- Discriminating non-ylidic carbon-sulfur bond cleavages of sulfonium ylides for alkylation and arylation reactions
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A sulfonium ylide participated alkylation and arylation under transition-metal free conditions is described. The disparate reaction pattern allowed the separate activation of non-ylidic S-alkyl and S-aryl bond. Under acidic conditions, sulfonium ylides serve as alkyl cation precursors which facilitate the alkylations. While under alkaline conditions, cleavage of non-ylidic S-aryl bond produces O-arylated compounds efficiently. The robustness of the protocols were established by the excellent compatibility of wide variety of substrates including carbohydrates.
- Fang, Jing,Li, Ting,Ma, Xiang,Sun, Jiuchang,Cai, Lei,Chen, Qi,Liao, Zhiwen,Meng, Lingkui,Zeng, Jing,Wan, Qian
-
supporting information
p. 288 - 292
(2021/07/25)
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- Hypervalent iodine(iii) induced oxidative olefination of benzylamines using Wittig reagents
-
We have developed hypervalent iodine(iii) induced oxidative olefination of primary and secondary benzylamines using 2C-Wittig reagents, which provides easy access to α,β-unsaturated esters. Mild reaction conditions, good to excellent yields with high (E) selectivity, and a broad substrate scope are the key features of this reaction. We have successfully carried out the gram-scale synthesis of α,β-unsaturated esters.
- Ramavath, Vijayalakshmi,Rupanawar, Bapurao D.,More, Satish G.,Bansode, Ajay H.,Suryavanshi, Gurunath
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p. 8806 - 8813
(2021/05/26)
-
- Photoinduced Oxidative Alkoxycarbonylation of Alkenes with Alkyl Formates
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A photoinduced oxidative alkoxycarbonylation of alkenes initiated by intermolecular addition of alkoxycarbonyl radicals has been demonstrated. Employing alkyl formates as alkoxycarbonyl radical sources, a range of α,β-unsaturated esters were obtained with good regioselectivity and E selectivity under ambient conditions.
- Tang, Wan-Ying,Chen, Ling,Zheng, Ming,Zhan, Le-Wu,Hou, Jing,Li, Bin-Dong
-
supporting information
p. 3939 - 3943
(2021/05/26)
-
- Trisubstituted Highly Activated Benzo[ d]thiazol-2-yl-sulfone-Containing Olefins as Building Blocks in Organic Synthesis
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In this paper, we report the formation of highly electrophilic 1,1-deactivated olefins, their use as novel synthetic building blocks, and their transformation to structurally diverse molecular scaffolds. Synthesis of 1,1-deactivated olefins substituted with a BT-sulfonyl group and a carbonyl or nitrile, respectively, consists of unusual Ti(OPri)4-mediated Knoevenagel-type condensation and proceed in good to excellent yields. Generated olefins can be further transformed in a highly stereoselective manner and in good yields to various polyfunctionalized heterocycles and acyclic molecular scaffolds. Overall, the obtained structures are accessed in two to four steps starting from the (mostly) commercially available aldehydes. In addition, the presence of the BT-sulfonyl group in prepared structures allows for further chemoselective functionalization/post-synthetic transformations to provide structurally diverse final compounds.
- Baar, Lubomír V.,J.-Y. D. Bon, David,Ková?, Ond?ej,Pospí?il, Ji?í,Roiser, Lukas,Waser, Mario,Zále?ák, Franti?ek
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p. 7192 - 7206
(2020/06/27)
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- Preparation method of cinnamate in eutectic solvent (by machine translation)
-
The invention discloses a method for preparing cinnamate from a eutectic solvent. A mol of choline chloride, B mol of methanesulfonic acid (p-toluenesulfonic acid) was added to a dry three-port flask, stirred at room temperature for eutectic solvent, C mol of cinnamic acid, D mol of alcohol, 50 °C for reaction, TLC was monitored until reaction was complete. After the completion of the reaction, the reaction liquid is poured into water, extracted with dichloromethane, the organic phase is distilled off to obtain a cinnamate, and the aqueous phase is recovered to obtain a eutectic solvent. The method does not need an organic solvent, and is simple to operate, high in yield, high in product purity, short in reaction time, simple in post-treatment, environmentally friendly and low in cost. (by machine translation)
- -
-
Paragraph 0037-0039
(2020/07/02)
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- Coumaric acid analogues inhibit growth and melanin biosynthesis in Cryptococcus neoformans and potentialize amphotericin B antifungal activity
