- Nucleophilic substitution of hydrogen–the Boger reaction sequence as an approach towards 8-(pyridin-2-yl)coumarins
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5,7-Dimethoxy-8-(3,6-diphenylpyridin-2-yl)coumarins were obtained from 5,7-dimethoxycoumarins and 3,6-diphenyl-1,2,4-triazines via the protocol comprising aromatic SNH substitution in the triazine ring followed by the Boger transform
- Fatykhov, Ramil F.,Savchuk, Maria I.,Starnovskaya, Ekaterina S.,Bobkina, Maria V.,Kopchuk, Dmitry S.,Nosova, Emiliya V.,Zyryanov, Grigory V.,Khalymbadzha, Igor A.,Chupakhin, Oleg N.,Charushin, Valery N.,Kartsev, Viktor G.
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Read Online
- Formation of coumarins by palladium(II)-catalyzed reaction of phenols with ethyl acrylates
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The reaction of phenols with ethyl acrylates in the presence of a Pd(OAc)2 catalyst in trifluoroacetic acid did not yield dihydrocoumarins but gave coumarins, in contrast to the reaction of phenols with propiolates. The addition of K2S2O8 as an oxidant increased the yield of coumarins. The reaction of several phenols with ethyl cinnamate, ethyl crotonate, or ethyl acrylate gave the corresponding coumarin derivatives in moderate to good yields. The coumarin formation competed with the oxidative coupling of electron-rich phenols, which reduced the product yield.
- Aoki, Shinya,Oyamada, Juzo,Kitamura, Tsugio
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Read Online
- Synthesis and NMR of 4-Aryl-3,4-dihydrocoumarins and 4-arylcoumarins
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This paper described the synthesis and 1H and 13C NMR chemical shifts of a series of 4-aryl-3,4-dihydrocoumarin and 4-arylcoumarin derivatives based on a combination of 1H and 13C NMR, HSQC and HMBC experiments.
- Sun, Jie,Wang, Yanfeng
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p. 7753 - 7758
(2015/02/02)
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- Antioxidant and antitumor activities of 4-arylcoumarins and 4-aryl-3,4-dihydrocoumarins
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Five 4-arylcoumarins (1c-g) and twelve 3,4-dihydro-4-arylcoumarins (2a-l) were synthesized and tested for antioxidant activity, antitumor activity, toxicity and structure-activity relationships analysis. 4-Arylcoumarins and 3,4-dihydro-4-arylcoumarins tha
- Zhang, Keyun,Ding, Weixian,Sun, Jie,Zhang, Bin,Lu, Fujiao,Lai, Ren,Zou, Yong,Yedid, Gabriel
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supporting information
p. 203 - 210
(2015/02/19)
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- Pd-catalyzed chemo-selective mono-arylations and bis-arylations of functionalized 4-chlorocoumarins with triarylbismuths as threefold arylating reagents
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Cross-coupling reactions of differently substituted 4-chlorocoumarins were studied under palladium catalysis using triarylbismuths as threefold arylating reagents. The high reactivity of 4-chlorocoumarins was demonstrated delivering mono- and bis-arylation products in a chemo-selective manner. The reaction conditions employed are simple, robust and the threefold coupling reactivity of triarylbismuth reagents was witnessed with good to high yields in 2-4 h conditions. The utility of the methodology was explored in the synthesis of a few natural occurring neoflavones (3.27-3.30). In addition, the 4-arylcoumarin 3.1 product is a useful precursor for the preparation of (R)-tolterodine.
- Rao, Maddali L.N.,Kumar, Abhijeet
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p. 6995 - 7005
(2015/03/14)
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- A convenient solid-phase synthesis of coumarins by TMSOTf-catalyzed intramolecular seleno-arylation of tethered alkenes
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TMSOTf-catalyzed intramolecular seleno-arylation of tethered alkenes was performed using polystyrene-supported succinimidyl selenide as the selenium source. This catalytic process provides an efficient method for the regioselective synthesis of dihydrocou
- Tang,Li, Wen,Gao, Zhangyong
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experimental part
p. 907 - 912
(2012/05/20)
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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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- Efficient synthesis and biological evaluation of 4-arylcoumarin derivatives
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Two bioactive natural 4-arylcoumarins, 5,7,4′-trimethoxy-4- phenylcoumarin (1a), 5,7-dimethoxy-4-phenylcoumarin (1b) and five closely related derivatives 1c-g were synthesized. In vitro evaluation with a catechol subunit for antioxidant and antimicrobial activity, these compounds using standard methods showed that compounds 1d, 1f displayed promise radical scavenging activity and 1f was found to be the most active one against Bacillus dysenteriae.
