- Dimethyl sulfoxide mediated elimination reactions in 3-aryl 2,3-dihalopropanoates: Scope and mechanistic insights
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(Chemical Equation Presented) Dimethyl sulfoxide (DMSO) efficiently causes the reductive elimination of 3-aryl 2,3-dibromopropanoates to cinnamates with good yield. With 3-phenyl 2,3-dihalopropanoates, debromination is the major pathway providing 3-phenylacrylate derivatives in high yields, whereas dehydrobromination is a competing pathway with thiophene derivatives. 1H NMR, 81Br NMR, and MS techniques indicated the formation of brominated-DMSO, MeBr, and HBr as byproducts in this transformation with no evidence for the formation of Br2. The dual role of DMSO as a nucleophile and bromine scavenger accounts for the products formed in this reaction.
- Li, Wei,Li, Jianchang,Lin, Melissa,Wacharasindhu, Sumrit,Tabei, Keiko,Mansour, Tarek S.
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- Excited-state Reactions of Triphenylphyrylium Ion with Cinnamate Derivatives: Triplet-mediated Isomerization and Singlet-mediated Dimerization
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Excited-state reactivity of 2,4,6-triphenylpyrylium ion (TPP+) with cinnamates has been studied by fluorescence quenching and laser flash photolysis experiments.Electron-transfer reactions between cinnamates and excited states of TPP+ are reported.The pyryl radical (TPP*) has been observed as an intermediate.In the singlet manifold, dimerization product(s) are reported and in the triplet manifold the trans-cis isomerization product is reported.Selectivity of oxygen in the product formation is observed.This is one of the few systems in which both isomerization and dimerization mechanisms are operating together through a radical cation intermediate.For the first time the dimerization of cinnamate derivatives via a radical cation is reported.
- Ramamurthy, P.,Morlet-Savary, F.,Fouassier, J. P.
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- Unravelling the structural and molecular basis responsible for the anti-biofilm activity of zosteric acid
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The natural compound zosteric acid, or p-(sulfoxy)cinnamic acid (ZA), is proposed as an alternative biocide-free agent suitable for preventive or integrative anti-biofilm approaches. Despite its potential, the lack of information concerning the structural and molecular mechanism of action involved in its anti-biofilm activity has limited efforts to generate more potent anti-biofilm strategies. In this study a 43-member library of small molecules based on ZA scaffold diversity was designed and screened against Escherichia coli to understand the structural requirements necessary for biofilm inhibition at sub-lethal concentrations. Considerations concerning the relationship between structure and anti-biofilm activity revealed that i) the para-sulfoxy ester group is not needed to exploit the anti-biofilm activity of the molecule, it is the cinnamic acid scaffold that is responsible for anti-biofilm performance; ii) the anti-biofilm activity of ZA derivatives depends on the presence of a carboxylate anion and, consequently, on its hydrogen-donating ability; iii) the conjugated aromatic system is instrumental to the anti-biofilm activities of ZA and its analogues. Using a protein pull-down approach, combined with mass spectrometry, the herein-defined active structure of ZA was matrix-immobilized, and was proved to interact with the E. coli NADH:quinone reductase, WrbA, suggesting a possible role of this protein in the biofilm formation process.
- Cattò, Cristina,Dell'Orto, Silvia,Villa, Federica,Villa, Stefania,Gelain, Arianna,Vitali, Alberto,Marzano, Valeria,Baroni, Sara,Forlani, Fabio,Cappitelli, Francesca
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- Organoaluminum-promoted cycloaddition of trialkylsilylketene with aldehydes: A new, stereoselectie approach to cis-2-oxetanones and 2(Z)-alkenoic acids
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The exceptionally bulky methylaluminum bis(4-bromo-2,6-di-tert-butylphenoxide) (MABR) can be successfully utilized as a highly efficient Lewis acid for achieving high stereoselectivity in the cycloaddition of trialkylsilylketene with aldehydes. This method serves as a highly effective route to the synthesis of cis-2-oxetanones from saturated aldehydes, and the synthesis of 2(Z)-alkenoic acids from aromatic and α,β-unsaturated aldehydes.
- Concepcion,Maruoka,Yamamoto
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- Transfer semihydrogenation of alkynes catalyzed by imidazo[1,5-a]pyrid-3-ylidenepd complexes: Positive effects of electronic and steric features on N-heterocyclic carbene ligands
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To investigate the catalytic utility of the imidazo[1,5-a]pyrid-3-ylidene (IPC) ligand, Pd-catalyzed transfer semihydrogenation of alkynes with formic acid as a hydrogen source was conducted. The steric bulkiness of the substituent on N2 affected the configuration of the π-allyl moiety of the precatalyst of IPC-Pd-π-allyl complexes and the robustness of the catalytic process. The catalytic activities of IPC-Pd complexes were clearly higher than those of conventional NHC-Pd complexes.
- Mizuno, Takahiro,Murai, Toshiaki,Shibahara, Fumitoshi,Shibata, Yoshifuru
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- Highly Efficient Pd-Catalyzed Coupling of Arenes with Olefins in the Presence of tert-Butyl Hydroperoxide as Oxidant
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(matrix presented) ArH : benznoid and non-benzenoid. R = H, CH3, Ph. R1 = Ph, CO2Et, COMe, CHO, CO2H, CN. The oxidative coupling of arenes with olefins has been performed efficiently in the presence of catalytic amounts of palladium acetate and benzoquinone (BQ) with tert-butyl hydroperoxide as the oxidant in up to 280 turnover numbers (TON). The catalytic system is especially active for the coupling of heterocycles such as furans and indole with activated olefins. The reaction is highly regio-and stereoselective, giving trans-olefins predominantly.