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Fungal infections are on the rise, since the imunocompromised population is increasing due to AIDS/HIV, organ transplant and chemotherapy. Many environmental and pathogenic fungi are able to accomplish melanin biosynthesis as a virulence factor to promote host invasion. Melanized cells are more resistant to radiation, oxidative and osmotic stresses; also melanin confers an advantage in vivo, since melanized cells are more resistant to phagocytic engulfment and oxidative stress caused by the host defense cells and by some antifungal drugs, such as fluconazole (FCZ) and amphotericin B (AmB). Brown, red or black melanin pigments can be produced by the polyketide pathway (DHN-melanin) or from dihydroxyphenols, such as L-DOPA (L-3,4-dihydroxyphenylalanine) and L-tyrosine by polyphenoloxidases. Among several pathogenic fungi, Cryptococcus neoformans is a melanized yeast that causes pneumonia and meningoencephalitis in immunocompromised patients. The knockout of the laccase genes or other interruptions on melanin biosynthetic pathway generates cryptococcal strains with attenuated virulence in an animal model. In this study 16 analogues of coumaric and cinnamic acid were evaluated as possible tyrosinase inhibitors. We have identified some valuable inhibitors of C. neoformans growth and melanin biosynthesis disruption agents. The results showed that coumaric acid derivatives (1a-c), the ketones (3a-b) and 2-allylphenol (7c) are significant inhibitors of tyrosinase and melanization of the fungus. Two analogues (1b and 3b) were selected as promising antimelanogenic agents to be combined with AmB, showing to promote 16-fold reduction in the AmB fungicidal concentration with no appreciable cytotoxicity to mammalian cells. The data suggest that inhibition of the melanin biosynthesis by these compounds may increase the susceptibility of the cells to the oxidative stress generated by AmB. In summary, our data show that C. neoformans can be a suitable model system to test novel inhibitors that target melanin biosynthesis, and novel compounds for adjunct therapy against C. neoformans were identified.
- Melhem, Marcia S. C.,Oliveira, Lidiane,Pascon, Renata C.,Vallim, Marcelo A.,Varela, Marina Themoteo,dos Santos, Alexandre Paes,Corrêa, Isabela Teresa Santos,Fernandes, Jo?o Paulo S.,Ferrarini, Márcio,Tempone, André Gustavo
-
-
- Coumaric acid derivatives as tyrosinase inhibitors: Efficacy studies through in silico, in vitro and ex vivo approaches
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p-Coumaric acid is a known inhibitor of tyrosinase, an enzyme involved in the initial steps of the melanin synthesis in human and other species. However, its low lipophilicity impairs its penetration through skin and efficacy as antimelanogenic agent indeed. Accordingly, this paper reports the assessment of several coumaric acid derivatives as tyrosinase inhibitors and antimelanogenic agents in in vitro, in silico and ex vivo assays. The compounds were designed with modifications in the aromatic and acid moieties of p-coumaric acid, being the coumarate esters the most promising derivatives. The compounds showed higher tyrosinase inhibitory activity (pIC50 3.7–4.2) than the parent acid, being compounds 1d, 1e and 1f the most potent inhibitors. Docking analysis showed that these esters are competitive inhibitors per se, and act independently of a redox mechanism as suggested by DPPH assays. Moreover, the esters showed efficacy in reducing the melanin deposition in human skin fragments at 0.1% concentration, especially compound 1e. In summary, there is an important equilibria between tyrosinase affinity and lipophilicity that must be considered to get effective antimelanogenic agents with adequate permeability in the skin.
- Fernandes, Jo?o Paulo S.,Ferrarini, Márcio,Mercaldi, Vitória Gallo,Nazato, Lucas Idacir Sbrugnera,Padovani, Giovana,Sufi, Bianca da Silva,Varela, Marina Themoteo
-
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- Carbocation Lewis Acid TrBF4-Catalyzed 1,2-Hydride Migration: Approaches to (Z)-α,β-Unsaturated Esters and α-Branched β-Ketocarbonyls
-
Carbocation Lewis acid TrBF4-catalyzed 1,2-hydride migration of α-alkyldiazoacetates themselves or in situ-generated cross-coupling adducts of aldehydes and α-alkyldiazoacetates has been developed, affording (Z)-α,β-unsaturated esters and α-branched β-ketocarbonyls, respectively, in good yields and with high regioselectivities.
- Duan, Depeng,Liu, Yongjun,Lv, Jian,Shang, Wansong
-
supporting information
(2019/10/08)
-
- Novel multi-dentate phosphines for Pd-catalyzed alkoxycarbonylation of alkynes promoted by H2O additive
-
A series of novel multi (bi-/tri-/tetra-)-dentate phosphines with good robustness against water and oxygen were synthesized and fully characterized. It was found that the developed ionic tri-dentate phosphine (L2′) enabled Pd-catalyzed alkoxycarbonylation of alkynes most efficiently while H2O was used as an additive instead of acid. As for L2′, its unique steric configuration with two types of potential P-P chelation modes (P?P distance of 4.31 ? and 4.36 ? respectively) to Pd-centre rendered the corresponding Pd-catalyst high activity and good stability for alkoxycarbonylation of alkynes. The in situ FT-IR analysis also verified that the formation and stability of Pd–H active species were greatly facilitated with the presence of L2′ as well as H2O additive. In addition, as an ionic phosphine, L2′ based PdCl2(MeCN)2 system immobilized in RTIL of [Bmim]NTf2 could be recycled for 7 runs without obvious activity loss or metal leaching.
