- 13C NMR Spectral Studies of Some Methoxycoumarin Derivatives. A Re-assignment for Citropten (Limettin) and an Examination of Peri-Proximity Effects for the Methyl-Methoxy and Methoxy-Methyl Couples
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The 13C chemical shifts and 13C-1H coupling constants of some methoxycoumarins are reported.Some earlier spectral assignments, including those for citropten (limettin), require revision.Methoxy substituent effects on long-range 13C-1H couplings in coumarins are highlighted.Peri-proximity effects for the methyl-methoxy and mehoxy-methyl couples are derived, and the value of these effects in the assignment of peri-substituted compounds is illustrated. KEY WORDS 13C NMR Methoxycoumarins Citropten Limettin 13C-1H coupling constant Peri-proximity effects
- Osborne, Alan G.
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- Metal-free, Br?nsted acid-mediated synthesis of coumarin derivatives from phenols and propiolic acids
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A novel synthesis of coumarin derivatives by Br?nsted acid-mediated condensation and intramolecular cyclization of phenols and propiolic acids was reported. This transformation requires the use of TfOH in place of a conventional metal mediator, and it occurs under mild conditions and provides rapid access to coumarin derivatives in good yields.
- Choi, Hyuck,Kim, Jaehyun,Lee, Kooyeon
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supporting information
p. 3600 - 3603
(2016/07/21)
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- Process for preparing coumarin derivatives using phenol and propiolic acid
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Provided is a manufacturing method of coumarin derivative. The manufacturing method of coumarin derivative comprises a step of making a phenol compound react with a propiolic acid compound. According to the present invention, the manufacturing method of coumarin derivative is quick and efficient, and is useful to fields requiring synthesis of coumarin derivatives of various structures.COPYRIGHT KIPO 2016
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Paragraph 0119; 0120
(2017/01/12)
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- Synthetic models related to methoxalen and menthofuran-cytochrome P450 (CYP) 2A6 interactions. Benzofuran and coumarin derivatives as potent and selective inhibitors of CYP2A6
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Human microsomal cytochrome P450 (CYP) 2A6 contributes extensively to nicotine detoxication but also activates tobacco-specific procarcinogens to mutagenic products. We prepared a series of benzofuran and coumarin derivatives that have inhibitory effects on the activity of human CYP2A6. The reported compounds methoxalen and menthofuran had potent inhibitory effects on the activity of CYP2A6 with IC50 values of 0.47 μM and 1.27 μM, respectively. Synthetic benzofuran (4-methoxybenzofuran: IC50=2.20 μM) and coumarin (5-methoxycoumarin: IC50=0.13 μM and 6-methoxycoumarin: IC50=0.64 μM) derivatives, which have more selective effects than those of methoxalen and menthofuran, exhibited comparable activities against CYP2A6. These compounds can be used as a lead compounds in the design of CYP2A6 inhibitor drugs to reduce smoking and tobacco-related cancers.
- Yamaguchi, Yuki,Akimoto, Ichie,Motegi, Kyoko,Yoshimura, Teruki,Wada, Keiji,Nishizono, Naozumi,Oda, Kazuaki
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p. 997 - 1001
(2013/11/19)
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- Synthesis of coumarins and neoflavones through zinc chloride catalyzed hydroarylation of acetylenic esters with phenols
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Acetylenic esters react with oxygenated phenols under solvent-free conditions in the presence of only 5 mol% of zinc chloride as a catalyst to give coumarins and neoflavones in reasonable-to-good yields. Georg Thieme Verlag Stuttgart. New York.
- Leao, Raquel A. C.,Def.demoraes, Paula,Pedro, Marcella C. B. C.,Costa, Paulo R. R.
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experimental part
p. 3692 - 3696
(2011/12/16)
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- New approach for the construction of the coumarin frame and application in the total synthesis of natural products
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A new synthetic approach is described for building the coumarin scaffold through the Lewis acid-promoted cyclization of novel aryl 3-(dimethylamino)prop- 2-enoates 2a - 2f. The latter precursors were prepared via aminomethylenation of the corresponding aryl acetates 4a - 4f with the Bredereck reagent. This approach was used for the synthesis of biologically active natural compounds 1a - 1f, through a three-step procedure starting from the corresponding phenols.
- Jerezano, Alberto,Jimenez, Fabiola,Del Carmen Cruz, Maria,Montiel, Luisa E.,Delgado, Francisco,Tamariz, Joaquin
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p. 185 - 198
(2011/04/17)
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- Improved synthesis of coumarins by iron(III)-catalyzed cascade reaction of propiolic acids and phenols
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The reaction of propiolic acids with phenols in the presence of FeClAgOTf catalyst proceeded efficiently in a mixed solvent of trifluoroacetic acid and 1,2-dichloroethane, and provided coumarins in good to high yields. This iron-catalyzed reaction offers a much-improved synthesis of coumarins. Thieme Stuttgart New York.