- Jia, Chengguo,Lu, Wenjun,Kitamura, Tsugio,Fujiwara, Yuzo
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- K2PtCl4/AgOTf as a highly active catalyst for hydroarylation of propiolic acids with arenes
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A new and efficient K2PtCl4/AgOTf catalyst for the hydroarylation of propiolic acid was found. The hydroarylation of propiolic acids gave predominantly (Z)-cinnamic acid derivatives in high yields. The K2PtCl4/AgOTf catalyst showed a high activity to less reactive benzene. Copyright
- Oyamada, Juzo,Kitamura, Tsugio
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- STEREOSELECTIVE SYNTHESIS OF (E)-α,β-UNSATURATED ACIDS FROM C,O,O-TRI(TRIMETHYLSILYL) KETENE ACETAL AND ALDEHYDS
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Aldehydes are converted into (E)-α,β-unsatured carboxylic acids by means of C,O,O-tri(trimethylsilyl) ketene acetal and a catalytic a mount of ZnBr2.
- Bellasoued, Moncef,Gaudemar, Marcel
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- Hypervalent iodine reagents enable chemoselective deboronative/decarboxylative alkenylation by photoredox catalysis
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Chemoselective C(sp3)-C(sp2) coupling reactions under mild reaction conditions are useful for synthesizing alkyl-substituted alkenes having sensitive functional groups. Reported here is a visible-light-induced chemoselective alkenylation through a deboronation/decarboxylation sequence under neutral aqueous reaction conditions at room temperature. This reaction represents the first hypervalent-iodineenabled radical decarboxylative alkenylation reaction, and a novel benziodoxole-vinyl carboxylic acid reaction intermediate was isolated. This C(sp3/sup>)-C(sp2) coupling reaction leads to aryl-and acyl-substituted alkenes containing various sensitive functional groups. The excellent chemoselectivity, stable reactants, and neutral aqueous reaction conditions of the reaction suggest future biomolecule applications.
- Huang, Hanchu,Jia, Kunfang,Chen, Yiyun
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- Photodimerization of trans-Cinnamic Acid in a Bilayer of Dimethyldioctadecylammonium Bromide
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The photochemistry of trans-cinnamic acid (trans-1) was studied in a cast film of dimethyldioctadecylammonium bromide (2), deposited from aqueous dispersions as a crystalline solid by the spontaneous vaporization of water. UV irradiation of the cast film resulted in a highly selective formation of the syn-Head-to-Head dimer, suggesting a parallel orientation of trans-1 within a bilayer film. Analyses with X-ray diffraction, differential scanning calorimetry, and IR spectra revealed the formation of a bilayer structure of 2 in which the molecules of trans-1 are dissolved to interact with 2 of the polar head groups. The photoreactivity of trans-1 in the cast film was found to be dramatically suppressed by heating at 40-60 °C, which is attributed to an improvement in the crystallinity of the bilayer.
- Nakamura, Tomotaka,Takagi, Katsuhiko,Sawaki, Yasuhiko
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- A linear solvation energy relationship study for the reactivity of 2-(4-substituted phenyl)-cyclohe-1-enecarboxylic, 2-(4-substituted phenyl)-benzoic, and 2-(4-substituted phenyl)-acrylic acids with diazodiphenylmethane in various solvents
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The reactivities of 2-(4-substituted phenyl)-cyclohex-1-enecarboxylic acids, 2-(4-substituted phenyl)-benzoic acids, and 2-(4-substituted phenyl)-acrylic acids with diazodiphenylmethane in various solvents were investigated. To explain the kinetic results through solvent effects, the second-order rate constants of the examined acids were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of multiple linear regression analysis, and the solvent effects on the reaction rates were analyzed in terms of initial and transition state contributions. The signs of the equation coefficients support the proposed reaction mechanism. The solvation models for all investigated carboxylic acids are suggested. The quantitative relationship between the molecular structure and the chemical reactivity is discussed, as well as the effect of geometry on the reactivity of the examined molecules.
- Nikolc,Uscumlic,Juranic
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- Pd-Catalyzed decarboxylative cross-coupling reactions of epoxides with α,β-unsaturated carboxylic acids
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A Pd-catalyzed decarboxylative cross-coupling of α,β-unsaturated carboxylic acids with cyclic and acyclic epoxides has been developed. Both β-monosubstituted and β-disubstituted unsaturated carboxylic acids, as well as conjugated diene unsaturated carboxylic acids are suitable reaction substrates. Substituted homoallylic alcohols were obtained in moderate to good yields. The product was obtained as a mixture of diastereomers favoring the anti diastereomer of the cyclic epoxides. This work provides a method for the modification of complex organic molecules containing α,β-unsaturated carboxylic acids.
- Lu, Xiao-Yu,Li, Jin-Song,Wang, Shi-Qun,Zhu, Yu-Jing,Li, Yue-Ming,Yan, Lu-Yu,Li, Jia-Mei,Wang, Jin-Yu,Zhou, Hai-Pin,Ge, Xiu-Tao
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- Reactivity control of a photocatalytic system by changing the light intensity
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We report a novel light-intensity dependent reactivity approach allowing us to selectively switch between triplet energy transfer and electron transfer reactions, or to regulate the redox potential available for challenging reductions. Simply by adjusting the light power density with an inexpensive lens while keeping all other parameters constant, we achieved control over one- and two-photon mechanisms, and successfully exploited our approach for lab-scale photoreactions using three substrate classes with excellent selectivities and good product yields. Specifically, our proof-of-concept study demonstrates that the irradiation intensity can be used to control (i) the available photoredox reactivity for reductive dehalogenations to selectively target either bromo- or chloro-substituted arenes, (ii) the photochemical cis-trans isomerization of olefins versus their photoreduction, and (iii) the competition between hydrogen atom abstraction and radical dimerization processes.
- Kerzig, Christoph,Wenger, Oliver S.
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- Highly selective semihydrogenation of phenylalkynes to (Z)-styrenes using hantzsch ester 1,4-dihydropyridine catalyzed by Pd/C
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Various alkynes have been selectively reduced to the corresponding Z-alkenes catalyzed by Pd/C using Hantzsch ester 1,4-dihydropyridine as the hydrogen source. Georg Thieme Verlag Stuttgart.