- Yang, Da,Liu, Lei,Wang, Dong-Liang,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
-
p. 236 - 244
(2019/02/19)
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- Enantioselective [2+2] Cycloadditions of Cinnamate Esters: Generalizing Lewis Acid Catalysis of Triplet Energy Transfer
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We report the enantioselective [2+2] cycloaddition of simple cinnamate esters, the products of which are useful synthons for the controlled assembly of cyclobutane natural products. This method utilizes a cocatalytic system in which a chiral Lewis acid accelerates the transfer of triplet energy from an excited-state Ir(III) photocatalyst to the cinnamate ester. Computational evidence indicates that the principal role of the Lewis acid cocatalyst is to lower the absolute energies of the substrate frontier molecular orbitals, leading to greater electronic coupling between the sensitizer and substrate and increasing the rate of the energy transfer event. These results suggest Lewis acids can have multiple beneficial effects on triplet sensitization reactions, impacting both the thermodynamic driving force and kinetics of Dexter energy transfer.
- Daub, Mary Elisabeth,Jung, Hoimin,Lee, Byung Joo,Won, Joonghee,Baik, Mu-Hyun,Yoon, Tehshik P.
-
supporting information
p. 9543 - 9547
(2019/06/24)
-
- Trimethylphosphine-Promoted Alcoholysis of α,β-Unsaturated Imides and α,β-Unsaturated Esters
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α,β-Unsaturated imides and α,β-unsaturated esters were found to undergo alcoholysis in the presence of trimethylphosphine. The reaction is initiated by nucleophilic addition of trimethylphosphine to the double bond of the α,β-unsaturated carbonyl compound. Saturated imides also undergo the alcoholysis in the presence of the corresponding α,β-unsaturated imide.
- Sato, Haruka,Hosokawa, Seijiro
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p. 1343 - 1349
(2018/01/27)
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- Chalcone and cinnamate synthesis via one-pot enol silane formation-Mukaiyama aldol reactions of ketones and acetate esters
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Aryl alkyl ketones, acetate esters, and acetamides undergo facile one-pot enol silane formation, Mukaiyama aldol addition, and dehydrosilyloxylation in the presence of an amine base and excess trimethylsilyl trifluoromethanesulfonate. The chalcone and cinnamate products are generally recovered in high yield. The relative stoichiometry of the trimethylsilyl trifluoromethanesulfonate and amine base reagents determines whether the reaction yields the β-silyloxy carbonyl product or the α,β-unsaturated carbonyl.
- Downey, C. Wade,Glist, Hadleigh M.,Takashima, Anna,Bottum, Samuel R.,Dixon, Grant J.
-
supporting information
p. 3080 - 3083
(2018/07/06)
-
- Bioactivity and structure–activity relationship of cinnamic acid derivatives and its heteroaromatic ring analogues as potential high-efficient acaricides against Psoroptes cuniculi
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A series of cinnamic acid derivatives and its heteroaromatic ring analogues were synthesized and evaluated for acaricidal activity in vitro against Psoroptes cuniculi, a mange mite. Among them, eight compounds showed the higher activity with median lethal concentrations (LC50) of 0.36–1.07 mM (60.4–192.1 μg/mL) and great potential for the development of novel acaricidal agent. Compound 40 showed both the lowest LC50 value of 0.36 mM (60.4 μg/mL) and the smallest median lethal time (LT50) of 2.6 h at 4.5 mM, comparable with ivermectin [LC50 = 0.28 mM (247.4 μg/mL), LT50 = 8.9 h], an acaricidal drug standard. SAR analysis showed that the carbonyl group is crucial for the activity. The type and chain length of the alkoxy in the ester moiety and the steric hindrance near the ester group significantly influence the activity. The esters were more active than the corresponding thiol esters, amides, ketones or acids. Replacement of the phenyl group of cinnamic esters with α-pyridyl or α-furanyl significantly increase the activity. Thus, a series of cinnamic esters and its heteroaromatic ring analogues with excellent acaricidal activity emerged.
- Chen, Dong-Dong,Zhang, Bing-Yu,Liu, Xiu-Xiu,Li, Xing-Qiang,Yang, Xin-Juan,Zhou, Le
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p. 1149 - 1153
(2018/03/05)
-
- Synthesis of (E)-cinnamyl ester derivatives via a greener Steglich esterification
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Cinnamic acid derivatives are known antifungal, antimicrobial, antioxidant, and anticancer compounds. We have developed a facile and mild methodology for the synthesis of (E)-cinnamate derivatives using a modified Steglich esterification of (E)-cinnamic acid. Using acetonitrile as the solvent, rather than the typical chlorinated solvent, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as the coupling agent enables ester conversion in 45 min with mild heating (40–45 °C) and an average yield of 70% without need for further purification. These conditions were used to couple (E)-cinnamic acid with 1° and 2° aliphatic alcohols, benzylic and allylic alcohols, and phenols. This work demonstrates a facile and greener methodology for Steglich esterification reactions.
