- Applied photochemistry - Light controlled perfume release
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Ambient light is one of the most suitable available trigger conditions for the release of covalently bound volatile odorants in home- and laundry-care applications. We report on three complementary classes of light-cleavable fragrance precursors, covering the controlled release of odorants with a wide range of functional groups. o-Hydroxy cinnamates 1 undergo a UV-induced double bond isomerization followed by transesterification to release coumarin and a fragrance alcohol of choice. α-Alkoxyacetophenones 10 and α,α-dialkoxyacetophenones 12 undergo Norrish type II fragmentations upon UV-irradiation, thereby releasing one or two equivalents of fragrant aldehydes, respectively. Finally, photoexcited Xanthenoic esters 22 undergo fragmentation to release reactive acyl radicals, which further cyclize onto internal olefins to form perfumery lactones of various ring sizes. Schweizerische Chemische Gesellschaft.
- Derrer, Samuel,Flachsmann, Felix,Plessis, Caroline,Stang, Melanie
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- ACCUMULATION OF COUMARINS IN ELICITOR-TREATED CELL SUSPENSION CULTURES OF AMMI MAJUS
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Heterotrophic cell suspension cultures were initiated from hypocotyls of young Ammi majus L. seedlings.When these cultures were propagated continuously in the dark, they produced only traces of the coumarin umbelliferone.Upon addition of fungal cell wall fractions, i.e. a skleroglucan or an elicitor from either Phytophthora megasperma f. sp. glycinea or Alternaria carthami, the cells excreted large amounts of umbelliferone in addition to isopimpinellin, (S)-marmesin, (R)-ammirin, umbelliferone--ether and umbelliferone--ether.The last two compounds are new compounds and appear to be derived from 7-O-prenylumbelliferone, a coumarin that has been identified in from other plants.The Phytophthora-elicitor was the most effective inducer of coumarin accumulation.When cultures which had been elicited for 3 hr were pulsed with L-14C>phenylalanine for 7 hr, all the coumarins and an additional, still unidentified compound in the extracts were labelled efficiently.Our results suggest that A. majus cells are particularly suitable for biosynthetic studies on various coumarins as well as for regulatory studies of the inhibition of coumarin phytoalexin accumulation.
- Hamerski, Daria,Beier, Ross C.,Kneusel, Richard E.,Matern, Ulrich,Himmelspach, Karl
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- Cu-Catalyzed Phenol O-Methylation with Methylboronic Acid
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A Cu-catalyzed oxidative cross-coupling of phenols with methylboronic acid to form aryl methyl ethers has been developed, expanding the scope of Chan-Evans-Lam alkylation. Electron-deficient phenol derivatives with a broad array of functional groups are methylated in high yields. Increased reaction temperature and catalyst loading enables the methylation of substrates incorporating pyridine and dihydroquinolone motifs. Electron-rich phenol derivatives are poor substrates for the methylation; the characterization of C?H homodimerization products formed from these substrates illuminates a competing mechanistic pathway.
- Bartlett, Mairead E.,Chavez, Angela K.,Gaffney, Uma Bhagwat,Gorin, David J.,Lee, Joyce,Sharew, Betemariam,Wu, Miranda,Zhu, Yingchuan
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supporting information
p. 5661 - 5664
(2021/11/11)
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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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- Trialkylammonium salt degradation: Implications for methylation and cross-coupling
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Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
- Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
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p. 6949 - 6963
(2021/06/02)
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- Gold(I)-Catalyzed Intramolecular Hydroarylation of Phenol-Derived Propiolates and Certain Related Ethers as a Route to Selectively Functionalized Coumarins and 2 H-Chromenes
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Methods are reported for the efficient assembly of a series of phenol-derived propiolates, including the parent system 56, and their Au(I)-catalyzed cyclization (intramolecular hydroarylation) to give the corresponding coumarins (e.g., 1). Simple syntheses of natural products such as ayapin (144) and scoparone (145) have been realized by such means, and the first of these subject to single-crystal X-ray analysis. A related process is described for the conversion of propargyl ethers such as 156 into the isomeric 2H-chromene precocene I (159), a naturally occurring inhibitor of juvenile hormone biosynthesis.
- Cervi, Aymeric,Vo, Yen,Chai, Christina L. L.,Banwell, Martin G.,Lan, Ping,Willis, Anthony C.
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p. 178 - 198
(2020/12/22)
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- Synthesis and biological evaluation of novel coumarin derivatives in rhabdoviral clearance
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Diseases caused by rhabdoviruses have had a huge impact on the productive lives of the entire human population. The main problem is the lack of drugs for the treatment of this family of viruses. Infectious hematopoietic necrosis virus (IHNV), the causative agent of IHN, is a typical rhabdovirus which has caused huge losses to the salmonid industry. Therefore, in this study, IHNV was studied as a model to evaluate the antiviral activity of 35 novel coumarin derivatives. Coumarin A9 was specifically selected for further validation studies upon comparing the half maximum inhibitory concentration (IC50) of four screened candidate derivatives in epithelioma papulosum cyprinid (EPC) cells, as it exhibited an IC50 value of 2.96 μM against IHNV. The data revealed that A9 treatment significantly suppressed the virus-induced cytopathic effect (CPE) in EPC cells. In addition, A9 showed IC50 values of 1.68 and 2.12 μM for two other rhabdoviruses, spring viremia of carp virus and micropterus salmoides rhabdovirus, respectively. Furthermore, our results suggest that A9 exerts antiviral activity, but not by destroying the virus particles and interfering with the adsorption of IHNV. Moreover, we found that A9 had an inhibitory effect on IHNV-induced apoptosis in EPC cells, as reflected by the protection against cell swelling, formation of apoptotic bodies, and loss of cell morphology and nuclear division. There was a 19.05 % reduction in the number of apoptotic cells in the A9 treatment group compared with that in the IHNV group. In addition, enzyme activity assays proved that A9 suppressed the expression of caspase 3, 8 and 9. These results suggested that A9 inhibit viral replication, to some extent, by blocking IHNV-induced apoptosis. In an in vivo study, A9 exhibited an anti-rhabdovirus effect in virus-infected fish by substantially enhancing the survival rate. Consistent with the above results, A9 repressed IHNV gene expression in virus-sensitive tissues (brain, kidney and spleen) in the early stages of virus infection. Importantly, the data showed that horizontal transmission of IHNV was reduced by A9 in a static cohabitation challenge model, especially in fish that underwent bath treatment, suggesting that A9 might be a suitable therapeutic agent for IHNV in aquaculture. Therefore, coumarin derivatives can be developed as antiviral agents against rhabdoviruses.
