, You-Feng,Lin, Yu-Li,Chen, Yung-Hua,Tsai, Tzu-Wei,Yang, Chih-Hui,Wang, Eng-Chi
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p. 159 - 167
(2007/10/03)
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- Halogen-metal exchange/cyclization of iodoketones: A direct synthesis of 3-arylbenzofurans
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The first synthesis of benzofuran 2 was achieved in 17% overall yield in seven steps. The key step was a halogen-metal exchange/cyclization reaction. Several examples of this reaction were reported. Georg Thieme Verlag Stuttgart.
- Kraus, George A.,Schroeder, Jacob D.
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p. 2504 - 2506
(2007/10/03)
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- Theoretical and experimental study on the in-plane SN2-type substitution reaction of haloalkenes with inversion of configuration at the sp2 carbon
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(Equation Presented) The intramolecular in-plane SN2 type reaction of haloalkene E-8a was predicted to be a facile process for the first time by DFT calculations (B3LYP/6-31+G(d),SCRF(dipole, solvent = DMF)) (ΔG = 14.4 kcal/mol). The prediction was confirmed experimentally. When E-8a was treated with NaH in DMF, benzofuran was obtained in 95% yield. On the other hand, Z-8a was recovered quantitatively even after heating at 110 °C.
- Ando, Kaori,Kitamura, Mitsuru,Miura, Kasei,Narasaka, Koichi
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p. 2461 - 2463
(2007/10/03)
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- Novel cyclic amide derivatives
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Novel compounds represented by the following formula (I) that act as a ligand to sigma receptor/binding cite and a medicament comprising the same as an active ingredient: wherein X represents an alkyl group, an aryl group, a heterocyclic group or the like; Q represents a group represented by —CH2—, —CO—, —O—, —CH(OR7)— or the like wherein R7 represents a hydrogen atom, an alkyl group or the like; n represents an integer of from 0 to 5; R1 and R2 each represent a hydrogen atom, an alkyl group or the like; B represents either of the following groups: wherein R3, R4, R5, and R6 each represent a hydrogen atom, a halogen atom, an alkoxyl group or the like; m represents 1 or 2; and the ring of: represents an aromatic heterocyclic ring.
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- Synthesis of fused furans by gas-phase pyrolysis of 2-allyloxyaryl-propenoic esters
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Flash vacuum pyrolysis of 2-allyloxypropenoic esters (e.g. 7) gives benzo[b]furans (e.g. 32) in synthetically useful yields by sequential generation of a phenoxyl radical, cyclisation and ejection of the carboxylic ester function as a free radical leaving group. The method is compatible with a range of substituents on either the benzene ring or the propenoate chain, and is particularly effective for 2-substituted benzo[b]furans. The natural products 5-methoxybenzo[b]furan 1 and angelicin 2 have been synthesised in three and four steps respectively from commercially available starting materials by this route. Related cyclisations to give naphtho[2,1-b]furan 40 were complicated by competitive formation of naphtho[2,1-b]pyran-3-ones (e.g. 41 and 42), but the yield of the required product could be optimised by the choice of the radical precursor. Annelation of a furan ring onto a thlophene is also possible by this method, but lower yields are obtained in such pyrolyses.
- Black, Michael,Cadogan,McNab, Hamish,MacPherson, Andrew D.,Roddam, V. Peter,Smith, Carol,Swenson, Helen R.
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p. 2483 - 2493
(2007/10/03)
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- Electrophilic Reactions of Carbenoids. Synthesis of Fused Heterocyclic Systems via Intramolecular Nucleophilic Substitution of Carbenoids
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Intramolecular nucleophilic substitution of carbenoids with oxygen, nitrogen, and sulfur nucleophiles leading to the synthesis of fused heterocyclic compounds has been studied.For the purpose of this investigation styryl type gem-dihalides 4, 8, 18, 20, 28 containing a nucleophilic substituent in the ortho position of the aromatic ring have been synthesized.Carbenoids have been generated in those systems by the halogen - metal exchange reaction and shown to readily undergo intramolecular nucleophilic substitution by the properly located nucleophilic group (OH, SH, or NH2).As a result a new synthetic route to benzofurans, thianaphthenes, and indoles has been established based on nucleophilic substitution of vinyl halides by an ortho substituent.The dramatic increase of reactivity of vinyl halides upon introduction of lithium has been explained as being due to metal-assisted ionization.
- Topolski, Marek
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p. 5588 - 5594
(2007/10/03)
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- The Mechanism of Titanium Complex-Catalyzed Reduction of Aryl Halides by Sodium Borohydride Is Strongly Solvent Dependent
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The titanium complex-catalyzed reduction of aryl halides by sodium borohydride in dimethylacetamide (DMA) or ethers proceeds by electron transfer from a reduced titanium species, yielding an intermediate aryl radical.
- Liu, Yumin,Schwartz, Jeffrey
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p. 940 - 942
(2007/10/02)
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- Carboxylic Esters as Radical Leaving Groups: A New and Efficient Gas-phase Synthesis of Benzofurans
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Flash vacuum pyrolysis (FVP) of o-allyloxycinnamate esters gives benzofurans in high yield, via cyclisation of a phenoxyl radical and subsequent cleavage of the carboxylic ester function; coumarins are obtained by FVP of the corresponding phenols.
- Black, Michael,Cadogan, J. I. G.,Cartwright, Gary A.,McNab, Hamish,MacPherson, Andrew D.