- Lutjen, Andrew B.,Quirk, Mackenzie A.,Barbera, Allycia M.,Kolonko, Erin M.
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p. 5291 - 5298
(2018/05/04)
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- A highly efficient Pd/CuI-catalyzed oxidative alkoxycarbonylation of α-olefins to unsaturated esters
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A new protocol for the alkoxycarbonylation of α-olefins to the corresponding unsaturated esters has been developed. Differently substituted styrenes were selectively converted to cinnamate derivatives, via C[sbnd]H bond functionalization. Various palladium sources, including heterogeneous ones, in combination with CuI exhibited a high catalytic efficiency using oxygen as the most cheap oxidant. Monocarbonylated products were obtained in good yields and high chemoselectivity working with a low CO pressure (2 atm) and an excess of air (35 atm) avoiding in this way explosion risks. Commercial cinnamate derivatives were prepared in good to excellent yields by this very simple one-pot procedure.
- Maffei, Mathias,Giacoia, Gabriele,Mancuso, Raffaella,Gabriele, Bartolo,Motti, Elena,Costa, Mirco,Della Ca’, Nicola
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p. 435 - 443
(2016/12/16)
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- Regioselective hydrocarbonylation of phenylacetylene to α,β-unsaturated esters and thioesters with Fe(CO)5and Mo(CO)6
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A highly regioselective hydrocarbonylation of phenylacetylene with thiols and alcohols was developed using metal carbonyls/diazabicyclo[2.2.2]octane (DABCO) system at 100?°C in DMF. The use of Mo(CO)6and thiols in the presence of DABCO was applied as an efficient Pd-free method for hydrothiocarbonylation of phenylacetylene into trans-α,β-cinamyl thioesters in excellent yields (88–98%). Similar reaction using Fe(CO)5/ROH/DABCO system resulted into high yield synthesis of trans-α,β-cinamyl esters (87–98%). These reactions were conducted under mild reaction conditions without the need to use gaseous CO or any phosphine ligand and palladium catalyst.
- Iranpoor, Nasser,Firouzabadi, Habib,Riazi, Asma,Pedrood, Keyvan
-
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- 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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- 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
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p. 5320 - 5323
(2015/05/13)
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- TiCl4-mediated olefination of aldehydes with acetic acid and alkyl acetates: A stereoselective approach to (E)-α,β-unsaturated carboxylic acids and esters
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A new method has been developed for the preparation of α,β- unsaturated carboxylic acids and corresponding esters with (E)-stereoselectivity via the TiCl4-mediated olefination of aldehydes. The method, which uses readily available acetic acid or its alkyl esters as active methylene partners, is more flexible and complementary to conventional routes in the preparation of (E)-cinnamic acid derivatives.
- Augustine, John Kallikat,Boodappa, Chandrakantha,Venkatachaliah, Srinivasa,Mariappan, Ayyampillai
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p. 3503 - 3506
(2014/06/10)
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- Synthesis and SAR investigation of natural phenylpropene-derived methoxylated cinnamaldehydes and their novel Schiff bases as potent antimicrobial and antioxidant agents
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A series of cinnamyl compounds were synthesized from abundantly available methoxylated phenylpropenes and evaluated for their antimicrobial activity by the broth microdilution method against fourteen opportunistic bacterial and fungal human pathogens. Structure-activity relationship studies indicated that methylenedioxy cinnamaldehyde exhibited promising broad-spectrum activity against the tested microorganisms and hence was used as a lead structure to synthesize novel Schiff bases/heterocyclic compounds (23-33) under microwave irradiation. Out of these, thiazole-based Schiff bases have shown promising antibacterial activity against B. subtilis (26; MIC 0.12 mM), M. luteus (27; MIC 0.20 mM), and S. aureus (27; MIC 0.20 mM). Also, the compounds 23-33 were investigated for in vitro antioxidant activity using DPPH? assay where compound 28 showed a maximum of 80.71 % inhibition.
- Sharma, Upendra K.,Sood, Swati,Sharma, Nandini,Rahi, Praveen,Kumar, Rakesh,Sinha, Arun K.,Gulati, Arvind
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p. 5129 - 5140
(2013/12/04)
-
- Asymmetric synthesis of novel N-(1-phenyl-2,3-dihydroxypropyl) arachidonylamides and evaluation of their anti-inflammatory activity
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Aims: To design and synthesize novel N-(1-phenyl-2,3-dihydroxypropyl) arachidonylamides and evaluate their analgesic and anti-inflammatory potential. Main methods: The murine macrophage cell line RAW 264.7 has been widely used as a model for inflammatory responses in vitro. Our model consists of cultured monolayers of RAW 264.7 cells in which media concentrations of 15-deoxy-Δ13,14-PGJ2 (PGJ) are measured by ELISA following LPS (10 ng/ml) stimulation and treatment with 0.1, 0.3, 1.0, 3.0 and 10 μM concentrations of the compounds. Key findings: Our data indicate that several of our compounds have the capacity to increase production of PGJ and may also increase the occurrence of programmed cell death (apoptosis). Significance: Thus these agents are potential candidates for the therapy of conditions characterized by ongoing (chronic) inflammation and its associated pain.