- Chen, Jiong,Hu, Yang,Liu, Lei,Qiu, Tianxiu,Shan, Lipeng
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supporting information
(2021/08/10)
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- Concise Synthesis of Chromene/Chromane-Type Aryne Precursors and Their Applications
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The gram-scale synthesis of 5,6-, 6,7-, and 7,8-chromene/chromane-type aryne precursors and their applications in regioselective transformation to other functional derivatives is reported. Chromene/chromane-type arynes are generated under mild conditions, which can further undergo [2 + 2], [3 + 2], and [4 + 2] cycloaddition reactions, nucleophilic addition reactions, and σ-insertion reactions to produce structurally novel substituted chromenes and chromanes. The excellent regioselectivity of the reaction is facilitated by the oxygen-containing guiding groups at the ortho-position of the triple bond, which can be removed or switched to other functional groups including alkenyl, aryl, heteroaryl, and arylamino groups.
- Xu, Yuan-Ze,Tian, Jia-Wei,Sha, Feng,Li, Qiong,Wu, Xin-Yan
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p. 6765 - 6779
(2021/05/06)
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- Fe(III)-Catalyzed Decarboxylative C3-Difluoroarylmethylation of Coumarins with α,α-Difluoroarylacetic Acids
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A facile Fe(III)-catalyzed oxidative decarboxylative radical coupling reaction of α,α-difluoroarylacetic acids with coumarins has been developed. This transformation, which provides a series of C-3 difluoroarylmethylated coumarins containing various functional groups in moderate-to-good yields, features easily accessible starting materials and operational simplicity.
- Chen, Zhiwei,Bai, Xiang,Sun, Jie,Xu, Yicheng
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supporting information
p. 7674 - 7682
(2020/07/15)
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- Design, synthesis and biological evaluation of O-alkyl umbelliferone derivatives as pancreatic lipase inhibitors
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A series of coumarin derivatives were synthesised through O-alkylation of umbelliferone. These derivatives were screened for their pancreatic lipase (PL) inhibitory potential. The PL inhibitory effect of compounds with various benzyl and long chain alkyl substituents on umbelliferone were analysed. The compound 1g, having the geranyl substituent was found to have better PL inhibitory potential with an IC50 of 21.64 M. The compounds 1a-j were subjected to molecular docking into the crystal structure of human PL. The molecular docking results are in correlation with the in vitro PL inhibition activity, wherein compound 1g showed a higher MolDock score of -122.12 kcal/mol. The long chain alkyl groups were found to have PL inhibition due to additional interactions with lid domain amino acids (Phe215, Tyr114, Phe77), as revealed by molecular docking study.
- Yadav, Nisha,Auti, Prashant,George, Ginson,Paul, Atish T.
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p. 1265 - 1271
(2020/12/04)
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- Chlorophyll-catalyzed photochemical regioselective coumarin C-H arylation with diazonium salts
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This communication describes the development of a mild method for the cross-coupling of the C3-position of coumarin with an array of diazonium salts mediated by chlorophyll as a biocatalyst via visible light catalysis. A natural pigment such as chlorophyll is used as a green photosensitizer and environmentally benign catalyst. This general and easy procedure provides a transition-metal-free alternative for the formation of 3-aryl coumarin derivatives at room temperature with good to excellent yields. This journal is
- Moazzam, Ali,Jafarpour, Farnaz
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supporting information
p. 16692 - 16696
(2020/10/27)
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- Combined molecular modeling and cholinesterase inhibition studies on some natural and semisynthetic O-alkylcoumarin derivatives
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Coumarins of synthetic or natural origins are an important chemical class exerting diverse pharmacological activities. In the present study, 26 novel O-alkylcoumarin derivatives were synthesized and have been tested at 100 μM for their in vitro inhibitory potential against acetylcholinesterase (AChE) and butyrlcholinesterase (BChE) targets which are the key enzymes playing role in the pathogenesis of Alzheimer's disease. Among the tested coumarins, none of them could inhibit AChE, whereas 12 of them exerted a marked and selective inhibition against BChE as compared to the reference (galanthamine, IC50 = 46.58 ± 0.91 μM). In fact, 10 of the active coumarins showed higher inhibition (IC50 = 7.01 ± 0.28 μM – 43.31 ± 3.63 μM) than that of galanthamine. The most active ones were revealed to be 7-styryloxycoumarin (IC50 = 7.01 ± 0.28 μM) and 7-isopentenyloxy-4-methylcoumarin (IC50 = 8.18 ± 0.74 μM). In addition to the in vitro tests, MetaCore/MetaDrug binary QSAR models and docking simulations were applied to evaluate the active compounds by ligand-based and target-driven approaches. The predicted pharmacokinetic profiles of the compounds suggested that the compounds reveal lipophilic character and permeate blood brain barrier (BBB) and the ADME models predict higher human serum protein binding percentages (>50%) for the compounds. The calculated docking scores indicated that the coumarins showing remarkable BChE inhibition possessed favorable free binding energies in interacting with the ligand-binding domain of the target. Therefore, our results disclose that O-alkylcoumarins are promising selective inhibitors of cholinesterase enzymes, particularly BChE in our case, which definitely deserve further studies.