- Sun, Jie,Ding, Wei Xian,Zhang, Ke Yun,Zou, Yong
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scheme or table
p. 667 - 670
(2012/01/13)
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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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- Concise Synthesis of Anti-HIV-1 Active (+)-Inophyllum B and (+)-Calanolide A by Application of (-)-Quinine-Catalyzed Intramolecular Oxo-Michael Addition
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(-)-Quinine-catalyzed intramolecular oxo-Michael addition (IMA) of 7-hydroxy-5-methoxy-8-tigloylcoumarins was developed for the enantioselective construction of 2,3-dimethyl-4-chromanone systems in the context of the asymmetric synthesis of anti-HIV-1 act
- Sekino, Etsuko,Kumamoto, Takuya,Tanaka, Tomohiro,Ikeda, Tomoko,Ishikawa, Tsutomu
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p. 2760 - 2767
(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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- PdII-Catalyzed Reaction of Phenols with Propiolic Esters. A Single-Step Synthesis of Coumarins
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The intermolecular reaction of phenols with propiolic esters in TFA in the presence of a Pd(OAc)2 catalyst, affording coumarin derivatives, is described. An exclusive formation of 5,6,7-trimethoxy-4-phenylcoumarin was observed in the reaction of 3,4,5-trimethoxyphenol and ethyl phenylpropiolate with a catalytic amount of Pd(OAc)2. The reaction in the absence of Pd(OAc)2 did not give any coumarin at all. Coumarin derivatives were obtained in high yields in the cases of electron-rich phenols, such as 3,4-methylenedioxyphenol, 3-methoxyphenol, 2-naphthol, and 3,5-dimethoxyphenol. Furthermore, the reaction of some phenols with various 2-alkynoates or with diethyl acetylenedicarboxylate gave the corresponding coumarins in good-to-high yields.
- Kitamura, Tsugio,Yamamoto, Kiyomi,Kotani, Masashi,Oyamada, Juzo,Jia, Chengguo,Fujiwara, Yuzo
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p. 1889 - 1895
(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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- Direct synthesis of coumarins by Pd(II)-catalyzed reaction of alkoxyphenols and alkynoates
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Reaction of alkoxyphenols and alkynoates in the presence of a catalytic amount of Pd(OAc)2 in trifluoroacetic acid at room temperature gave coumarin derivatives in high yields. This procedure provides a convenient method for direct synthesis of coumarin derivatives under very mild conditions.
- Oyamada, Juzo,Jia, Chengguo,Fujiwara, Yuzo,Kitamura, Tsugio
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p. 380 - 381
(2007/10/03)
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- Synthesis of neoflavones by Suzuki arylation of 4-substituted coumarins
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Palladium-catalysed coupling of the 4-chloro- or 4-bromo-coumarins 1-4 with arylboronic acids 5-13 under the Suzuki reaction conditions constitutes an efficient access to 4-arylcoumarins. These 4-arylcoumarins can also be obtained in good yields (70-97%)
- Boland, Gerard M.,Donnelly, Dervilla M. X.,Finet, Jean-Pierre,Rea, Martin D.
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p. 2591 - 2597
(2007/10/03)
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- Synthesis of Highly Functionalized Flavones and Chromones Using Cycloacylation Reactions and C-3 Functionalization. A Total Synthesis of Hormothamnione
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The cycloacylations of hydroxy- and methoxy-substituted phenols with aryl- and alkylpropiolic acids using Eaton's reagent (10percent phosphorus pentoxide in methanesulfonic acid) gives highly substituted flavones and chromones in up to 63 percent yield.Styrylchromones were prepared from 2-methylchromones by condensation reactions of the 2-methyl group with various substituted benzaldehydes in sodium ethoxide and ethanol in almost quantitative yield.Methylation or hydroxylation at C-3 of these highly substituted flavones and styrylchromones was accomplished in a highly regioselective manner employing lithium diisopropylamide followed by quenching with an electrophile.Quenching of the initial anion with methyl triflate gave 3-methyl products while quenching of the initial anion with trimethylborate followed by oxidation gave 3-hydroxy products.A total synthesis of the naturally occurring styrylchromone hormothamnione, containing a 3-methyl substituent, is reported by use of these synthetic techniques.
- McGarry, Lynda W.,Detty, Michael R.
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p. 4349 - 4356
(2007/10/02)
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- Carbon-13 NMR Chemical Shift Assignment of Neoflavonoids
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The 13C NMR resonances of some 5,7-dihydroxy- and 5,7-dimethoxy-4-arylcoumarins were assigned by two-dimensional NMR experiments (HETCOR and LONG-RANGE HETCOR) on some key compounds. KEY WORDS 13C NMR chemical shifts Neoflavonoids 5,7-Dihydroxy- and 5,7-d
- Monache, Giuliano Delle,Messana, Irene,Botta, Bruno,Gacs-Baitz, Eszter
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p. 1181 - 1183
(2007/10/02)
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- A Facile Synthesis of 4-Aryl-2H-1-benzopyran-2-ones
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Reaction of 2-hydroxybenzophenones (1, 3, 7, 8) with ethoxycarbonylmethylenetriphenylphosphorane affords 4-aryl-2H-1-benzopyran-2-ones (2, 4-6) in excellent yields. - Keywords: 4-Aryl-2H-1-benzopyran-2-ones; Ethoxycarbonylmethylenetriphenylphosphorane; Friedel-Crafts reaction; 2-Hydroxybenzophenones; Wittig reaction
- Ahluwalia, Vinod K.,Singh, Daljeet,Singh, Rishi P.
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p. 869 - 872
(2007/10/02)
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