2445-83-2Relevant academic research and scientific papers
ORIENTATION EFFECTS IN THE PECHMANN REACTION SYNTHESIS OF 5,6-DIMETHYLCOUMARIN AND AN EXAMINATION OF ORTHO-PROXIMITY EFFECTS IN 13C NMR SPECTROSCOPY
Osborne, A. G.
, p. 2021 - 2025 (1981)
In the Pechmann reaction with malic acid, m-cresol and 3,4-xylenol give mixtures of alkylcoumarins containing about 10percent of the 5- and 5,6-isomers respectively. 7-Alkylcoumarins only are obtained from the reaction with ethylacetoacetate.A study of ortho-proximity effects on the 13C NMR of dimethylcoumarins is reported, and the results have been correlated with similar effects in other aromatic and heteroaromatic systems.
Cycloreversion performance of coumarin and hetero-coumarin dimers under aerobic conditions: Unexpected behavior triggered by UV-A light
Bieniek, Nikolai,Hampp, Norbert,Inacker, Sebastian
, p. 17703 - 17712 (2021/08/30)
Photochemical [2+2]-cycloadditions of coumarin-like monomers are the textbook paradigms of photo-formation and photo-cleavage reactions. The electronic conjugation length of monomers and dimers is quite different which results in almost fully separated UV/Vis absorption bands in the UV-A and UV-C. This feature enables the selective light-controlled conversion between monomeric and dimeric forms by the choice of the appropriate wavelengths. Several applications are based on this kind of reversible photo linker without absorption in the visible range. But which is the best molecule from the coumarin family for such an application? Within this study, we compared the photochemical cleavage behavior of twelve coumarin-type cyclobutane dimers. In particular, the influence of isomer structure and substitution pattern was studied. Two dimers with an unexpected high quantum yield for cyclobutane cleavage were identified. This behavior is explained through the differing ring strain of the cyclobutane moiety. Electron donating substitutions of the framework, e.g. with a methoxy function (+M-effect), leads to a decreased oxidation potential, making the dimers sensitive towards oxidative dimer splitting. This result disqualifies coumarins, e.g. attached to a polymer backbone via an ether bond, often in the 7-position, because of their instabilities and side reactions in an aerobic environment. The methylated dimers (+I-effect) show excellent stability towards this undesired side reaction as well as a high cleavage efficiency upon irradiation with 265 nm. All twelve investigated dimers are ranked for their quantum efficiency and rate constant for cleavage at 265 nm, as well as their oxygen tolerance. As the most promising derivative within our scope for applications the methylated coumarin dimer was identified.
Visible-light promoted oxidative cyclization of cinnamic acid derivatives using xanthone as the photocatalyst
Zhao, Bin,Xu, Bo
supporting information, p. 568 - 573 (2021/02/06)
We have developed an efficient photocatalytic synthesis of coumarin derivativesviaa tandem double bond isomerization/oxidative cyclization of cinnamic acids. Inexpensive and stable xanthone was used as the photocatalyst, and readily available Selectfluor was used as the oxidant. This method tolerates a wide range of functional groups and offers excellent chemical yields in general. Besides, the photocatalytic oxidative cyclization of cinnamic acid esters gives dimerized lignan-type products.
Polyphosphoric acid-promoted synthesis of coumarins lacking substituents at positions 3 and 4
Yang, Li-Shou,Wang, Yu,Wang, En-Hua,Yang, Jan,Pan, Xiong,Liao, Xiu,Yang, Xiao-Sheng
supporting information, p. 1 - 6 (2020/07/25)
Coumarins have recently emerged as a hot topic of research due to their diverse pharmacological properties. This work described a method for the synthesis of 3,4-diunsubstituted coumarins promoted by polyphosphoric acid (PPA) from salicylaldehydes and acetic anhydride. Various coumarins were produced in good to excellent yields.
Synthesis method of coumarin derivatives
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Paragraph 0054-0056, (2020/09/23)
The invention provides a synthesis method of coumarin derivatives. The synthesis method comprises the following steps: adding polyphosphoric acid PPA and a solvent N,N-dimethylformamide DMF, sequentially adding substituted salicylaldehyde and acetic anhydride, and carrying out a heating stirring reaction for 3-6 h under nitrogen protection; and after the reaction is finished, separating and purifying to obtain the coumarin derivative pure products. The synthesis method disclosed by the invention is disclosed for the first time, is short in reaction time, simple to operate, low in catalyst usage amount, cheap, easy to obtain and relatively good in derivative yield, not only provides a new method for synthesizing coumarin derivatives, but also provides more possibilities for large-scale production of products and improvement of production efficiency.
Generation of Alkyl Radical through Direct Excitation of Boracene-Based Alkylborate
Hashizume, Daisuke,Hosoya, Takamitsu,Nakamura, Kei,Ohmiya, Hirohisa,Sato, Yukiya,Sumida, Yuto
supporting information, p. 9938 - 9943 (2020/06/27)
The generation of tertiary, secondary, and primary alkyl radicals has been achieved by the direct visible-light excitation of a boracene-based alkylborate. This system is based on the photophysical properties of the organoboron molecule. The protocol is applicable to decyanoalkylation, Giese addition, and nickel-catalyzed carbon-carbon bond formations such as alkyl-aryl cross-coupling or vicinal alkylarylation of alkenes, enabling the introduction of various C(sp3) fragments to organic molecules.
Metal-free, Br?nsted acid-mediated synthesis of coumarin derivatives from phenols and propiolic acids
Choi, Hyuck,Kim, Jaehyun,Lee, Kooyeon
supporting information, p. 3600 - 3603 (2016/07/21)
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.
Process for preparing coumarin derivatives using phenol and propiolic acid
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Paragraph 0104; 0105, (2017/01/12)
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
Rh-Catalyzed Synthesis of Coumarin Derivatives from Phenolic Acetates and Acrylates via C-H Bond Activation
Gadakh, Sunita K.,Dey, Soumen,Sudalai, Arumugam
, p. 11544 - 11550 (2015/12/04)
An efficient annulation strategy involving the reaction of phenolic acetates with acrylates in the presence of [Rh2(OAc)4] as catalyst and formic acid as reducing agent, leading to the high yield synthesis of coumarin derivatives, has been developed. The addition of NaOAc as a base increased the yield of the products. The reaction is quite successful for both electron-rich as well as electron-deficient phenolic acetates, affording coumarins with excellent regioselectivity, and proceeds via C-H bond activation proven by deuterium incorporation studies.
Assembly of indole fluorophore in situ for hydrogen sulfide signaling through substrate triggered intramolecular reduction-cyclization cascade: A sensitive and selective probe in aqueous solution
Zhou, Ji,Luo, Yuanyuan,Li, Qiang,Shen, Jiaoning,Wang, Rui,Xu, Yufang,Qian, Xuhong
supporting information, p. 2770 - 2773 (2014/07/07)
A novel probe containing the azide-coumarin-aldehyde triad (S1) for hydrogen sulfide (H2S) was developed. The fluorophore for signaling is assembled in situ through a H2S triggered intramolecular reduction-cyclization cascade, and has a concomitant 10-fold enhancement of the fluorescent intensity at 520 nm. Fluorescence imaging of H2S in living cells proved its potential for biological application. the Partner Organisations 2014.