- Orhan, Ilkay Erdogan,Senol Deniz, F. Sezer,Salmas, Ramin Ekhteiari,Durdagi, Serdar,Epifano, Francesco,Genovese, Salvatore,Fiorito, Serena
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p. 355 - 362
(2018/12/13)
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- Visible-light-induced regioselective alkylation of coumarins via decarboxylative coupling with N-hydroxyphthalimide esters
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An efficient photocatalytic decarboxylative 3-position alkylation of coumarins by using alkyl N-hydroxyphthalimide esters as alkylation reagents has been developed. A variety of NHP esters derived from aliphatic carboxylic acids (primary, secondary, and tertiary) has been proved to be tolerated for this decarboxylation process, affording a broad scope of 3-alkylated coumarin derivatives in moderate to excellent yields. This protocol was highlighted by its mild conditions, readily available starting materials, operational simplicity, and wide functional group tolerance.
- Jin, Can,Yan, Zhiyang,Sun, Bin,Yang, Jin
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supporting information
p. 2064 - 2068
(2019/04/11)
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- Iron-Catalyzed Regioselective Decarboxylative Alkylation of Coumarins and Chromones with Alkyl Diacyl Peroxides
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A facile iron-catalyzed decarboxylative radical coupling of alkyl diacyl peroxides with coumarins or chromones has been developed, affording a highly efficient approach to synthesize a variety of α-alkylated coumarins and β-alkylated chromones. The reaction proceeded smoothly without adding any ligand or additive and provided the corresponding products containing a wide scope of functional groups in moderate to excellent yields. This protocol was highlighted by its high regioselectivity, readily available starting materials, and operational simplicity.
- Jin, Can,Sun, Bin,Xu, Tengwei,Yan, Zhiyang,Zhang, Xun
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supporting information
p. 1585 - 1591
(2019/08/07)
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- Natural and semisynthetic oxyprenylated aromatic compounds as stimulators or inhibitors of melanogenesis
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It has been very recently shown how naturally occurring oxyprenylated coumarins are effective modulators of melanogenesis. In this short communication we wish to generalize the potentialities as skin tanning or whitening agents of a wider panel of natural and semisynthetic aromatic compounds, including coumarins, cinnamic and benzoic acids, cinnamaldehydes, benzaldehyde, and anthraquinone derivatives. A total number of 43 compounds have been tested assaying their capacity to inhibit or stimulate melanin biosynthesis in cultured murine Melan A cells. The wider number of chemicals herein under investigation allowed to depict a detailed structure-activity relationship, as the following: (a) benzoic acid derivatives are slightly pigmenting agent, for which the effect is more pronounced in compounds with longer O-side chains; (b) independently from the type of substitution, cinnamic acids are able to increase melanin biosynthesis, while benzaldehydes are able to decrease it; (c) coumarins with a 3,3-dimethylallyl or shorter skeletons as substituents in position 7 are tanning agents, while coumarins with farnesyloxy groups are whitening ones; (d) double oxyprenylation in position 6 and 7 and 3,3-dimethylallyl or geranyl skeletons have slight depigmenting capacities, while farnesyl skeletons tend to marginally increase the tanning effect; (e) the presence of electron withdrawing groups (acetyl, COOH, and -Cl) and geranyl or farnesyl oxyprenylated chains respectively in positions 3 and 7 of the coumarin nucleus lead to a whitening effect, and finally (f) oxyprenylated anthraquinones have only a weak depigmenting capacity.
- Genovese, Salvatore,Epifano, Francesco,Medina, Philippe de,Caron, Nicolas,Rives, Arnaud,Poirot, Marc,Poirot, Sandrine Silvent,Fiorito, Serena
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p. 181 - 190
(2019/03/23)
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- Synthesis of 7-Azido-3-Formylcoumarin – A Key Precursor in Bioorthogonally Applicable Fluorogenic Dye Synthesis
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Coumarins represent an important group of natural products and a common part of various drugs and fluorescent dyestuffs. Herein, we present the synthesis of a coumarin that can serve as a key starting material in the design and synthesis of bioorthogonally applicable fluorogenic dyes. The synthesis of 7-azido-3-formylcoumarin started from 7-diallylaminocoumarin. This allyl protected aminocoumarin is otherwise hard to obtain by conventional methods but was conveniently accessed in good yields by a sequential, Wittig-reaction–UV isomerization process. This sequential approach was studied in more details and applied for the synthesis of a series of substituted coumarins even in one-pot.