- Zhao, Yankai,Liu, Qiang,Li, Jing,Liu, Zhongquan,Zhou, Bo
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- Halodecarboxylation of α,β-acetylenic and α,β-ethylenic acids
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Reaction of bis(collidine)iodine(I) (or bromine (I)) hexafluorophosphate with acetylenic acids led to the corresponding iodo(or bromo)acetylenes in high yields. This halodecarboxylation reaction was also observed with acrylic acids substituted in position 3 by an aryl group or an heteroatom.
- Homsi, Fadi,Rousseau, Gerard
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- Stereospecific electrochemical carboxylation of β-bromostyrene by use of nickel(II) catalyst
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Electrochemical carboxylation of (E)- and (Z)-β-bromostyrenes (1) under an atmospheric pressure of carbon dioxide with a platinum cathode and a magnesium anode in the presence of 20 mol % of NiBr2·bpy proceeded with retention of stereochemistry to give the corresponding (E)- or (Z)-cinnamic acids (2). The stereochemical outcome of nickel(II)-catalyzed electrochemical carboxylations was discussed by comparison with predominant formation of a (Z)-isomer from either (E)- or (Z)-β-bromostyrenes. Copyright
- Kuang, Chunxiang,Yang, Qing,Senboku, Hisanori,Tokuda, Masao
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- Encapsulation of cinnamic acid by cucurbit[7]uril for enhancing photoisomerization
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Cis- or Z-configuration is required for the plant growth-promoting activity of cinnamic acid (CA), whereas the E-form is inactive. Herein, we describe the encapsulation of E-CA by cucurbit[7]uril (CB7) and show that photoisomerization reactions can be more efficiently controlled in aqueous solutions by utilizing this supramolecular approach. Measurements of UV-visible absorption and proton NMR spectra at different pH values confirm that E-CA and its methyl ester, methyl-E-cinnamate (MC), form stronger 1:1 host-guest complexes with CB7 compared to cucurbit[8]uril (CB8) or three cyclodextrins (α-, β-, and γ-CD). Irradiation of (300 nm) UV light to an aqueous solution of the CB7-bound E isomers induces E to Z photoisomerization and the dissociation of the complex. When the same solution is irradiated by (254 nm) UV light, Z to E conformational changes of the unbound Z isomers are observed and are accompanied by restoring the host-guest complex formation.
- Al-Ahdal, Asia,Al-Amodi, Hebah,Bojesomo, Rukayat,Bufaroosha, Muna S.,Moussa, Ziad,Saleh, Na'il
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- Selective homogeneous palladium(0)-catalyzed hydrogenation of alkynes to (Z)-alkenes
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Zero-valent palladium precatalysts containing rigid bidentate bis(arylimino)acenaphthene ligands (shown schematically) facilitate the highly stereoselective homogeneous catalytic hydrogenation of alkynes to (Z)- alkenes. Internal, terminal, aryl-substituted, and cyclic alkynes are suitable substrates, as are some enynes, which are chemoselectively hydrogenated to dienes. E=CO2Me; R1, R2 = 4-OCH3, 4-CH3, 2,6-(CH3)2.
- Van Laren, Martijn W.,Elsevier, Cornelis J.
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- Convenient transfer semihydrogenation methodology for alkynes using a PdII-NHC precatalyst
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A convenient and easy-to-use protocol for the Z-selective transfer semihydrogenation of alkynes was developed, using ammonium formate as the hydrogen source and the easily prepared and commercially available, highly stable complex PdCl(η3-C3H5)(IMes) (1) as the (pre)catalyst. Combined with triphenyl posphine as an additional ligand, this system provides a robust catalytic synthetic method that shows little to no over-reduction or isomerization after full substrate conversion. The system allows the direct use of solvents and reagents, as received from the supplier without drying or purification, thus providing a practical method for semihydrogenation of a broad range of alkynes. The mechanism behind these high and enhanced selectivities was determined through a set of kinetic experiments.
- Drost, Ruben M.,Bouwens, Tessel,Van Leest, Nicolaas P.,De Bruin, Bas,Elsevier, Cornelis J.
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- Templating photodimerization of trans-cinnamic acids with cucurbit[8]uril and γ-cyclodextrin
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(Chemical Equation Presented) Cucurbit[8]uril and γ-cyclodextrin are able to align two olefin molecules in a head-head fashion within their large cavities. Excitation of such templated olefins results in syn head-head cyclobutanes in nearly quantitative yields. The methodology revealed here works with trans-cinnamic acids that do not dimerize either in solution or in the solid state and with the ones that yield only anti head-tail dimer in the solid state.
- Pattabiraman, Mahesh,Natarajan, Arunkumar,Kaanumalle, Lakshmi S.,Ramamurthy
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- Pd Nanoparticles and Aminopolymers Confined in Hollow Silica Spheres as Efficient and Reusable Heterogeneous Catalysts for Semihydrogenation of Alkynes
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A yolk-shell nanostructured composite composed of Pd nanoparticles (NPs) and aminopolymers, poly(ethylenimine) (PEI), confined in hollow silica spheres which act as an efficient and stable heterogeneous catalyst for semihydrogenation of alkynes is reported herein. The yolk-shell nanostructured Pd-PEI-silica composite catalysts (Pd+PEI@HSS), consisting of Pd NPs core ca. 5-9 nm in diameter and a porous silica shell ca. 30-50 nm in shell thickness, are fabricated by a facile one-pot method using linear- or branched-type PEI (Mw = 1,800-2,500) as an organic template. On the basis of comprehensive structural analyses by FE-SEM, TEM, N2 physisorption, IR, TG, and Pd K-edge XAFS, we show that metal Pd NPs and PEI molecules are encapsulated in the hollow silica sphere with a size of ca. 100-160 nm. The Pd+PEI@HSS composite shows an activity at near room temperature in the liquid-phase hydrogenation of diphenylacetylene to selectively produce cis-stilbene with 95% yield, which outperforms those of the previously reported Pd/PEI and Lindlar catalysts. Interestingly, the catalyst encapsulating linear-type PEI provides a markedly high alkene selectivity in the semihydrogenation of phenylacetylene to produce styrene owing to the strong poisoning effect of linear PEI, which is clearly revealed by an isotope study using H2/D2/acetylene (or ethylene) gases. The catalyst synthesized with optimum silica shell thickness can be easily recovered and recycled without any loss of palladium species and PEI and retaining high activities and selectivities over multiple cycles owing to the ability of the protective effect of silica shell, rendering this material an efficient and stable catalyst for semihydrogenation of alkynes.
