- ORIENTATION EFFECTS IN THE PECHMANN REACTION SYNTHESIS OF 5,6-DIMETHYLCOUMARIN AND AN EXAMINATION OF ORTHO-PROXIMITY EFFECTS IN 13C NMR SPECTROSCOPY
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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.
- Osborne, A. G.
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- Cycloreversion performance of coumarin and hetero-coumarin dimers under aerobic conditions: Unexpected behavior triggered by UV-A light
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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.
- Bieniek, Nikolai,Hampp, Norbert,Inacker, Sebastian
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p. 17703 - 17712
(2021/08/30)
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- Visible-light promoted oxidative cyclization of cinnamic acid derivatives using xanthone as the photocatalyst
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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.
- Zhao, Bin,Xu, Bo
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supporting information
p. 568 - 573
(2021/02/06)
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- Polyphosphoric acid-promoted synthesis of coumarins lacking substituents at positions 3 and 4
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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.
- Yang, Li-Shou,Wang, Yu,Wang, En-Hua,Yang, Jan,Pan, Xiong,Liao, Xiu,Yang, Xiao-Sheng
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supporting information
p. 1 - 6
(2020/07/25)
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- Synthesis method of coumarin derivatives
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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.
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Paragraph 0054-0056
(2020/09/23)
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- Generation of Alkyl Radical through Direct Excitation of Boracene-Based Alkylborate
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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.
- Hashizume, Daisuke,Hosoya, Takamitsu,Nakamura, Kei,Ohmiya, Hirohisa,Sato, Yukiya,Sumida, Yuto
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supporting information
p. 9938 - 9943
(2020/06/27)
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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 0104; 0105
(2017/01/12)
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- Rh-Catalyzed Synthesis of Coumarin Derivatives from Phenolic Acetates and Acrylates via C-H Bond Activation
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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.
- Gadakh, Sunita K.,Dey, Soumen,Sudalai, Arumugam
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p. 11544 - 11550
(2015/12/04)
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- Manganese(III)-mediated direct Csp2-H radical trifluoromethylation of coumarins with sodium trifluoromethanesulfinate
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Mn(OAc)3-mediated direct Csp2-H radical trifluoromethylation of coumarins with CF3SO2Na (Langlois reagent) to afford selective 3-trifluoromethyl coumarins in moderate to good yields is described. This methodology can also be applied to the trifluoromethylation of quinolinones and pyrimidinones. The Royal Society of Chemistry 2014.
- Cao, Xiao-Hui,Pan, Xiangqiang,Zhou, Peng-Jun,Zou, Jian-Ping,Asekun, Olayinka Taiwo
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supporting information
p. 3359 - 3362
(2014/03/21)
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- 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
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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.
- Zhou, Ji,Luo, Yuanyuan,Li, Qiang,Shen, Jiaoning,Wang, Rui,Xu, Yufang,Qian, Xuhong
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supporting information
p. 2770 - 2773
(2014/07/07)
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- Palladium-catalyzed synthesis of benzofurans and coumarins from phenols and olefins
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Triple C-H functionalization: Palladium-catalyzed synthesis of benzofurans and coumarins by reacting phenols and unactivated olefins is described. The reaction comprises sequential C-H functionalization and shows diverse functional group compatibility. Preliminary mechanistic studies shed light into the possible mechanisms. Copyright
- Sharma, Upendra,Naveen, Togati,Maji, Arun,Manna, Srimanta,Maiti, Debabrata
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supporting information
p. 12669 - 12673
(2013/12/04)
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- One-pot catalysis of dehydrogenation of cyclohexanones to phenols and oxidative Heck coupling: Expedient synthesis of coumarins
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One-pot reactions leading to highly functionalized coumarins have been developed via a Pd(ii)-catalyzed dehydrogenation-oxidative Heck-cyclization process.