- Pünk?sti, Zoltán,Kele, Péter,Herner, András
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supporting information
p. 1183 - 1188
(2018/03/21)
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- Half-Sandwich Ruthenium Carbene Complexes Link trans-Hydrogenation and gem-Hydrogenation of Internal Alkynes
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The hydrogenation of internal alkynes with [Cp?Ru]-based catalysts is distinguished by an unorthodox stereochemical course in that E-alkenes are formed by trans-delivery of the two H atoms of H2. A combined experimental and computational study now provides a comprehensive mechanistic picture: a metallacyclopropene (??2-vinyl complex) is primarily formed, which either evolves into the E-alkene via a concerted process or reacts to give a half-sandwich ruthenium carbene; in this case, one of the C atoms of the starting alkyne is converted into a methylene group. This transformation represents a formal gem-hydrogenation of a ?€-bond, which has hardly any precedent. The barriers for trans-hydrogenation and gem-hydrogenation are similar: whereas DFT predicts a preference for trans-hydrogenation, CCSD(T) finds gem-hydrogenation slightly more facile. The carbene, once formed, will bind a second H2 molecule and evolve to the desired E-alkene, a positional alkene isomer or the corresponding alkane; this associative pathway explains why double bond isomerization and over-reduction compete with trans-hydrogenation. The computed scenario concurs with para-hydrogen-induced polarization transfer (PHIP) NMR data, which confirm direct trans-delivery of H2, the formation of carbene intermediates by gem-hydrogenation, and their evolution into product and side products alike. Propargylic aOR (R = H, Me) groups exert a strong directing and stabilizing effect, such that several carbene intermediates could be isolated and characterized by X-ray diffraction. The gathered information spurred significant preparative advances: specifically, highly selective trans-hydrogenations of propargylic alcohols are reported, which are compatible with many other reducible functional groups. Moreover, the ability to generate metal carbenes by gem-hydrogenation paved the way for noncanonical hydrogenative cyclopropanations, ring expansions, and cycloadditions.
- Guthertz, Alexandre,Leutzsch, Markus,Wolf, Lawrence M.,Gupta, Puneet,Rummelt, Stephan M.,Goddard, Richard,Farès, Christophe,Thiel, Walter,Fürstner, Alois
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supporting information
p. 3156 - 3169
(2018/03/08)
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- Peroxy mediated Csp2-Csp3 dehydrogenative coupling: Regioselective functionalization of coumarins and coumarin-3-carboxylic acids
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A regioselective direct alkylation of coumarins at C-3 via cross-dehydrogenative coupling of unactivated Csp2-Csp3 bonds is developed. This protocol employs tert-butyl hydroperoxide as the sole reagent of the reaction to combine coumarins and ethers in reasonable yields under metal- and solvent-free reaction conditions. This protocol also worked well with coumarin-3-carboxylic acids to unveil a rare instance of a catalyst-free tandem alkylation/decarboxylation reaction with conservation of the double bond.
- Jafarpour, Farnaz,Darvishmolla, Masoumeh
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supporting information
p. 3396 - 3401
(2018/05/23)
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- 3-Trifluoromethylated Coumarins and Carbostyrils by Radical Trifluoromethylation of ortho-Functionalized Cinnamic Esters
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A method for the trifluoromethylation of ortho-hydroxycinnamic esters was developed to achieve the regioselective synthesis of 3-trifluoromethylated coumarins. The reaction was performed by using the Togni reagent as the CF3source under mild conditions and showed good functional- group tolerance. The scope of this copper-mediated method was further expanded to the synthesis of 3-trifluoromethylated carbostyrils starting from ortho-aminocinnamic derivatives. Interestingly, a sequential one-pot synthesis of 3-trifluoromethylated coumarins starting from salicylaldehydes was further developed. The mechanism of this cascade reaction was explored, and a radical pathway was found to be consistent with the obtained results.
- Chaabouni, Slim,Simonet, Florent,Fran?ois, Alison,Abid, Souhir,Galaup, Chantal,Chassaing, Stefan
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p. 271 - 277
(2017/01/24)
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- The first total synthesis of anemarchalconyn and anemarcoumarin A
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Anemarchalconyn (1) and anemarcoumarin A (2), the natural bioactive compounds isolated from the rhizomes of Anemarrhena asphodeloides Bunge (Liliaceae), were first totally synthesized using easily available materials in short, convenient routes with overall yields of 32 and 48%.
- Zhang, Jing-Xia,Li, Zhe-Yu,Wang, Yu-Chi,Ma, Wen-Bo,Hou, Ming,Cao, Sheng-Hua,Tang, Ke-Hui,Dong, Hong-Bo
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p. 903 - 909
(2017/08/22)
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- Interaction of 7-Alkoxycoumarins with the Aryl Hydrocarbon Receptor
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The aryl hydrocarbon receptor (AhR) is a transcription factor activated by a vast array of natural and synthetic ligands. It plays a pivotal role in numerous physiological and pathological responses, such as cell proliferation and differentiation, induction of xenobiotic metabolizing enzymes, response to environmental toxins, and several others. In this study, we investigated the ability of some natural compounds (oxyprenylated ferulic acid and umbelliferone derivatives) and their semisynthetic analogues (e.g., differently substituted 7-Alkoxycoumarins) to activate AhR, using a reporter luciferase assay. Among them, we found that 7-isopentenyloxycoumarin was the best AhR activator. Boropinic acid, 7-but-2′-enyloxycoumarin, 7-(2′,2′-dimethyl-n-propyloxy)coumarin, 7-benzyloxycoumarin, and 7-(3′-hydroxymethyl-3′-methylallyloxy)coumarin were also active, although to a lesser extent. All the compounds were also analyzed for their ability to inhibit AhR activation, using a reference ligand, 6-formylindolo[3,2-b]carbazole. Data recorded in the present investigation pointed out the importance of a 3,3-dimethylallyloxy side chain attached to the coumarin ring core as a key moiety for AhR activation.