- Kuwahara, Yasutaka,Kango, Hiroto,Yamashita, Hiromi
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- Dual Nickel/Ruthenium Strategy for Photoinduced Decarboxylative Cross-Coupling of α,β-Unsaturated Carboxylic Acids with Cycloketone Oxime Esters
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Herein, a dual nickel/ruthenium strategy is developed for photoinduced decarboxylative cross-coupling between α,β-unsaturated carboxylic acids and cycloketone oxime esters. The reaction mechanism is distinct from previous photoinduced decarboxylation of α,β-unsaturated carboxylic acids. This reaction might proceed through a nickelacyclopropane intermediate. The C(sp2)-C(sp3) bond constructed by the aforementioned reaction provides an efficient approach to obtaining various cyanoalkyl alkenes, which are synthetically valuable organic skeletons in organic and medicinal chemistry, under mild reaction conditions. The protocol tolerates many critical functional groups and provides a route for the modification of complex organic molecules.
- Gao, Ang,Jiang, Run-Chuang,Liu, Chuang-Chuang,Liu, Qi-Le,Lu, Xiao-Yu,Xia, Ze-Jie
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supporting information
p. 8829 - 8842
(2021/06/30)
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- An Ir3L2complex with anion binding pockets: photocatalyticE-Zisomerizationviamolecular recognition
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A molecular host with photosensitizing centers provides photo-responsive host-guest properties based on its molecular recognition ability. Here, we construct a self-assembled photoactive Ir(iii) cage-shaped complex that contains anion binding pockets on its rim. The anion recognition ability of the complex enables efficient catalysis of the visible-light-inducedE-Zisomerization of an anionic styrene derivative.
- Fujita, Makoto,Koyamada, Kenta,Sunohara, Haruka,Takezawa, Hiroki
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supporting information
p. 9300 - 9302
(2021/09/20)
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- Stereodivergent silver-catalyzed synthesis of pyroglutamic acid esters
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We report here a silver-catalyzed method for the enantio- and diastereodivergent synthesis of chiral pyroglutamic acid esters with multiple stereocenters. This process proceeds through asymmetric conjugate addition of glycine imine esters to a broad range of β-substituted α,β-unsaturated perfluorophenyl esters followed by lactamization. By leveraging catalyst control and stereospecificity of the 1,4-addition process, all four product stereoisomers containing two adjacent stereocenters are accessible with high stereoselectivity.
- Kim, Byungjun,Lee, Sarah Yunmi,Song, Yuna
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supporting information
p. 11052 - 11055
(2021/10/30)
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- Donor-acceptor fluorophores as efficient energy transfer photocatalysts for [2 + 2] photodimerization
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Mild [2 + 2] photodimerization of enone substrates was induced by donor-acceptor fluorophores. Enone substrates were activated efficiently for anti-head to head dimerizations with a high yield (up to 83%) and high selectivity. The adjustable excited state potential also allows donor-acceptor fluorophores to be used for isomerization of the above substrates, confirming the potential of donor-acceptor fluorophores as energy transfer photocatalysts.
- Chen, Feng,Chen, Hao,Liu, Xue-Fen,Luo, Shu-Ping,Ren, Chen-Chao,Wu, Qing-An,Xu, Liang-Xuan,Yu, Xiao-Cong
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supporting information
p. 3707 - 3716
(2020/06/03)
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- Understanding the role played by protic ionic liquids (PILs) and the substituent effect for enhancing the generation of: Z-cinnamic acid derivatives
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Photoisomerization of a series of substituted E-cinnamic acids in MeCN in their acid forms and as their corresponding protic ionic liquids (PILs) with light of 300 nm is studied. The nature, strength, number, and position effects of substituents on the photochemical behavior of E-cinnamic derivatives are investigated. The photosensitization of the reaction in the presence of Michler's ketone is also studied at 366 nm and it demonstrates that the triplet-excited state is involved in the reaction. As the presence of n-butylamine needed to form the PILs significantly increases the photoproduct yields in all cases, the role of the PILs is also discussed. Thus, understanding of these fundamental aspects has allowed us to establish an excellent and practical synthetic protocol for successfully synthesizing Z-cinnamic acids. This journal is
- Rodríguez, Roció B.,Rodríguez, Roció B.,Zapata, Ramiro L.,Salum, Mariá L.,Salum, Mariá L.,Erra-Balsells, Rosa,Erra-Balsells, Rosa
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p. 819 - 830
(2020/07/03)
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- Selective Transfer Semihydrogenation of Alkynes with H2O (D2O) as the H (D) Source over a Pd-P Cathode
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We reported a selective semihydrogenation (deuteration) of numerous terminal and internal alkynes using H2O (D2O) as the H (D) source over a Pd-P alloy cathode at a lower potential. P-doping caused the enhanced specific adsorption of alkynes and the promoted intrinsic activity for producing adsorbed atomic hydrogen (H*ads) from water electrolysis. The semihydrogenation of alkynes could be accomplished at a lower potential with up to 99 % selectivity and 78 % Faraday efficiency of alkene products, outperforming pure Pd and commercial Pd/C. This electrochemical semihydrogenation of alkynes might proceed via a H*ads addition pathway rather than a proton-coupled electron transfer process. The decreased amount of H*ads at a lower potential and the more preferential adsorption of the Pd-P to C≡C π bond than C=C moiety resulted in the excellent alkene selectivity. This method was capable of producing mono-, di-, and tri-deuterated alkenes with up to 99 % deuterium incorporation.