- Kattamuri, Padmanabha V.,Salmonsen, Rebecca,McQuain, Catherine,Burstein, Sumner,Sun, Hao,Li, Guigen
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p. 506 - 511
(2013/04/23)
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- Nucleophilic carbene-catalyzed redox-esterification reaction of α-halo-α,β-unsaturated aldehyde
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A nucleophilic carbene catalyzed redox esterification between α-halo-α,β-unsaturated aldehydes and various alcohols has been developed. Interestingly, the reaction provided α,β-unsaturated esters instead of the saturated α-halo substituted esters as the only product in good to high yield with excellent trans-selectivity, presumably via the umpolung-halo-elimination pathway.
- Wang, Xiang-Bo,Zou, Xiao-Lei,Du, Guang-Fen,Liu, Zhi-Yong,Dai, Bin
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p. 6498 - 6503
(2012/08/27)
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- Design, synthesis, and preliminary evaluation of substituted cinnamic acid esters as selective matrix metalloproteinase inhibitors
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Strategy, Management and Health Policy Preclinical Research Substituted cinnamic acid esters with extended P1' groups were synthesized using microwave irradiation and tested for their inhibitory activities on matrix metalloproteinase (MMP)-1, MMP-2, and MMP-9. Preliminary structure-activity relationship analysis and docking studies showed that hydroxyl groups in the benzene ring and the presence of extended spatial structures in the carboxylic acid played key roles in the MMP-2 and MMP-9 inhibitory activity and selectivity over MMP-1.
- Shi, Zhi-Hao,Li, Nian-Guang,Shi, Qian-Ping,Hao-Tang,Tang, Yu-Ping
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p. 317 - 324,8
(2020/07/30)
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- Nhc-catalyzed michael addition to α,β-unsaturated aldehydes by redox activation
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Through oxidative carbene catalysis the reactivity of enals can be reversed at the β position from the typical electrophilic to nucleophilic (homoenolate chemistry) further to electrophilic reactivity by two consecutive umpolung processes. These redox-act
- De Sarkar, Suman,Studer, Armido
-
supporting information; experimental part
p. 9266 - 9269
(2011/02/25)
-
- Towards the catalytic formation of α,β-vinylesters and alkoxy substituted γ-lactones
-
A facile, one pot, high yield synthesis of α,β-vinylester (1-14) and alkoxy substituted γ-lactones (15-28) has been achieved by the photochemical reaction of terminal acetylene (ferrocenyl phenyl trimethylsillyl, hexyl and cyclohexyl) with alcohol (methanol, ethanol and isopropanol) and carbon monoxide in presence of iron pentacarbonyl as a catalyst. The selectivity of the compounds depends on the time of photolysis of the reaction as well as the solvent used. A stable reaction intermediate ferrole was isolated, and further photolysis with alcohols, resulted in the formation of α,β-vinylester. All the compounds were fully characterised by spectroscopic methods and the molecular structures of compounds 1, 16, 17 and 20 were established crystallographically.
- Mathur, Pradeep,Joshi, Raj Kumar,Jha, Badrinath,Singh, Amrendra K.,Mobin, Shaikh M.
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experimental part
p. 2687 - 2694
(2010/11/21)
-
- A synthesis of sulfonamide analogs of platensimycin employing a palladium-mediated carbonylation strategy
-
The monodentate ligand 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phospha-adamantane (PA-Ph) is shown to be highly effective in palladium-catalyzed carbonylative cross-coupling. Aryl and vinyl halides were efficiently converted to carboxylic acids, amides and to primary, secondary, and tertiary esters, respectively. Application of the Pd(OAc)2/PA-Ph (1:1) catalyst system proved critical in the methoxycarbonylation of a functionalized nitroresorcinol halide, allowing convenient access to novel platensimycin sulfonamide analogs.
- McNulty, James,Nair, Jerald J.,Capretta, Alfredo
-
scheme or table
p. 4087 - 4091
(2009/12/01)
-
- Efficient palladium-catalysed carbonylative and Suzuki-Miyaura cross-coupling reactions with bis(di-tert-butylphosphino)-o-xylene
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The use of the ligand bis(di-tert-butylphosphino)-o-xylene (dtbpx) in palladium-catalysed carbonylative and Suzuki-Miyaura cross-coupling reactions is described. Aryl and vinyl halides readily entered into the carbonylative catalytic cycle affording carboxylic acids, amides as well as primary, secondary and tertiary esters, respectively, in good yields. Aryl iodides, bromides and chlorides gave high yields of biphenyl products upon reaction with both activated and unactivated boronic acids.
