- 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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- Substituent effects of cis-cinnamic acid analogues as plant growh inhibitors
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1-O-cis-Cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals that has been isolated from Spiraea thunbergii Sieb by Hiradate et al. It derives its strong inhibitory activity from cis-cinnamic acid (cis-CA), which is crucial for phytotoxicity. By preparing and assaying a series of cis-CA analogues, it was previously found that the key features of cis-CA for lettuce root growth inhibition are a phenyl ring, cis-configuration of the alkene moiety, and carboxylic acid. On the basis of a structure-activity relationship study, the substituent effects on the aromatic ring of cis-CA were examined by systematic synthesis and the lettuce root growth inhibition assay of a series of cis-CA analogues having substituents on the aromatic ring. While ortho- and para-substituted analogues exhibited low potency in most cases, meta-substitution was not critical for potency, and analogues having a hydrophobic and sterically small substituent were more likely to be potent. Finally, several cis-CA analogues were found to be more potent root growth inhibitors than cis-CA.
- Nishikawa, Keisuke,Fukuda, Hiroshi,Abe, Masato,Nakanishi, Kazunari,Taniguchi, Tomoya,Nomura, Takashi,Yamaguchi, Chihiro,Hiradate, Syuntaro,Fujii, Yoshiharu,Okuda, Katsuhiro,Shindo, Mitsuru
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p. 132 - 147
(2014/01/06)
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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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body text
p. 430 - 439
(2011/07/31)
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- A high hydroarylation activity of K2PtCl4/AgOTf catalyst in the reaction of propiolic acid with unactivated and activated arenes
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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)
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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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p. 529 - 532
(2007/10/03)
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- A CONVENIENT METHOD FOR THE CONVERSION OF trans to cis-CINNAMIC ACIDS
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trans-Cinnamic acids react in sequence with bromine, base, and carbon monoxide to give cis-acids in reasonable yields.
- Galamb, Vilmos,Alper, Howard
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p. 2965 - 2968
(2007/10/02)
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