- Gargaro, Marco,Epifano, Francesco,Fiorito, Serena,Taddeo, Vito Alessandro,Genovese, Salvatore,Pirro, Matteo,Turco, Antonella,Puccetti, Paolo,Schmidt-Weber, Carsten B.,Fallarino, Francesca
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p. 1939 - 1943
(2017/06/28)
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- Microwave-Assisted Synthesis of Phenylpropanoids and Coumarins: Total Synthesis of Osthol
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Herein we describe a one-pot microwave-assisted method for the synthesis of cinnamic acid and coumarin derivatives. The synthesis begins with an aldehyde synthon, and the chosen reaction conditions determine whether a cinnamic acid or coumarin derivative is formed. A regioselective Claisen rearrangement was also efficiently incorporated into the synthetic sequence to further increase the complexity of the product. Notably, this approach provides high product yields and selectivities without the need of a phenol protecting group.
- Konrádová, Daniela,Kozubíková, Hana,Dole?al, Karel,Pospí?il, Ji?í
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supporting information
p. 5204 - 5213
(2017/09/29)
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- Dual functional small molecule fluorescent probes for image-guided estrogen receptor-specific targeting coupled potent antiproliferative potency for breast cancer therapy
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A strategy by integrating biological imaging into early stages of the drug discovery process can improve our understanding of drug activity during preclinical and clinical study. In this article, we designed and synthesized coumarin-based nonsteroidal type fluorescence ligands for drug-target binding imaging. Among these synthesized compounds, 3e, 3f and 3h showed potent ER binding affinity and 3e (IC50?=?0.012?μM) exhibited excellent ERα antagonistic activity, its antiproliferative potency in breast cancer MCF-7 cells is equipotent to the approved drug tamoxifen. The fluorescence of compounds 3e and 3f depended on the solvent properties and showed significant changes when mixed with ERα or ERβ in vitro. Furthermore, target molecule 3e could cross the cell membrane, localize and image drug-target interaction in real time without cell washing. Thus, the coumarin-based platform represents a promising new ER-targeted delivery vehicle with potential imaging and therapeutic properties.
- Yang, Lu,Hu, Zhiye,Luo, Junjie,Tang, Chu,Zhang, Silong,Ning, Wentao,Dong, Chune,Huang, Jian,Liu, Xianjun,Zhou, Hai-Bing
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supporting information
p. 3531 - 3539
(2017/05/29)
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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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- Rational design of a highly selective fluorescent sensor for l-histidine detection in aqueous solution
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Computational studies in combination with experimental research were used to design a new rapid, selective and sensitive "turn-on" fluorescent sensor (H3) for l-histidine, which can be first quenched by Ni2+ and then recovered upon addition of His.
- Qiao, Yan,Chen, Bin,Yang, Yangyang,Wang, Xin,Xu, Yufang,Li, Honglin
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p. 1310 - 1314
(2016/02/03)
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- One Photocatalyst, n Activation Modes Strategy for Cascade Catalysis: Emulating Coumarin Biosynthesis with (-)-Riboflavin
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Generating molecular complexity using a single catalyst, where the requisite activation modes are sequentially exploited as the reaction proceeds, is an attractive guiding principle in synthesis. This requires that each substrate transposition exposes a catalyst activation mode (AM) to which all preceding or future intermediates are resistant. While this concept is exemplified by MacMillan's beautiful merger of enamine and iminium ion activation, examples in other fields of contemporary catalysis remain elusive. Herein, we extend this tactic to organic photochemistry. By harnessing the two discrete photochemical activation modes of (-)-riboflavin, it is possible to sequentially induce isomerization and cyclization by energy transfer (ET) and single-electron transfer (SET) activation pathways, respectively. This catalytic approach has been utilized to emulate the coumarin biosynthesis pathway, which features a key photochemical E → Z isomerization step. Since the ensuing SET-based cyclization eliminates the need for a prefunctionalized aryl ring, this constitutes a novel disconnection of a pharmaceutically important scaffold.
- Metternich, Jan B.,Gilmour, Ryan
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supporting information
p. 1040 - 1045
(2016/02/05)
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- Total synthesis of 8-(6″-umbelliferyl)-apigenin and its analogs as anti-diabetic reagents
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The naturally occurring flavone 8-(6″-umbelliferyl)apigenin, a hybrid structure of apigenin and coumarin, as well as seven of its analogues were synthesized for the first time by using iodination and Suzuki coupling reactions as key steps. The synthesis of 8-(6″-umbelliferyl)-apigenin was achieved in seven linear steps from the commercially available 1-(2,4,6-trihydroxyphenyl)ethan-1-one and 7-hydroxyl coumarine with 31% overall yield. Effects of these compounds on glucose disposal were investigated in adipocytes. All of the flavonoid and coumarin hydrids were found to have better bioactivities than their corresponding flavonoid cores. The most potent compound 15 (10?μΜ) could promote glucose consumption by 57% which exhibited similar effect as the positive control metformin at 1?mM. Moreover, fluorescence microscopy showed that four 8-(6″-umbelliferyl)apigenin analogues 2, 15, 30 and 31 could promote the 2-NBDG uptake into 3T3-L1 cells, which consist with those observed in the regulation of glucose.
