- Preparation of 4-Hydroxy-3-Substituted, 2H-1-Benzopyran-2-ones and 2H-1-Benzothiopyran-2-ones from Carboxylic Esters and Methyl Salicylates or Methyl Thiosalicylate
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C(α)-Carboxylic acid esters were treated with excess lithium diisopropylamide, condensed with methyl salicylates or methyl thiosalicylate, followed by acid cyclization to either 4-hydroxy-3-substituted, 2H-1-benzopyran-2-ones (coumarins), or 2H-1-benzothiopyran-2-ones (thiocoumarins).
- Davis, Sharon E.,Church, A. Cameron,Tummons, Rebecca C.,Beam, Charles F.
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- Copper(II)-Catalyzed Tandem Reaction: Synthesis of Furo[3,2- c]coumarin Derivatives and Evaluation for Photophysical Properties
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An efficient protocol for synthesizing furo[3,2-c]coumarin derivatives is described. The novel reaction could afford the desired furocoumarins with good to excellent yields in a mild and rapid manner. Large substrate scope screening and scale-up preparation have also been accomplished, and selected compounds were evaluated for their photophysical properties.
- Feng, Xi,Qin, Zhen,Cheng, Xinying,Liu, Dongyu,Peng, Yinghe,Huang, Huidan,Song, Bin,Bian, Jinlei,Li, Zhiyu
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supporting information
p. 12537 - 12548
(2021/09/20)
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- Rh-Catalyzed domino synthesis of 4-hydroxy-3-methylcoumarins via branch-selective hydroacylation
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A Rh-catalyzed domino synthesis of 4-hydroxy-3-methylcoumarins via branch-selective hydroacylation of acrylates and acrylamides using salicylaldehydes is described. This protocol under phosphine-free Rh-catalyzed conditions provided 4-hydroxy-3-methylcoum
- Rao, Maddali L.N.,Ramakrishna, Boddu S.,Nand, Sachchida
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supporting information
p. 9275 - 9279
(2019/11/13)
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- NEW ANTIBACTERIAL COMPOUNDS
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The present invention relates to novel antibacterial compounds, pharmaceutical compositions containing them and their use as antimicrobials.
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Page/Page column 56-59
(2016/07/05)
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- A Baker-Venkataraman retro-Claisen cascade delivers a novel alkyl migration process for the synthesis of amides
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A simple extension of the carbamoyl Baker-Venkataraman rearrangement has been developed. If residual water in the reaction is not strictly excluded a Baker-Venkataraman retro-Claisen cascade takes place, giving amide products, in which an alkyl group apparently migrates between two functionalities of the substrate.
- Ameen, Dana,Snape, Timothy J.
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p. 1816 - 1819
(2015/03/30)
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- Synthesis of 3-aminomethyl-4-hydroxycoumarins and their retro-Mannich reaction in dimethyl sulfoxide
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Hydrogenation of 3-formyl-4-hydroxycoumarin aliphatic imines leads to 3-aminomethyl-4-hydroxycoumarins, which undergo a retro-Mannich reaction in dimethyl sulfoxide containing even traces of water.
- Milevskii,Chibisova,Solovéva,Sukhorukov, A. Yu.,Traven
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p. 423 - 428
(2015/10/29)
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- Synthesis of coumarins, 4-hydroxycoumarins, and 4-hydroxyquinolinones by tellurium-triggered cyclizations
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Coumarins, 4-hydroxycoumarins, and 4-hydroxyquinolin-2(1H)-ones can be conveniently prepared by treatment of α-halocarboxylic acid esters of salicylaldehyde, o-hydroxyacetophenone, methyl salicylate, and methyl N-methyl- or N-phenylanthranilates with sodium or lithium telluride. Phenylketene formation competes with cyclization of the α-chlorophenylacetate ester of methyl salicylate as demonstrated by a trapping experiment with benzylamine. Elemental tellurium may be recovered and reused.
- Dittmer, Donald C.,Li, Qun,Avilov, Dimitry V.
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p. 4682 - 4686
(2007/10/03)
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- Directed ortho metalation-cross coupling links. Carbamoyl rendition of the Baker-Venkataraman rearrangement. Regiospecific route to substituted 4- hydroxycoumarins
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A new carbamoyl Baker-Venkataraman rearrangement (4) which allows a general synthesis of substituted 4-hydroxycoumarins 8 in 43-82% overall yields is described; the intermediate arylketones 6 are efficiently prepared (59-91% yields) via a Directed ortho Metalation - Negishi cross coupling protocol from arylcarbamates 5 and the overall sequence provides a regiospecific anionic Friedel-Crafts complement for the construction of ortho-acyl phenols and coumarins.