- Kutubi, Md. Shahajahan,Hashimoto, Takuya,Kitamura, Tsugio
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experimental part
p. 1283 - 1289
(2011/05/19)
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- Synthesis of coumarins by Pt-catalyzed hydroarylation of propiolic acids with phenols
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Synthesis of coumarins from phenols and propiolic acids was examined by using a Pt catalyst such as PtCl2/AgOTf, K2PtCl4/AgOTf, and K2PtCl4/AgOAc. Propiolic acid reacted even with less reactive phenols in trifluoroacetic acid to give coumarins and dihydrocoumarins. In the case of substituted propiolic acids, phenylpropiolic acid and 2-octynoic acid, the reactions proceeded selectively to afford coumarins in good to high yields.
- Oyamada, Juzo,Kitamura, Tsugio
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p. 6918 - 6925
(2007/10/03)
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- A convenient synthesis of coumarins by palladium(II)-catalyzed reaction of phenols with propiolic acids
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A direct route to coumarin derivatives from phenols and propiolic acids has been developed. Phenols react with propiolic acids in the presence of Pd(OAc)2 as a catalyst to give coumarins in good yields. The simple process occurs under mild conditions without any additives.
- Kotani, Masashi,Yamamoto, Kiyomi,Oyamada, Juzo,Fujiwara, Yuzo,Kitamura, Tsugio
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p. 1466 - 1470
(2007/10/03)
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- Atom economy. Palladium-catalyzed formation of coumarins by addition of phenols and alkynoates via a net C-H insertion
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A strategy to achieve ortho substitution of phenols initiated by an ortho-palladation to create coumarins was examined. Indeed, treatment of alkynoates with electron-rich phenols in the presence of a palladium catalyst and an acid does generate coumarins. The scope of the reaction with respect to the phenol and the alkynoates is defined. With unsymmetrical aromatic substrates, generally good regioselectivity that reflects the HOMO coefficients can be observed. In the course of these studies, numerous important naturally occurring coumarins have been synthesized, including fraxinol methyl ether, ayapin, herniarin, xanthoxyletin, and alloxanthoxyletin. The fact that a Pd(0) is the precatalyst rather than a Pd(+2) species and that an acid that reduces Pd(+2) salts, formic acid, functions better than other carboxylic acids raises doubts about the initial working hypothesis. A novel mechanism involving a palladium phenoxide formed from a hydridopalladium carboxylate and phenol is invoked to rationalize the results.
- Trost, Barry M.,Toste, F. Dean,Greenman, Kevin
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p. 4518 - 4526
(2007/10/03)
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- Further studies of orientation effects in the Pechmann synthesis of coumarins
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A study of orientation effects in the Pechmann synthesis with some meta-substituted phenols is presented. Variation of the reaction conditions with malic acid indicates that whilst the proportion of 5-chlorocoumarin diminishes at higher temperatures that of 5-methoxycoumarin increases, accompanied by cleavage of the ether function under certain conditions. Reactions with ethyl acetoacetate give only the 4,7-isomers. Peri-substituent effects in 1 H and 13C NMR spectroscopy have been used for product identification.
- Osborne, Alan G.,Andrews, Steven J.,Mower, Rachel
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p. 319 - 338
(2007/10/03)
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- Enolethers, XVIII. - A Simple Synthesis of Coumarins
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In boiling 1,2-dichloroethane 3-ethoxyacryloyl chloride (1) reacts with phenols 2 to yield 3-ethoxyacrylates 3, which by treatment with conc. sulfuric acid/10percent SO3 cyclize to give coumarins 9 in good yields.The methoxy-substituted compounds 3d and 3k do not react to coumarins 9 with H2SO4/SO3 but with POCl3/H2O at room temperature.
- Ziegler, Thomas,Moehler, Hans,Effenberger, Franz
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p. 373 - 378
(2007/10/02)
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- Photocyclization of 2,6-Dichlorocinnamic Acid Derivatives to 5-Chlorocoumarin
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On UV irradation, 2,6-dichlorocinnamic acid and its esters undergo photocyclization with elimination of the elements of HCl or RCl (R = alkyl or aryl) to yield 5-chlorocoumarin (2); amide derivatives yield the corresponding imino analogues.Low-temperature
- Arad-Yellin, R.,Green, B. S.,Muszkat, K. A.
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p. 2578 - 2583
(2007/10/02)
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