- Liu, Cuibo,Lu, Siyu,Wang, Changhong,Wu, Yongmeng,Zhang, Bin
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supporting information
p. 21170 - 21175
(2020/09/11)
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- Hydrogenation reaction method
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The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
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Paragraph 0034; 0265-0268
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
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- Demethylenation of Cyclopropanes via Photoinduced Guest-to-Host Electron Transfer in an M6L4 Cage
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Unusual demethylenation reactions of cyclopropanes under UV-light irradiation were found within a cavity of a photoactive coordination cage. The reaction proceeded via a guest-to-host electron transfer owing to the highly electron-deficient nature of the cage. The reactions were highly chemoselective and enabled late-stage derivatization of a steroid molecule, which led to a totally new un-natural steroid.
- Cullen, William,Takezawa, Hiroki,Fujita, Makoto
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supporting information
p. 9171 - 9173
(2019/06/24)
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- Palladium catalyzed carbonylations of alkenyl halides with formic acid to get corresponding Α,Β-unsaturated carboxylic acids and esters
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Palladium-catalysed carbonylation reactions have been developed in the presence of formic acid as carbon monoxide source. α,β-Unsaturated carboxylic acids and esters were synthesized by the transformation of alkenyl halides in moderate to good yields. The selection of the base proved to be crucial regarding the reaction outcome. A set of various substrates were proven under optimised reaction conditions. Compared to aliphatic alcohols, phenols showed excellent reactivity as O-nucleophiles.
- Bartal, Brigitta,Mikle, Gábor,Kollár, László,Pongrácz, Péter
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p. 143 - 149
(2019/02/15)
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- Method used for water phase catalysis of acetylenic acid selective hydrogenation reduction preparation of olefine acid
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The invention provides a method used for water phase catalysis of acetylenic acid selective hydrogenation reduction preparation of olefine acid, and belongs to the technical field of chemistry and homogeneous catalystic hydrogenation. According to the method, a water soluble ruthenium complex catalyst is designed and synthesized, and is capable of realizing high-selectivity catalysis of acetylenicacid hydrogenation reduction preparation of olefine acid in water phase. The catalyst preparation method is simple, the selectivity is high, substrate applicability range is wide; taking phenylpropiolic acid reduction as an example, the conversion rate is capable of reaching 100%, cinnamic acid yield is as high as 99%. The catalyst reaction can be carried out in an aqueous solution completely, sothat environment pollution caused by using of organic solvents is avoided.
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Paragraph 0031; 0034
(2019/07/04)
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- The: Trans / cis photoisomerization in hydrogen bonded complexes with stability controlled by substituent effects: 3-(6-aminopyridin-3-yl)acrylate case study
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The association of aminopyridine-based acrylic acid and its salt was studied by NMR titration experiments. The AA (acceptor, acceptor) hydrogen-bonding pattern present in the salt forms a complex readily with a DD (donor, donor) hydrogen-bonding pattern of the substituted ureas even in polar and competitive environment. The double carbon-carbon bond in the acrylic acid derivative is subjected to photoisomerization. This is dependent on the association with substituted urea derivatives. The substituent in ureas influences the trans/cis isomerization kinetics and position of the photostationary state. Two mechanisms that influence the photoisomerization were proposed. To the best of our knowledge, the trans/cis photoisomerization influenced by the substituent in such a hydrogen-bonding pattern has not observed previously. It was shown that interaction with urea derivatives causes lowering of the trans-to-cis photoreaction rates.
- Kwiatkowski, Adam,J?drzejewska, Beata,Józefowicz, Marek,Grela, Izabela,O?mia?owski, Borys
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p. 23698 - 23710
(2018/07/13)
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- Accessing Frustrated Lewis Pair Chemistry through Robust Gold@N-Doped Carbon for Selective Hydrogenation of Alkynes
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Pyrolysis of Au(OAc)3 in the presence of 1,10-phenanthroline over TiO2 furnishes a highly active and selective Au nanoparticle (NP) catalyst embedded in a nitrogen-doped carbon support, Au@N-doped carbon/TiO2 catalyst. Parameters such as pyrolysis temperature, type of support, and nitrogen ligands as well as Au/ligand molar ratios were systematically investigated. Highly selective hydrogenation of numerous structurally diverse alkynes proceeded in moderate to excellent yield under mild conditions. The high selectivity toward the industrially important alkene substrates, functional group tolerance, and the high recyclability makes the catalytic system unique. Both high activity and selectivity are correlated with a frustrated Lewis pairs interface formed by the combination of gold and nitrogen atoms of N-doped carbon that, according to density functional theory calculations, can serve as a basic site to promote the heterolytic activation of H2 under very mild conditions. This "fully heterogeneous" and recyclable gold catalyst makes the selective hydrogenation process environmentally and economically attractive.
- Fiorio, Jhonatan Luiz,Gon?alves, Renato Vitalino,Teixeira-Neto, Erico,Ortu?o, Manuel A.,López, Núria,Rossi, Liane Marcia
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p. 3516 - 3524
(2018/04/14)
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- Highly Selective Semihydrogenation of Alkynes to Alkenes by Using an Unsupported Nanoporous Palladium Catalyst: No Leaching of Palladium into the Reaction Mixture
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We report the highly chemoselective and stereoselective semihydrogenation of alkynes to Z-internal and terminal alkenes by using unsupported nanoporous palladium (PdNPore) as a heterogeneous catalyst under mild reaction conditions (room temperature and 1 atm of H2). The semihydrogenation of various terminal/internal and aromatic/aliphatic alkynes afforded the corresponding alkenes in good chemical yields with high selectivities. PdNPore further showed high chemoselectivity toward terminal alkynes in the presence of internal alkynes, which has not yet been achieved using supported palladium nanoparticle catalysts. H-H heterolysis of H2 on the surface of PdNPore was strongly suggested by deuterium labeling experiments. No Pd leached from PdNPore during the reaction, and the catalyst was easily recovered and reused without a loss of activity.