- Kim, Donghee,Min, Minsik,Hong, Sungwoo
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supporting information
p. 4021 - 4023
(2013/07/26)
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- Tandem aldehyde-alkyne-amine coupling/cycloisomerization: A new synthesis of coumarins
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Cu-catalyzed A3 coupling of ethoxyacetylene, pyrrolidine and salicylaldehydes led to a concomitant cycloisomerization followed by hydrolysis of the resultant vinyl ether to afford coumarins in a cascade process. The reaction proceeded through exclusive 6-endo-dig cyclization and is compatible with halo and keto groups giving coumarins in good to moderate yields.
- Reddy, Maddi Sridhar,Thirupathi, Nuligonda,Haribabu, Madala
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supporting information
p. 180 - 184
(2013/03/14)
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- Reimer-tiemann reaction of coumarins
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Improved yields of aldehydes from the Reimer-Tiemann reaction of coumarin and two of its derivatives, namely 7-methylcoumarin and 3,4-benzocoumarin, are obtained by carrying the reaction in a two-step procedure. Using crown ether as phase transfer catalyst, a further improvement in the yield of products is achieved. Additionally, coumarin and 7- methylcoumarin are shown to give dialdehydes under this condition. Dialdehydes are reported for the first time from the Reimer-Tiemann reaction. Copyright Taylor & Francis Group, LLC.
- Bhunia, Sankar C.,Patra, Gopal C.,Pal, Sudhir C.
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p. 3678 - 3682
(2011/10/09)
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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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- Intramolecular Wittig reactions. A new synthesis of coumarins and 2-quinolones
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o-Hydroxybenzaldehydes (1a-d) on reaction with chloroacetyl chloride in presence of pyridine followed by addition of triphenyl phosphine and base gave coumarins (2a-d). A similar sequence of reactions on o-aminoacetophenone/benzophenone (1e-f) and methyl anthranilate (1g) gave the corresponding 2-quinolones (2e-g).
- Desai, Vidya G.,Shet, Jyoti B.,Tilve, Santosh G.,Mali, Raghao S.
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p. 628 - 629
(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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- The effect of phenyl substituents on the release rates of esterase-sensitive coumarin-based prodrugs
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A coumarin-based prodrug system has been recently developed in our laboratory for the preparation of esterase-sensitive prodrugs of amines, peptides, and peptidomimetics. The drug release rates from this prodrug system were found to be dependent on the structural features of the drug moiety. In certain cases, the release can be undesirably slow for drugs that are secondary amines with relatively high pK(a)'s. Aimed at finding ways to manipulate the release rates to suit the need of different drugs, we have examined the effect of the phenyl ring substitutions on the release kinetics of such prodrugs and found that appropriately positioned alkyl substituents on the phenyl ring could help to facilitate the release by as much as 16-fold. Therefore, introduction of alkyl substituents on the phenyl ring should allow us to manipulate the release rates and, therefore, time profiles for different drugs.
- Liao,Hendrata,Sung Yong Bae,Wang
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p. 1138 - 1147
(2007/10/03)
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- Tandem Wessely oxidation and intramolecular Diels-Alder reactions. III. Synthesis of isotwistanes
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Wessely oxidation of o-(3-alkenyl) phenols (5) with lead tetraacetate gives 6-acetoxy-6-(3-alkenyl)-2,4-cyclohexadien-1-ones (6), which undergo intramolecular Diels-Alder reactions to give isotwistene (hexahydro-1,5-methanoindene) derivatives (7).These, on hydrolysis followed by oxidation with periodic acid, give hexahydro-1-oxo-1H-indene-5-carboxylic acids (41, 46).Compounds 5 were prepared either by Grignard coupling of o-methoxybenzyl chloride with allyl halides followed by de-O-methylation with sodium thioethoxide or via reduction of dihydrocoumarins (18-20) to 2-chromanols (21-23) with diisobutylaluminum hydride, followed by Wittig reaction of these with ethyl (triphenylphosphoranylidene)acetate.
- Yates, Peter,Macas, Tadas S.
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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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