- Kalinin, Alexey V.,Da Silva, Alcides J. M.,Lopes, Claudio C.,Lopes, Rosangela S. C.,Snieckus, Victor
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p. 4995 - 4998
(2007/10/03)
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- The Chemistry of Coumarin Derivatives Synthesis of 3-Alkyl-4-hydroxycoumarins by Reductive Fragmentation of 3,3'-Alkylidene-4,4'-dihydroxybis
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Treatment of 3,3'-alkylidene-4,4'-dihydroxybis 1 with NaBH3CN in refluxing MeOH affords 3-alkyl-4-hydroxycoumarins 2 and 4-hydroxycoumarin (3; Scheme 1).The reaction may take place via hydride trapping of alkylidenechromandiones C formed from 1 in a retro-Michael reaction.Such a retro-Michael reaction of 1 might be biologically relevant.The presence of C during the reductive fragmentation 1 --> 2 is suggested by Diels-Alder and nucleophilic trapping of the alkylidenechromandiones C as well as from cross-over experiments with coumarins other than 3 (see Scheme 2).The reductive fragmentation of 1 allows the chemo- and regioselective synthesis of a variety of 3-alkyl-4-hydroxycoumarins 2 (see Table).
- Appendino, Giovanni,Cravotto, Giancarlo,Tagliapietra, Silvia,Ferraro, Stefano,Nano, Gian Mario,Palmisano, Giovanni
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p. 1451 - 1458
(2007/10/02)
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- Facile Synthesis of 4-Hydroxycoumarins by Sulfur-Assisted Carbonylation of 2'-Hydroxyacetophenones with Carbon Monoxide
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4-Hydroxycoumarins (4-hydroxy-2-oxo-2H-1-benzopyrans) were synthesized in good to excellent yields by C-carbonylation of 2'-hydroxyacetophenones with carbon monoxide in the presence of sulfur and bases.This is the first example of sulfur-assisted C-carbonylation with carbon monoxide.
- Mizuno, Takumi,Nishiguchi, Ikuzo,Hirashima, Tsuneaki,Ogawa, Akiya,Kambe, Nobuaki,Sonoda, Noboru
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p. 257 - 259
(2007/10/02)
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- SELENIUM ASSISTED CARBONYLATION OF ALKYL ARYL KETONES WITH CARBON MONOXIDE
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Selenium assisted carbonylation of alkyl aryl ketones with carbon monoxide leading to formation of 1,3-dicarbonyl compounds as C-carbonylated products is described. o-Hydroxyacetophenone (7a) and its derivatives (7b, 7c and 7d) have been converted to the corresponding 4-hydroxycoumarins (8a, 8b, 8c and 8d) in moderate to quantitative yields by treatment with an equivalent of selenium and carbon monoxide with concomitant formation of hydrogen selenide (9) (Eq.(8)).It was further revealed that oxidation of in situ formed hydrogen selenide to selenium with an appropriate oxidizing agent such as nitrobenzene permitted catalytic use of selenium for the carbonylation of 7.Possible rationalizations for the formation of 4-hydroxycoumarins are suggested.
- Ogawa, Akiya,Kambe, Nobuaki,Murai, Shinji,Sonoda, Noboru
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p. 4813 - 4820
(2007/10/02)
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- A Method for the C-Methylation of Cyclic β-Dicarbonyl Compounds
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Cyclic β-dicarbonyl compounds (1, 4, 7, 10) were reacted with either aniline or urea in the presence of trimethoxymethane to give the enamines 2, 5, 8 and 11, resp.The latter were reduced with hydrogen over palladium-charcoal or with the dimethylamine-bor
- Ziegler, Erich,Wolfbeis, Otto S.,Trummer, Iris
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p. 105 - 107
(2007/10/02)
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- Model Studies for a Molecular Mechanism of Action of Oral Anticoagulants
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Warfarin , a potent oral anticoagulant agent, is known to inhibit the enzyme vitamin K epoxide reductase.The molecular mechanism of inhibition, however, is not known.It is proposed that the two major classes of oral anticoagulants, the 3-substituted-4-hydroxycoumarins and the 2-substituted-1,3-indandiones, are mechanism-based inactivators of this enzyme.The proposed mechanism of inactivation involves enzyme-catalyzed activation of the oral anticoagulants by tautomerization to the hypothetically reactive diketo forms which then undergo attack by active-site nucleophiles.In order to test the chemistry of this proposal, it is shown that the two classes of oral anticoagulants are unreactive toward bases and nucleophiles (except for deprotonation), until they are electrophilically substituted at the 3-position of the coumarins or at the 2 position of the indandiones.These model compounds for the proposed enzyme-generated reactive intermediates, then, are shown to be highly reactive toward a variety of nucleophiles and support the hypothesis that the oral anticoagulants are converted by vitamin K epoxide reductase into reactive compounds which can acylate an active-site nucleophile and thereby inactivate the enzyme.
- Silverman, Richard B.
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p. 3910 - 3915
(2007/10/02)
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