- Pan, Guojun,Zhao, Lianbo,Xiao, Na,Yang, Ke,Ma, Yantao,Zhao, Xia,Fan, Zhenchuan,Zhang, Yongmin,Yao, Qingwei,Lu, Kui,Yu, Peng
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p. 674 - 683
(2016/07/21)
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- A chinese wonderful ester derivatives and their preparation and use
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The invention belongs to the field of heterocyclic ring organic compounds, and provides a hantzsch ester derivative with the structure formula in formula I shown in the specification. The invention also provides application of the hantzsch ester derivative as an NO fluorescent probe. According to the technical scheme disclosed by the invention, the specificity effects of the hantzsch ester derivative and NO are utilized to generate characteristics of a corresponding pyridine derivative so as to achieve the response to NO of the fluorescent probe. The NO is detected through the change of the fluorescent characteristics before and after the detection effect. The method is simple and controllable, and the probe is high in sensitivity.
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Paragraph 0048-0048
(2017/03/08)
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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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- Cp?Co(III)-Catalyzed Annulations of 2-Alkenylphenols with CO: Mild Access to Coumarin Derivatives
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Cp?Co(III)-catalyzed annulations of 2-alkenylphenols with CO for the synthesis of coumarin derivatives have been developed. The reaction features mild reaction conditions, broad substrate scope, and good functional group tolerance. Preliminary mechanistic studies were conducted, suggesting that C-H activation is the turnover limiting step. Furthermore, the efficiency of this reaction was demonstrated by the rapid total synthesis of three natural products herniarin, xanthyletin, and seselin.
- Liu, Xu-Ge,Zhang, Shang-Shi,Jiang, Chun-Yong,Wu, Jia-Qiang,Li, Qingjiang,Wang, Honggen
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supporting information
p. 5404 - 5407
(2015/11/18)
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- N-Methylimidazole-mediated synthesis of aryl alkyl ethers under microwave irradiation and solvent free conditions
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A microwave-assisted three-component reaction was established for the synthesis of aryl alkyl ethers. The reaction was performed under solvent-free conditions in the presence of N-methylimidazole and dialkyl acetylene-dicarboxylate to furnish a novel approach to O-alkylation of phenol derivatives in high yield.
- Djahaniani, Hoorieh,Aghadadashi-Abhari, Laila,Mohtat, Bita
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p. 459 - 464
(2015/06/16)
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- A new highly selective and sensitive fluorescent probe for Zn2+ and its application in cell-imaging
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A new fluorescent probe, 3-((4-([2,2′:6′,2″-terpyridin]- 4′-yl)phenyl)ethynyl)-7-methoxy-2H-chromen-2-one (ZC-F7) composed of coumarin as the fluorophore and terpyridine as the receptor is designed and synthesized. Based on the intramolecular charge transfer (ICT) effect, the probe exhibits significant variation on emission wavelengths with shifts more than 100 nm after combined with Zn2+, in accordance with the conversion of emission colors from blue to green. Good selectivity and sensitivity of this probe towards Zn2+ can be found even on the ppb level in aqueous solution. The Job's plot test suggests a 1:1 stoichiometry between ZC-F7 and Zn2+. The application of the fluorescence probe in bio-imaging is also demonstrated, proving its potential usage in fields such as environment protection, water treatment and safety inspection.
- Hu, Quan,Tan, Yiqun,Liu, Min,Yu, Jiancan,Cui, Yuanjing,Yang, Yu
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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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- Reduction of substituted phenyl 2-chloroacetates at silver cathodes: Electrosynthesis of coumarins
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To explore the electrosynthesis of coumarins, cyclic voltammetry and controlled-potential (bulk) electrolysis have been employed to investigate the reduction of the carbon-chlorine bond of five substituted phenyl 2-chloroacetates at silver cathodes in dimethylformamide (DMF) containing 0.10 M tetra-n-butylammonium tetrafluoroborate (TBABF4) as supporting electrolyte; the five substrates are 2-formylphenyl 2-chloroacetate (1a), 2-acetylphenyl 2-chloroacetate (2a), methyl 2-(2-chloroacetoxy)benzoate (3a), 2-formyl-5-methoxyphenyl 2-chloroacetate (4a), and 2-formyl-3,5-dimethoxyphenyl 2-chloroacetate (5a). We have examined (a) the effects of substituents on the benzene ring of the substrate as well as the nature of the aryl carbonyl moiety on the formation of the coumarin product and (b) the effect of solvent - namely, DMF, acetonitrile (CH3CN), benzonitrile (PhCN), and propylene carbonate (PC) - and substrate concentration on the yield of the coumarin. It was found that the most unsubstituted substrate (1a) afforded the highest yield (41%) of the desired coumarin in a DMF-TBABF4 medium. A mechanistic scheme is proposed to account for the formation of the coumarin. Furthermore, the only other products seen in these reductions are 2-substituted phenols, which are precursors for synthesis of the various substrates.
- Pasciak, Erick M.,Peters, Dennis G.
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p. G98 - G102
(2015/04/14)
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- Semisynthesis, ex vivo evaluation, and SAR studies of coumarin derivatives as potential antiasthmatic drugs
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Asthma is a chronic inflammatory disorder that causes contraction in the smooth muscle of the airway and blocking of airflow. Reversal the contractile process is a strategy for the search of new drugs that could be used for the treatment of asthma. This work reports the semisynthesis, ex vivo relaxing evaluation and SAR studies of a series of 18 coumarins. The results pointed that the ether derivatives 1-3, 7-9 and 13-15 showed the best activity (E max = 100%), where compound 2 (42 μM) was the most potent, being 4-times more active than theophylline (positive control). The ether homologation (methyl, ethyl and propyl) in position 7 or positions 6 and 7 of coumarins lead to relaxing effect, meanwhile formation of esters generated less active compounds than ethers. The SAR analysis showed that it is necessary the presence of two small ether groups and the methyl group at position 4 (site 3) encourage biological activity through soft hydrophobic changes in the molecule, without drastically affecting the cLogP.