- Lu, Ye,Feng, Xiujuan,Takale, Balaram S.,Yamamoto, Yoshinori,Zhang, Wei,Bao, Ming
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p. 8296 - 8303
(2017/12/08)
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- One Photocatalyst, n Activation Modes Strategy for Cascade Catalysis: Emulating Coumarin Biosynthesis with (-)-Riboflavin
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Generating molecular complexity using a single catalyst, where the requisite activation modes are sequentially exploited as the reaction proceeds, is an attractive guiding principle in synthesis. This requires that each substrate transposition exposes a catalyst activation mode (AM) to which all preceding or future intermediates are resistant. While this concept is exemplified by MacMillan's beautiful merger of enamine and iminium ion activation, examples in other fields of contemporary catalysis remain elusive. Herein, we extend this tactic to organic photochemistry. By harnessing the two discrete photochemical activation modes of (-)-riboflavin, it is possible to sequentially induce isomerization and cyclization by energy transfer (ET) and single-electron transfer (SET) activation pathways, respectively. This catalytic approach has been utilized to emulate the coumarin biosynthesis pathway, which features a key photochemical E → Z isomerization step. Since the ensuing SET-based cyclization eliminates the need for a prefunctionalized aryl ring, this constitutes a novel disconnection of a pharmaceutically important scaffold.
- Metternich, Jan B.,Gilmour, Ryan
-
supporting information
p. 1040 - 1045
(2016/02/05)
-
- Using non-covalent interactions to direct regioselective 2+2 photocycloaddition within a macrocyclic cavitand
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The relative orientation of guests within ternary inclusion complexes is governed by the host-guest and guest-guest supramolecular interactions. Selectivity in 2+2 photocycloaddition between two alkenes included within a macrocyclic cavitand (γ-cyclodextrin) can be controlled using non-covalent interactions. In this manuscript, we report cavitand-mediated control of regioselectivity between alkyl cinnamates using non-covalent interactions. Using this method, we have shown that regioselectivity can be switched completely from a head-to-head dimer to a head-to-tail dimer. The reactions were also stereoselective in most cases. Stoichiometry experiments were performed to explore relative stabilities of the complexes, which indicate that the ternary complex is more stable than others. Selectivity in the photocycloaddition reaction was also applied retrospectively to deduce intermolecular orientations. Time-dependent conversion study we performed indicates that the observed reactivity of alkenes is representative of the intermolecular orientations in the bulk of the complex medium. Experimental observations and computational studies were used to qualitatively understand the complex structures, and relative magnitudes of the weak interactions. The reactions of complexes were studied in slurry form, and the extent of reaction control suggests a solid-state-like behavior.
- Nguyen, Nga,Clements, Aspen Rae,Pattabiraman, Mahesh
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p. 2433 - 2443
(2016/03/19)
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- Decarboxylative Alkylcarboxylation of α,β-Unsaturated Acids Enabled by Copper-Catalyzed Oxidative Coupling
-
A facile and general method for copper-catalyzed decarboxylative alkylcarboxylation of cinnamic acids with dimethyl 2,2′-azobis(2-methylpropionate) has been developed. The scope and versatility of the reaction was demonstrated, and a broad range of substrates bearing electron-donating and -withdrawing groups on the aromatic rings were all compatible with this reaction to provide desired β,γ-unsaturated esters in moderate to good yields. Moreover, α,β-unsaturated acids with a carbonyl group on the γ-position of acrylic acids also smoothly proceeded to furnish the desired products in good yields.
- Gao, Bao,Xie, Yinjun,Shen, Zhiqiang,Yang, Lei,Huang, Hanmin
-
supporting information
p. 4968 - 4971
(2015/11/03)
-
- Selenium catalyzed oxidation of aldehydes: Green synthesis of carboxylic acids and esters
-
The stoichiometric use of hydrogen peroxide in the presence of a selenium-containing catalyst in water is here reported as a new ecofriendly protocol for the synthesis of variously functionalized carboxylic acids and esters. The method affords the desired products in good to excellent yields under very mild conditions starting directly from commercially available aldehydes. Using benzaldehyde as a prototype the gram scale synthesis of benzoic acid is described, in which the aqueous medium and the catalyst could be recycled at last five times while achieving an 87% overall yield.
- Sancineto, Luca,Tidei, Caterina,Bagnoli, Luana,Marini, Francesca,Lenardo, Eder J.,Santi, Claudio
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p. 10496 - 10510
(2015/08/06)
-
- Facile net cycloaddition approach to optically active 1,5-benzothiazepines
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The 1,5-benzothiazepine moiety is well-known as a versatile pharmacophore, and its derivatives are expected to have antagonism against numerous diseases. Thus, it is desirable to develop a synthetic route that enables facile enantioselective preparation of a wide range of such derivatives. Although the cycloaddition approach could be considered a possible route to these compounds, to date, there has been no precedent of such a protocol. We therefore present the first example of a highly enantioselective net [4 + 3] cycloaddition to afford 1,5-benzothiazepines by utilizing α,β-unsaturated acylammonium intermediates generated by chiral isothiourea catalysts, which undergo two sequential chemoselective nucleophilic attacks by 2-aminothiophenols. This protocol provided cycloadducts in extremely high regioselectivity, with a good-to-excellent stereoselectivity being achieved regardless of the steric and electronic properties of the substrates. This method therefore offers promising synthetic routes for the construction of a library of optically active 1,5-benzothiazepines for assay evaluation.
- Fukata, Yukihiro,Asano, Keisuke,Matsubara, Seijiro
-
supporting information
p. 5320 - 5323
(2015/05/13)
-
- Catalytic Semireduction of Internal Alkynes with All-Metal Aromatic Complexes
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A simple catalytic method involving all-metal aromatic frameworks as precatalysts ensures an efficient route to (Z)-alkenes. Aromatic triangular palladium clusters were used to reduce internal alkynes without any trace of the formation of alkane side products. These trinuclear complexes provide a catalytic system that parallels the activity and selectivity of their best mononuclear peers, and the catalyst likely operates through complementary mechanisms.