- McNulty, James,Nair, Jerald J.,Sliwinski, Marcin,Robertson, Al J.
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scheme or table
p. 2342 - 2346
(2009/08/17)
-
- Single step green process for the preparation of substituted cinnamic esters with trans-selectivity
-
The invention provides a green process for direct oxidation of a large number of substituted or unsubstituted cinnamaldehydes or cinnamyl alcohols into the corresponding alkyl or aryl cinnamates in one step. The process of the present invention is a convenient and efficient green process for the preparation of various aryl or alkyl cinnamates under conventional, microwave and ultrasound directly from cinnamaldehydes or cinnamyl alcohols in the presence of an oxidizing agent, catalyst and an alcohol, with or without an organic solvent. These esters are immensely important compounds in flavor, perfumery and pharmaceutical industries. There are several prior arts available for the preparation of cinnamic esters, but all of them suffer from deficiencies such as use of expensive reagents and catalysts, harsh reaction conditions, use of toxic chemicals and others. In contrast, the present methodology is extremely simple and involves reaction of the substrate with an oxidizing agent mixed with a homogeneous or heterogeneous catalyst and an alcohol with or without organic solvent by stirring at room temperature or refluxing or under microwave or ultrasound irradiation to get the requisite products.
- -
-
Page/Page column 7
(2008/06/13)
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- Structure-activity relationships of phenylpropanoids as antifeedants for the pine weevil Hylobius abietis
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Ethyl cinnamate has been isolated from the bark of Pinus contorta in the search for antifeedants for the pine weevil, Hylobius abietis. Based on this lead compound, a number of structurally related compounds were synthesized and tested. The usability of the Topliss scheme, a flow diagram previously used in numerous structure-activity relationship (SAR) studies, was evaluated in an attempt to find the most potent antifeedants. The scheme was initially followed stepwise; subsequently, all compounds found in the scheme were compared. In total, 51 phenylpropanoids were tested and analyzed for SARs by using arguments from the field of medicinal chemistry (rational drug design). Individual Hansch parameters based on hydrophobicity, steric, and electronic properties were examined. The effects of position and numbers of substituents on the aromatic ring, the effects of conjugation in the molecules, and the effects of the properties of the parent alcohol part of the esters were also evaluated. It proved difficult to find strong SARs derived from single physicochemical descriptors, but our study led to numerous new, potent, phenylpropanoid antifeedants for the pine weevil. Among the most potent were methyl 3-phenylpropanoates monosubstituted with chloro, fluoro, or methyl groups and the 3,4-dichlorinated methyl 3-phenylpropanoate.
- Bohman,Nordlander,Nordenhem,Sunnerheim,Borg-Karlson,Unelius
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p. 339 - 352
(2008/09/18)
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- Efficient carbonylation reactions in phosphonium salt ionic liquids: Anionic effects
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(Formula Presented) Application of phosphonium salt ionic liquids in the carbonylation of aryl and vinyl halides is presented. Anionic effects were uncovered with the bromide ionic liquid emerging as the superior media. Acid bromide intermediates were detected in control experiments providing an extended view on the overall catalytic cycle involved. Solvent-free product isolation and recycling of the ionic liquid containing active Pd-catalyst are also demonstrated.
- McNulty, James,Nair, Jerald J.,Robertson, Al
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p. 4575 - 4578
(2008/03/12)
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- An efficient chemoselective strategy for the preparation of (E)-cinnamic esters from cinnamaldehydes using heterogeneous catalyst and DDQ
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An efficient chemoselective protocol is developed for the synthesis of (E)-cinnamic esters from substituted cinnamaldehydes or cinnamyl alcohols using a combination of DDQ and heterogeneous catalyst under microwave irradiation. The method showed remarkable selectivity for cinnamaldehydes over aliphatic and aromatic aldehydes, which is a novel finding. The results demonstrate that the developed protocol can be a useful synthetic tool for chemoselective esterification in total synthesis of complex organic compounds.
- Sinha, Arun K.,Sharma, Anuj,Swaroop, Anand,Kumar, Vinod
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p. 1000 - 1007
(2007/10/03)
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- Tandem oxidation of allylic and benzylic alcohols to esters catalyzed by N-heterocyclic carbenes
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(Chemical Equation Presented) N-Heterocyclic carbenes catalyze the oxidation of allylic, propargylic, and benzylic alcohols to esters with manganese(IV) oxide in excellent yields. A variety of ester derivatives can be synthesized, including protected carboxylates. This one-pot tandem oxidation represents the first organocatalytic oxidation of alcohols to esters. Saturated esters can also be accessed from aldehydes using this method. Through the utilization of a chiral catalyst, the acyl-heteroazolium intermediate becomes a chiral acylating agent, which can desymmetrize meso-1,2-diols.