- Sánchez-Recillas, Amanda,Navarrete-Vázquez, Gabriel,Hidalgo-Figueroa, Sergio,Rios, María Yolanda,Ibarra-Barajas, Maximiliano,Estrada-Soto, Samuel
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p. 400 - 408
(2014/04/17)
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- Enzyme-catalyzed conversion of chemical structures on the surface of gold nanorods
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For developing metal nanoparticles of which surface chemical structures could be altered by enzymes in the cells, functional linkers caged by coumaric acids have been synthesized. Synthesized gold nanorod (GNR) conjugates possessing coumaric acid precursors underwent (porcine liver) esterase-catalyzed hydrolysis on their surface to afford GNRs coated with amino-functionalized polyethylene glycol and fluorescent coumarins as reporter molecules for monitoring the conversion. The chemical structural conversion on the GNR surfaces was successfully observed inside cells by fluorescence microscopy when GNR conjugates were incubated with tumor cells.
- Kusaka, Eriko,Ito, Takeo,Tanabe, Kazuhito,Nishimoto, Sei-Ichi
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p. 1435 - 1444
(2013/10/01)
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- Amine-catalyzed cascade synthesis of 3,4-diunsubstituted coumarins
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We disclose an efficient route to synthesize 3,4-diunsubstituted coumarins through a cascade organocatalytic reaction. The reaction is catalyzed by using of a combination of benzylamine (10 mol-%) and triethylamine (10 mol-%). Various salicylaldehydes were tested, and the corresponding coumarin products were obtained in good to high yields under mild and metal-free reaction conditions. We disclose an efficient route to synthesize 3,4-diunsubstituted coumarins through a cascade organocatalytic reaction. The reaction is catalyzed by using of a combination of benzylamine (10 mol-%) and triethylamine (10 mol-%). Various salicylaldehydes are tested, and the corresponding coumarin products are obtained in good to high yields under mild and metal-free reaction conditions. Copyright
- Wei, Jia,Wang, Pengcheng,Jia, Qianfa,Huang, Jiaoyao,Du, Zhiyun,Zhang, Kun,Wang, Jian
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supporting information
p. 4499 - 4502
(2013/07/26)
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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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- Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach
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(E)-Alkyl ortho-hydroxycinnamates cyclize to coumarins at elevated temperatures of 140-250 °C. We find that the use of tri-nbutylphosphane (20 mol %) as a nucleophilic organocatalyst in MeOH solution allows cyclization to take place under much milder conditions (60-70 °C). Several coumarins were prepared, starting from ortho-hydroxyarylaldehydes, by Wittig reaction with Ph3P=CHCO2Me to (E)-methyl ortho-hydroxycinnamates, followed by the phosphane catalyzed cyclization.
- Boeck, Florian,Blazejak, Max,Anneser, Markus R.,Hintermann, Lukas
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supporting information
p. 1630 - 1636,7
(2020/09/14)
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- Synthesis and anthelmintic activity of osthol analogs against Dactylogyrus intermedius in goldfish
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In an attempt to develop novel anthelmintic agents, our previously isolated osthol was used as lead structures for further optimization. In our research, a series of coumarin analogs, prepared from 7-hydroxy coumarin or 7-hydroxy-4-methyl coumarin, have been evaluated for their anthelmintic activities. In all of the compounds, 6 and 7 were first synthesized, and their structures were identified based on NMR and MS values. Among the candidates, 8-allyl-7-allyloxycoumarin showed better anthelmintic activity than other compounds against Dactylogyrus infestation with EC50 value of 1.81 mg/L. The quantitative structure-activity relationship (QSAR) of 16 osthol analogs with anthelmintic activity expressed as pEC50 and toxicity to goldfish expressed pLC50, such results can offer useful theoretical references for future experimental works.
- Liu, Guang-Lu,Hao, Bing,Liu, Shao-Peng,Wang, Gao-Xue
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p. 582 - 590
(2012/09/11)
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- 3-arylcoumarin derivatives manifest anti-proliferative activity through Hsp90 inhibition
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The potential therapeutic benefits associated with Hsp90 modulation for the treatment of cancer and neurodegenerative diseases highlight the importance of identifying novel Hsp90 scaffolds. KU-398, a novobiocin analogue, and silybin were recently identified as new Hsp90 inhibitors. Consequently, a library of 3-arylcoumarin derivatives that incorporated the structural features of KU-398 and silybin was designed, synthesized, and evaluated against two breast cancer cell lines. Western blot analysis confirmed that the resulting 3-arylcoumarin hybrids target the Hsp90 protein folding machinery.
- Zhao, Huiping,Yan, Bin,Peterson, Laura B.,Blagg, Brian S. J.