- Deyris, Pierre-Alexandre,Ca?eque, Tatiana,Wang, Yanlan,Retailleau, Pascal,Bigi, Franca,Maggi, Raimondo,Maestri, Giovanni,Malacria, Max
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p. 3266 - 3269
(2015/10/28)
-
- Key structural features of cis-cinnamic acid as an allelochemical
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1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C-C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C-C double bond were also investigated.
- Abe, Masato,Nishikawa, Keisuke,Okuda, Katsuhiro,Shindo, Mitsuru,Fukuda, Hiroshi,Nakanishi, Kazunari,Tazawa, Yuta,Taniguchi, Tomoya,Park, So-Young,Hiradate, Syuntaro,Fujii, Yoshiharu
-
p. 56 - 67,12
(2012/12/12)
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- Dinuclear zinc catalyzed asymmetric spirannulation reaction: An umpolung strategy for formation of α-alkylated-α-hydroxyoxindoles
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A highly diastereo- and enantioselective formal [3 + 2] cycloaddition of α,β-unsaturated esters and 3-hydroxyoxindoles catalyzed by a dinuclear zinc-ProPhenol complex is reported. The stereoselective Michael additions of 3-hydroxyoxindoles and the subsequent transesterifications afford spirocyclic δ-lactones.
- Trost, Barry M.,Hirano, Keiichi
-
supporting information; experimental part
p. 2446 - 2449
(2012/07/27)
-
- N-heterocyclic carbene-catalyzed (4 + 2) cycloaddition/decarboxylation of silyl dienol ethers with α,β-unsaturated acid fluorides
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Herein we report the first all-carbon N-heterocyclic carbene-catalyzed (4 + 2) cycloaddition. The reaction proceeds with α,β-unsaturated acid fluorides and silyl dienol ethers and produces 1,3-cyclohexadienes with complete diastereocontrol (dr >20:1) while demonstrating a new type of reaction cascade exploiting α,β-unsaturated acyl azoliums.
- Ryan, Sarah J.,Candish, Lisa,Lupton, David W.
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supporting information; scheme or table
p. 4694 - 4697
(2011/05/28)
-
- Probes for narcotic receptor mediated phenomena. 41. Unusual inverse μ-agonists and potent μ-opioid antagonists by modification of the N-substituent in enantiomeric 5-(3-hydroxyphenyl)morphans
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Conformational restraint in the N-substituent of enantiomeric 5-(3-hydroxyphenyl)morphans was conferred by the addition of a cyclopropane ring or a double bond. All of the possible enantiomers and isomers of the N-substituted compounds were synthesized. Opioid receptor binding assays indicated that some of them had about 20-fold higher μ-affinity than the compound with an N-phenylpropyl substituent (Ki = 2-450 nM for the examined compounds with various N-substituents). Most of the compounds acted unusually as inverse agonists in the [35S]GTP-γ-S functional binding assay using nondependent cells that stably express the cloned human μ-opioid receptor. Two of the N-substituted compounds with a cyclopropane ring were very potent μ-opioid antagonists ((+)-29, Ke = 0.17 and (-)-30, Ke =0.3) in the [35S]GTP-γ-S functional binding assay. By comparison of the geometry-optimized structures of the newly synthesized compounds, an attempt was made to rationalize their μ-opioid receptor affinity in terms of the spatial position of N-substituents. This article not subject to U.S. Copyright. Published 2011 by the American Chemical Society.
- Cheng, Kejun,Lee, Yong Sok,Rothman, Richard B.,Dersch, Christina M.,Bittman, Ross W.,Jacobson, Arthur E.,Rice, Kenner C.
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p. 957 - 969
(2011/04/24)
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- Catalytic hydroarylation of alkynes with arenes in the presence of FeCl3 and AgOTf
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Hydroarylation of propiolic acids with various arenes in TFA proceeded efficiently in the presence of FeCl3/AgOTf catalyst system. In the case of electron-rich arenes, the iron-catalyzed hydroarylation gave cinnamic acids in moderate to high yields. The hydroarylation of phenylacetylene was observed but the catalyst was not effective under the same conditions.
- Hashimoto, Takuya,Kutubi, Md. Shahajahan,Izumi, Takayuki,Rahman, Ataur,Kitamura, Tsugio
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experimental part
p. 99 - 105
(2011/02/16)
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- Application of PET deprotection for orthogonal photocontrol of aqueous solution viscosity
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Photorelease and photoisomerization of trans-cinnamic acid in aqueous CTAB solutions induces a bulk solution viscosity increase and decrease, respectively, triggered by orthogonal irradiation wavelengths.
- Borak, J. Brian,Lee, Hee-Young,Raghavan, Srinivasa R.,Falvey, Daniel E.
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supporting information; experimental part
p. 8983 - 8985
(2011/02/16)
-
- Oxindole synthesis by palladium-catalysed aromatic C-H alkenylation
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A strategy involving palladium-catalysed aromatic C-H functionalisation/ intramolecular alkenylation provides a convenient and direct synthesis of 3-alkylideneoxindoles. In the presence of 5 mol% of PdCl2MeCN 2 and AgOCOCF3, a wide variety of N-cinnamoylanilines gave 3-alkylideneoxindoles in moderate to good yield. The Royal Society of Chemistry.
- Ueda, Satoshi,Okada, Takahiro,Nagasawa, Hideko
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supporting information; experimental part
p. 2462 - 2464
(2010/08/13)
-
- Photoisomerization of ionic liquid ammonium cinnamates: One-pot synthesis-isolation of Z-cinnamic acids
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Photoisomerization presents the only direct method for contra-thermodynamic E-Z isomerization of olefins. Synthetic applications of this method have been limited by its reversible nature, which leads to a photostationary-state mixture of both isomers. For the first time, a highly efficient one-pot preparation-isolation of solid ionic liquid Z-cinnamic acids by photoisomerization in acetonitrile solution of ionic liquid E-cinnamic acids is described.