- Maki, Brooks E.,Chan, Audrey,Phillips, Eric M.,Scheidt, Karl A.
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p. 371 - 374
(2007/10/03)
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- Quantitative structure-activity relationships of pine weevil antifeedants, a multivariate approach
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Antifeedant activity of mainly phenylpropanoic, cinnamic, and benzoic acids esters was tested on the pine weevil, Hylobius abietis (L.). Of 105 compounds screened for activity, 9 phenylpropanoates, 3 cinnamates, and 4 benzoates were found to be highly active antifeedants. To understand the structure-activity relationships of these compounds, a multivariate analysis study was performed. A number of molecular and substituent descriptors were calculated and correlated to results from two-choice feeding tests with H. abietis. Three local models were developed that had good internal predictive ability. External test sets showed moderate predictivity. In general, low polarity, small size, and high lipophilicity were characteristics for compounds having good antifeedant activity.
- Sunnerheim, Kerstin,Nordqvist, Anneli,Nordlander, Goeran,Borg-Karlson, Anna-Karin,Unelius, C. Rickard,Bohman, Bjoern,Nordenhem, Henrik,Hellqvist, Claes,Karlen, Anders
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p. 9365 - 9372
(2008/03/17)
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- Stereoselective synthesis of (E)-α,β-unsaturated esters via carbene-catalyzed redox esterification
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Stereoselective, carbene-mediated redox esterification of alkynyl aldehydes provides mild and atom economical access to (E)-configurated, α,β-unsaturated carboxylic esters. The organocatalytic method relies on the generation of activated carboxylates via extended/conjugated umpolung in the presence of catalytic amounts of carbene precursor and base.
- Zeitler, Kirsten
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p. 637 - 640
(2007/10/03)
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- An asymmetric aminohydroxylation route to (+)-L-733,060
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An enantioselective synthesis of (+)-L-733,060 starting from cinnamic acid using Sharpless asymmetric aminohydroxylation and Wittig reactions as the key steps is described.
- Kandula, Subba Rao V.,Kumar, Pradeep
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p. 3579 - 3583
(2007/10/03)
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- Esters, amides and substituted derivatives of cinnamic acid: Synthesis, antimicrobial activity and QSAR investigations
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A series of esters (Ia-k), substituted derivatives (II a-d) and amides (IIIa-q) of cinnamic acid were synthesized and evaluated as antibacterial and antifungal agents. All the derivatives belonging to the series I, II and III showed antimicrobial activity comparable to the standard. Compounds If and IIc proved to be the most effective compounds. Quantitative structure-activity relationship (QSAR) investigation with multiple linear regression analysis was applied to find a correlation between different calculated physicochemical parameters of the compounds and biological activity. The quantitative models relating the structural features of cinnamic acid derivatives Ia-k, II a-d and IIIa-q and their antimicrobial activity showed that Gram negative Escherichia coli and Candida albicans (fungus) were the most sensitive microorganisms.
- Narasimhan, Balasubramanian,Belsare, Deepak,Pharande, Devayani,Mourya, Vishnukant,Dhake, Avinash
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p. 827 - 834
(2007/10/03)
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- Pd-catalyzed carbonylative cross-coupling reactions by triorganoindiums: Highly efficient transfer of organic groups attached to indium under atmospheric pressure
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(Matrix presented) A highly atom-efficient synthetic method of unsymmetrical ketones was developed by using trialkyl- and triarylindiums, which could be employed as effective cross-coupling partners in Pd-catalyzed carbonylative cross-coupling reactions with a variety of organic electrophiles. The present method produced unsymmetrical ketones and 1,4-diacylbenzenes in good yields with highly efficient transfer of almost all the organic groups attached to the indium under atmospheric pressure of CO gas in THF at 66°C.
- Lee, Phil Ho,Lee, Sung Wook,Lee, Kooyeon
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p. 1103 - 1106
(2007/10/03)
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- Esters and amides from activated alcohols using manganese(IV) dioxide: Tandem oxidation processes
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Manganese(IV) dioxide can be used in conjunction with sodium cyanide in THF-methanol or in methanol alone for the direct conversion of activated alcohols into methyl esters. Ethyl and isopropyl esters can also be prepared. Similarly, use of manganese(IV) dioxide and sodium cyanide in THF containing ammonia or primary amines can be used to convert alcohols into the corresponding amides. Several activated alcohols and one non-activated alcohol example are reported.
- Foot, Jonathan S.,Kanno, Hisashi,Giblin, Gerard M. P.,Taylor, Richard J. K.