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supporting information; experimental part
p. 327 - 331
(2012/05/20)
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- Lamellarins as inhibitors of P-glycoprotein-mediated multidrug resistance in a human colon cancer cell line
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Chemical analysis of a Didemnum sp. (CMB-01656) collected during scientific Scuba operations off Wasp Island, New South Wales, yielded five new lamellarins A1 (1), A2 (2), A3 (3), A4 (4) and A5 (5) and eight known lamellarins C (6), E (7), K (8), M (9), S (10), T (11), X (12) and χ (13). Analysis of a second Didemnum sp. (CMB-02127) collected during scientific trawling operations along the Northern Rottnest Shelf, Western Australia, yielded the new lamellarin A6 (14) and two known lamellarins G (15) and Z (16). Structures were assigned to 1-16 on the basis of detailed spectroscopic analysis with comparison to literature data and authentic samples. Access to this unique library of natural lamellarins (1-16) provided a rare opportunity for structure-activity relationship (SAR) investigations, probing interactions between lamellarins and the ABC transporter efflux pump P-glycoprotein (P-gp) with a view to reversing multidrug resistance in a human colon cancer cell line (SW620 Ad300). These SAR studies, which were expanded to include the permethylated lamellarin derivative (17) and a series of lamellarin-inspired synthetic coumarins (19-24) and isoquinolines (25-26), successfully revealed 17 as a promising new non-cytotoxic P-gp inhibitor pharmacophore. Copyright
- Plisson, Fabien,Huang, Xiao-Cong,Zhang, Hua,Khalil, Zeinab,Capon, Robert J.
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supporting information; experimental part
p. 1616 - 1623
(2012/09/08)
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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 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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- A single precatalyst tandem RCM-allylic oxidation sequence
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Ring closing metathesis of allyloxy styrenes and a subsequent Ru-catalyzed allylic oxidation can be combined to a tandem sequence that makes coumarins accessible using less active but more conveniently available first generation catalysts.
- Schmidt, Bernd,Krehl, Stefan
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supporting information; experimental part
p. 5879 - 5881
(2011/06/23)
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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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- Synthesis and biological evaluation of (6- and 7-Phenyl) coumarin derivatives as selective nonsteroidal inhibitors of 17β-hydroxysteroid dehydrogenase type 1
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17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) is an enzyme that catalyzes NADPH-dependent reduction of the weak estrogen, estrone, into the most potent estrogen, estradiol, which exerts proliferative effects via the estrogen receptors. Overexpression of 17β-HSD1 in estrogen-responsive tissues is related to the development of hormone-dependent diseases, such as breast cancer and endometriosis; thus, 17β-HSD1 represents an attractive target for the development of new therapies. We have discovered that simple coumarines 1 and 2 significantly inhibit 17β-HSD1 in a recombinant enzyme assay, with high selectivity against 17β-HSD2. We postulated that the introduction of various p-substituted phenyl moieties to position 6 or 7 of the coumarin core using the Suzuki-Miyaura cross-coupling reaction would provide mimetics of steroidal structures with improved inhibition of 17β-HSD1. The best inhibitor in the series proved to be 6a, with an IC50 of 270 nM, and with exceptional selectivity for 17β-HSD1 over 17β-HSD2 and against the α and β estrogen receptors.
- Star?evi?, ?tefan,Bro?i?, Petra,Turk, Samo,Cesar, Jo?ko,Lani?nik Ri?ner, Tea,Gobec, Stanislav
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experimental part
p. 248 - 261
(2011/03/22)
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- A simple synthesis of functionalized 3-bromocoumarins by a one-pot three-component reaction
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Functionalized 3-bromocoumarins 2 have been, prepared, by a simple one-pot bromination/Wittig/cyclization tandem process from methyl (triphenylphosphoranylidene)acetate, Nbromosuccinimide and a series of 2-hydroxybenzaldehydes. Owing to the commercial availability of salicylaldehyde derivatives, this approach offers such a diverse range of compounds that it fulfills the recent demand for the generation of large combinatorial chemical libraries based on the coumarin scaffold
- Audisio, Davide,Messaoudi, Samir,Brion, Jean-Daniel,Alami, Mouad
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experimental part
p. 1046 - 1051
(2010/04/25)
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- Facile and efficient synthesis of simple coumarins via the Pd(II)/KHC03 catalyzed heck reaction under MW-Assisted neat conditions
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An efficient and fast Pd(II)-catalyzed cross-coupling of aryl halides with olefins has been developed. In the presence of Pd(OAc)2 and PdCI 2 cross-coupling of various aryl halides with olefins underwent smoothly to afford the corresponding products in moderate to high yields under MW mediated neat conditions. Simple coumarins were synthesized in good yields using 2-halophenoles in this procedure. Furthermore no solvent, solid support, expensive or/and toxic ligand is required.
- Valizadeh, Hassan,Vaghefi, Sevil
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experimental part
p. 113 - 120
(2011/06/25)
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- Photoconversion of o-hydroxycinnamates to coumarins and its application to fluorescence imaging
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(E)-o-Hydroxycinnamates were synthesized and their photochemical behavior was investigated in liquid and solid states. It was confirmed by 1H NMR spectroscopy that the (E)-o-hydroxycinnamates converted into the corresponding coumarins via (Z)-o-hydroxycinnamate intermediates. The photoconversion was greatly accelerated in the presence of p-toluenesulfonic acid. The optical properties of the cinnamates were compared with those of the corresponding coumarins. Fluorescence imaging was successfully accomplished by photoirradiation of PMMA films containing the cinnamates.
- Cho, Sung-Youl,Song, Young-Kyu,Kim, Joong-Gon,Oh, Se-Young,Chung, Chan-Moon
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supporting information; experimental part
p. 4769 - 4772
(2011/03/19)
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- Task-specific ionic liquid as reagent and reaction medium for the one-pot Horner-Wadsworth-Emmons-type reaction under microwave irradiation
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A task-specific imidazolium-based phosphinite ionic liquid (IL-OPPh2) was used as the dual solvent-reagent for the synthesis of E-cinamates and coumarin derivatives via the one-pot Horner-Wadsworth-Emmons-type reaction. The ionic liquid containing its cor
- Valizadeh, Hassan,Shockravi, Abbas
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experimental part
p. 4341 - 4349
(2010/04/26)
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