- Salum, Maria L.,Robles, Cecilia J.,Erra-Balsells, Rosa
-
supporting information; experimental part
p. 4808 - 4811
(2011/01/03)
-
- Iron(III)-catalyzed hydroarylation of propiolic acid with activated arenes
-
FeCl3/AgOTf-catalyzed hydroarylation of propiolic acid with electron-rich arenes such as mesitylene, tetramethylbenzene, and pentamethylbenzene in trifluoroacetic acid proceeded to give 3-arylpropenoic acids in moderate to high yields. The same reactions with anisole and 1,4-dimethoxybenzene afforded double hydroarylation products, 3,3-diarylpropionic acids.
- Hashimoto, Takuya,Izumi, Takayuki,Kutubi, Md. Shahajahan,Kitamura, Tsugio
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scheme or table
p. 761 - 763
(2010/04/05)
-
- Urease inhibitiory flavone glucosides from Marrubium anisodon
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Compounds 1-3, new flavonoid glucosides have been isolated from the ethyl acetate soluble fractions of Marrubium anisodon, along with apigenin 4′-0-β-D-glucopyranoside 4, kaempferol 3-0-β-D-glucopyranoside 5 and β-sitosterol 3-0-β-D-glucopyranoside 6, respectively. Their structures were assigned from 1H- and 13C-NMR spectra, DEPT and by COSY, HMQC, NOESY and HMBC experiments. Compounds 1-5 showed significant inhibitory activity against the enzyme urease.
- Hussain,Perveen,Malik,Afza,Iqbal,Tareen
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experimental part
p. 1329 - 1335
(2010/08/05)
-
- A high hydroarylation activity of K2PtCl4/AgOTf catalyst in the reaction of propiolic acid with unactivated and activated arenes
-
A mixed catalyst K2PtCl4/AgOTf showed the highest activity for hydroarylation of propiolic acid, among palladium and platinum catalysts. This catalyst was effective for hydroarylation with less reactive benzene to give cis-cinnamic acid in good yield. The hydroarylation with toluene gave a higher yield of hydroarylation products than that with benzene and resulted in ortho/para orientation with an almost statistical ratio, suggesting that the result is very close to that of the Friedel-Crafts alkylation with methyl bromide or p-nitrobenzyl chloride. Hydroarylation of propiolic acid with other electron-rich arenes proceeded efficiently in the presence of the K2PtCl4/AgOTf catalyst in trifluoroacetic acid forming cis-cinnamic acids in good to high yields. This method was also applied to hydroarylation of ethyl propiolate.
- Oyamada, Juzo,Hashimoto, Takuya,Kitamura, Tsugio
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experimental part
p. 3626 - 3632
(2010/01/18)
-
- SULFONYL PYRROLIDINES, METHOD FOR PRODUCING THE SAME AND THEIR USE AS DRUGS
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The invention relates to substituted sulfonylpyrrolidines of the formula I and to the physiologically tolerated salts thereof, as well as to their use as medicaments.
- -
-
Page/Page column 67-68
(2008/06/13)
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- Partial hydrogenation of alkynes to cis-olefins by using a novel Pd 0-polyethyleneimine catalyst
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The creation and application of a new Pd0-polyethyleneimine complex catalyst (Pd0-PEI) was investigated. The 55 Pd 0-PEI catalyst was prepared by introduction of Pd(OAc)2 directly in the MeOH solution of deaerated PEI under Ar atmosphere. Reactions were carried out using 10 weight % versus substrate of 5% Pd0-PEI in 2mL solvent under H2 atmosphere at room temperature. The generality of the process was shown by disubstituting alkynes. Even for the substrate bearing a conjugated ketone on the alkyne, the serious over-reduction was not observed while significant cistrans isomerization of methyl styryl ketone accompanied the partial hydrogenation on the basis of keto-enol tautomerism. Pd0-PEI catalyst is also applicable to the partial hydrogenation of monosubstituted alkynes to monosubstituted olefins.
- Sajiki, Hironao,Mori, Shigeki,Ohkubo, Tomoyuki,Ikawa, Takashi,Kume, Akira,Maegawa, Tomohiro,Monguchi, Yasunari
-
supporting information; experimental part
p. 5109 - 5111
(2009/05/07)
-
- Mild zinc-promoted Horner-Wadsworth-Emmons reactions of diprotic phosphonate reagents
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We report the development of a mild protocol for the Horner-Wadsworth- Emmons reaction of diprotic phosphonates that makes use of a zinc triflate promoter in the presence of mild ter-tiary amine bases to produce α,β-unsaturated carboxylic acids and amides. Georg Thieme Verlag Stuttgart.
- Schauer, Douglas J.,Helquist, Paul
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p. 3654 - 3660
(2008/03/13)
-
- N-azabicyclo-amide derivatives
-
Compounds of the general formula I wherein A represents: D represents oxygen, or sulfur and R1, R2and R3are as defined in the specification, enantiomers thereof, pharmaceutically-acceptable salts thereof, processes for preparing them, pharmaceutical compositions containing them and their use in therapy, especially in the treatment or prophylaxis of psychotic disorders and intellectual impairment disorders.
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-
Page column 21
(2010/02/05)
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- Unusual fragmentation of fulvene endoperoxides with phenyliodosyl bis(trifluoroacetate) (PIFA)
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Reaction of unsaturated fulvene endoperoxides with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate gave saturated fulvene endoperoxides containing the 1,2-dihydropyridazine ring. Treatment of dihydropyridazine endoperoxides with water followed by phenyliodosyl bis(trifluoroacetate) oxidation provided acrylic acid derivatives and dimethyl pyridazine-3,6-dicarboxylate.
- Oezer, Galip,Saracoglu, Nurullah,Balci, Metin
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p. 529 - 533
(2007/10/03)
-