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p. 1055 - 1064
(2007/10/03)
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- Reductions of carboxylic acids and esters with NaBH4 in diglyme at 162°C
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Aromatic esters, including the extremely sterically hindered ester: tamyl 2-chlorobenzoate, are readily reduced to the corresponding benzyl alcohols in high yield with NaBH4 in refluxing diglyme (162°C). In sharp contrast, aliphatic esters usually gave only low yields of alcohols. Instead, diglyme fragmentation products are formed which undergo transesterification reactions, producing complex product mixtures including products such as RCOOCH2CH2OCH3. The mechanism of this process involves sodium borohydride-induced SN2 cleavage of diglyme (hydride attack) at high temperatures. However, when the extremely electron rich, 3,4,5-trimethoxybenzoic acid is treated with NaBH4/diglyme at 162°C (with or without an equivalent of LiCl), no 3,4,5-trimethyoxybenzyl alcohol is formed. The electron rich and hindered ester, t-amyl-3,4,5-trimethoxybenzoate, also does not reduce under these conditions (with or without LiCl). However, both methyl and isopropyl 3,4,5-trimethoxybenzoate esters were converted into 3,4,5-trimethyoxybenzyl alcohol in good yields in NaBH4/diglyme/LiCl at 162°C. These reductions did not occur unless LiCl was present, illustrating the electron releasing effect of the three methoxy functions which reduce the carbonyl group's reactivity.
- Zhu, Hua-Jie,Pittman Jr., Charles U.
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p. 1733 - 1750
(2007/10/03)
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- Tandem oxidation processes: The direct conversion of activated alcohols into esters and amides
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The direct conversion of primary alcohols into methyl esters and amides using manganese dioxide and sodium cyanide with methanol or the appropriate amine is reported. These transformations, which proceed via an in situ four step, double oxidation sequence, have been applied to a range of benzylic, heterocyclic, allylic and propargylic alcohols.
- Foot, Jonathan S.,Kanno, Hisashi,Giblin, Gerard M. P.,Taylor, Richard J. K.
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p. 1293 - 1295
(2007/10/03)
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- Improved Cs2CO3 promoted O-alkylation of acids
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Cesium carbonate mediated O-alkylation of carboxylic acids was efficiently carried out under mild in situ conditions to give the corresponding esters exclusively. Chiral templates including α-hydroxy and α-alkoxy acids were also converted to their corresponding esters with no observed racemization.
- Parrish, Jay P.,Dueno, Eric E.,Kim, Seok-In,Jung, Kyung Woon
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p. 2687 - 2700
(2007/10/03)
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- Esterification in dry media using ferric perchlorate adsorbed on silica gel
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Adsorption of Fe(ClO4)3(H2O)6 onto chromatographic grade silica gel in the presence of alcohol ( to be used for esterification ) produces a supported reagent, Fe(ClO4)3(ROH)6/SiO2. This reagent, has been found effective for the rapid and high yield of esters, on grinding in the presence of carboxylic acids using pestle and mortar in the solid state.
- Parmar, Anupama,Kaur, Jatinder,Goyal, Rita,Kumar, Baldev,Kumar, Harish
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p. 2821 - 2826
(2007/10/03)
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- Enantioselective Catalytic Epoxidation of Cinnamate Esters
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A broad study of the (salen)Mn(III)-catalyzed asymmetric epoxidation of cis-cinnamate esters reveals that the steric properties of the ester group have a profound influence on enantioselectivity in the epoxidation reaction, with bulkier esters affording highest ee's.The sensitivity of the reaction selectivity to the steric properties of the cis-alkene are consistent with a "skewed" side-on approach of olefin to the metal -oxo.The electronic properties of the substrate arene ring substituents do not correlate with epoxidation ee, but instead with the cis/trans partitioning of product formation.Evidence is provided for a non-polar inter mediate in a stepwise oxygen-atom-transfer mechanism.The presence of pyridine N-oxide derivatives has a significant effect on catalysts rates and total turnovers, but negligible influence on the stereoselectivity of epoxidation.A mechanistic basis for the role of these additives is proposed.The synthetic applicability of the cinnamate epoxidation methodology is illustrated in the highly enantioslective synthesis of diltiazem.
- Jacobsen, Eric N.,Deng, Li,Furukawa, Yoshiro,Martinez, Luis E.
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p. 4323 - 4334
(2007/10/02)
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- REACTION OF BENZYLIDENEBENZYLAMINE WITH CINNAMIC ACID DERIVATIVES UNDER CONDITIONS OF PHASE-TRANSFER CATALYSIS. I. SYNTHESIS OF β-ARYL-γ-PHENYL-γ-AMINOBUTYRIC ACIDS AND THEIR DERIVATIVES
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The reaction of benzylidenebenzylamine with the esters of substituted cinnamic acids under the conditions of phase-transfer catalysis gives high yields of β-aryl-γ-phenyl-γ-aminobutyric acids and their derivatives (hydrochlorides, 4-aryl-5-phenyl-2-pyrrolidones).
- Potapov, V. M.,Gracheva, R. A.,Sivov, N. A.,Savina, S. A.,Sivova, L. A.
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p. 1694 - 1699
(2007/10/02)
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