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p. 959 - 960
(2007/10/02)
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- Benzofuran Derivatives. Part 4. Synthesis of Benzofurans and 2,3,4,5-Tetrahydro-1-benzoxepin-3,5-diones
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By treatment of ethyl 4- or 5-substituted 2-acetylphenoxyacetates 1 with potassium hydroxide in dry dioxane, benzofurans 2-7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 were obtained.The relative yields of benzofurans 2-7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 varied with the types of 4- or 5-substituents.The electron-donating 4-methoxyl group favored the formation of benzoxepins.On the other hand, electron-withdrawing substituents such as the 4-nitro group favored the formation of benzofurans.When esters 1 were treated with sodium amide,2,3-dihydrobenzofurans 2 were obtained exclusively regardless of 4- or 5-substituents.
- Suzuki, Tsuneo,Tanemura, Kiyoshi,Horaguchi, Takaaki,Shimimizu, Takahachi,Sakakibara, Tohru
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p. 423 - 429
(2007/10/02)
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- Cyclodextrin-Promoted Radical Cyclization of o-(2-Propenyloxy)- and o-(2-Propynyloxy)-benzenediazonium Ions
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Radical dediazoniation of o-(2-propenyloxy)- and o-(2-propynyloxy)benzenediazonium ions in the presence of β-cyclodextrin gives selectively dihydrobenzofurans under N2, while hydroxymethylated dihydrobenzofurans and 3-hydroxymethyl-benzofuran under air, respectively.
- Fukunishi, Koushi,Shimode, Mitsuo,Hisamune, Rie,Akita, Makoto,Kuwabara, Masaki,et al.
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p. 337 - 340
(2007/10/02)
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- Cobalt-mediated Radical Reactions in Organic Synthesis. Oxidative Cyclisations of Aryl and Alkyl Halides leading to Functionalised Reduced Heterocycles and Butyrolactones
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Reactions between the CoI species derived from cobalt(III) salen (11) or cobalt(II) salophen (12) and (O-allyl) or (O-but-3-enyl) iodophenols lead to isolatable cobalt complexes, viz. (16) and (27), which can be converted into substituted benzofurans, i.e. (17) and (23), and benzopyrans, i.e. (28) and (34); similarly, interaction between compound (36) and Co1 salen led in one step to 1,3-dimethylindole (37).Radical cyclisation of the acetal (38a) in the presence of Co1 cobaloxime leads to the cis-ring-fused alkyl cobalt complex (42), which can be converted in a preparative manner into lactone (44) following 1,2-elimination and hydrolysis/oxidation, and into lactone (53) following insertion of molecular oxygen , reduction and hydrolysis/oxidation.
- Bhandal, Harcharan,Patel, Vinod F.,Pattenden, Gerald,Russell, Jamie J.
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p. 2691 - 2701
(2007/10/02)
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- Cobalt-Mediated Intermolecular Radical Additions to Carbon-to-Carbon Double Bonds leading to New Functionalised Alkenes
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Alkyl radicals generated by photolytic homolysis of cobalt salophen reagents, e.g. (6) and (15), are shown to add to activated carbon-to-carbon double bonds, i.e. ethyl acrylate, methyl vinyl ketone, acrylonitrile, and styrene, producing preparatively useful yields of new alkene products, viz. (9), (10), (12) and (14) , and (16) .The reactions proceed via radical (Michael) additions, followed by 'dehydrocobaltation' from the presumed organocobalt intermediates (2) (Scheme 4).By use of this chemistry, in combination with the Schrauzer 'hydrocobaltation' reaction of alkenes, a new method for the cross-coupling reactions between two alkenes, leading to new functionalised alkenes, e.g. (24), (25), (26), (27), (28), and (29), is developed .
- Bhandal, Harcharan,Howell, Amy R.,Patel, Vinod F.,Pattenden, Gerald
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p. 2709 - 2714
(2007/10/02)
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- Free Radical Reactions in Synthesis. Homolysis of Alkylcobalt Complexes in the Presence of Radical-Trapping Agents
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Irradiations of the alkylcobalt salophen complexes (14), (21), (22), and (23) in the presence of radical-trapping agents, e.g. molecular oxygen, tetramethylpiperidine oxide, nitrogen monoxide, diphenyl disulphide, diphenyl diselenide, methanesulphonyl chloride, bromotrichloromethane, or iodine, leads to oxygen- , nitrogen- , sulphur/selenium- or halogen- (34) functionalised products.When these radical-trapping methodologies are combined with cobalt-mediated radical cyclisation reactions (Scheme 2) a powerful synthetic procedure, i.e. radical carbon-to-carbon bond formation with simultaneous functionalisation of the product radical centre, becomes available.
- Patel, Vinod F.,Pattenden, Gerald
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p. 2703 - 2708
(2007/10/02)
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- Synthesis of benzofurans, tetrahydrobenzopyrans, and related cyclic ethers via cyclic carbopalladation
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Treatment of a variety of alkenyl ethers (1-8) derived from o-iodophenol, o-iodobenzyl alcohol, and (Z)-3-iodoallyl alcohols with a catalytic amount of Pd(PPh3)4 or Cl2Pd(PPh3)2 in the presence of NEt3 in refluxing CH3CN gives the corresponding cyclic ethers in good yields.
- Negishi, Ei-ichi,Nguyen, Thinh,O'Connor, Brian,Evans, Jeffrey M.,Silveira Jr., Augustine
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