- Synthesis of: Cis / trans -dihydrochromenones via a photoinduced rearrangement of 4-phenyl-3-aryl/cyclohexenylcoumarins
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A concise and environmentally friendly protocol has been developed for the synthesis of cis-dihydrochromenones and trans-dihydrochromenones in EtOH at room temperature. Irradiation of 4-phenyl-3-arylcoumarins in EtOH with 313 nm UV light under an argon atmosphere at room temperature gave cis-4b,15c-dihydro-16H-benzofuro[3′,2′:7,8]phenanthro[9,10-c]chromen-16-ones and cis-8c,14b-dihydro-9H-benzo[11,12]chryseno[5,6-c]chromen-9-ones in good yields. And an analogous treatment of 4-phenyl-3-alkenylcoumarins as 4-phenyl-3-arylcoumarins provided trans-1,2,3,4,4a,14b-hexahydro-5H-phenanthro[9,10-c]chromen-5-ones. The described photorearrangement proceeded smoothly without the addition of any transition metals and additives. The photorearrangement of 4-phenyl-3-arylcoumarins is believed to proceed via 6π-electrocyclization, a [1,3]-hydrogen shift and keto-enol isomerization.
- Gao, Wangxi,Liang, Yong,Niu, Lixin,Wang, Ding,Wang, Tao,Zhang, Zunting
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- Highly efficient construction of bisspirooxindoles containing vicinal spirocenters through an organocatalytic modified Feist-Bénary reaction
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We have developed an organocatalytic modified Feist-Bénary reaction of cyclic dicarbonyl compounds, isatins and cyclic α-bromo dicarbonyl compounds. This method affords bisspirooxindole-fused dihydrofurans containing two vicinal spiro centers. To the best
- Ahadi, Somayeh,Khavasi, Hamid Reza,Bazgir, Ayoob
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- Synthesis of antimicrobial 2,9,10-trisubstituted-6-oxo-7,12-dihydro-chromeno[3,4-b]quinoxalines
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A new series of 2,9,10-trisubstituted-6-oxo-7,12-dihydro-chromeno[3,4-b]quinoxalines was synthesized and submitted to antibacterial and antifungal activities. Result of the antimicrobial screening showed the compound 4j being the most effective among the various treatments in antimicrobial screening. Compounds 4c, 4d, 4k, and 4l showed moderate activity against the microorganisms tested.
- Kotharkar, Sandeep A.,Shinde, Devanand B.
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- Synthesis of Polycyclic Heteroaromatic Coumarins via Photoinduced Dehydrogenative Annulation of 4-Phenyl-3-heteroarylcoumarins
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An efficient, oxidant and metal-free synthesis of polycyclic heteroaromatic coumarins was developed. H-Furo[2′,3′:3,4]naphtho[2,1-c]chromen-4-one (2a-2f), 1H-benzofuro[2′,3′:3,4]naphtho[2,1-c]chromen-1-one (2g-2j), and 4H-thieno[2′,3′:3,4]naphtho[2,1-c]ch
- Shi, Juan,Kang, Yang,Wang, Tao,Liang, Yong,Zhang, Zunting
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supporting information
p. 13940 - 13948
(2018/11/30)
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- Convenient Michael addition/β-elimination approach to the synthesis of 4-benzyl- and 4-aryl-selenyl coumarins using diselenides as selenium sources
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A concise and efficient, two-step approach toward 4-organoselenyl coumarin derivatives from the easily available 4-hydroxycoumarins, is reported. The synthesis was based on conventional tosylation followed by a tandem selena-Michael addition/β-elimination reaction of an aryl-/benzyl-selenolate anion on the corresponding 4-tosyloxycoumarins. The selenolate anions were conveniently generated in situ by exposure of the corresponding diselenides to NaBH4. Selected compounds demonstrated to exhibit antioxidant properties in mice cortex and hippocampus.
- Padilha, Gustavo,Birmann, Paloma T.,Domingues, Micaela,Kaufman, Teodoro S.,Savegnago, Lucielli,Silveira, Claudio C.
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p. 985 - 990
(2017/02/15)
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- Reaction of 4-hydroxycoumarin or its O-substituted derivatives with diatomic interhalogens: ICl and IBr
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Herein, we present some aspects regarding the iodination/bromination of 4-hydroxycoumarin or its O-methyl or O-acetyl derivatives with iodine monochloride or iodine monobromide as halogenation reagents. Also, the investigation of photochemical transformation of the three 3-iodocoumarins was investigated for the first time.
- Popa, Marcel Mirel,Draghici, Constantin,Barbu, Loredana,Dumitrescu, Denisa E.,Dumitrascu, Florea
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supporting information
p. 344 - 350
(2017/02/10)
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- Pd-catalyzed cross-coupling study of bi-functional 3-bromo-4-trifloxycoumarins with triarylbismuth reagents
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Abstract The cross-coupling reactions of functionalized 3-bromo-4-trifloxycoumarins have been explored with threefold arylating triarylbismuth reagents. These palladium-catalyzed reactions afforded chemo-selective C-4 arylations with the facile formation of 3-bromo-4-arylcoumarins in good to high yields. Additionally, palladium-catalyzed arylations of functionalized 3-bromo-4-arylcoumarins also participated in the second arylation to give functionalized 3,4-diarylcoumarins in high yields.
- Rao, Maddali L.N.,Kumar, Abhijeet
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p. 5137 - 5147
(2015/06/30)
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- An efficient regioselective bromination protocol of activated coumarins using 2,4,4,6-tetrabromo-2,5-cyclohexadienone
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2,4,4,6-Tetrabromo-2,5-cyclohexadienone mediated bromination of a wide assortment of activated coumarins in acetonitrile has been accomplished with high regioselectivity and good to excellent yields. The selectivity and efficiency of bromination were found to be markedly dependent on electronic factors, particularly degree of electron withdrawal from electron-releasing 7-oxygenated substituents to the C-3 position of the α-pyrone moiety by vinylogous resonance and the presence of nucleophilic additives such as water and tetra-n-butylammonium bromide in the reaction medium. The sole by-product of the reaction was converted back to the reagent by oxidation with KBr-KBrO 3, which was recycled three times without significant loss of efficiency.
- Ganguly, Nemai C.,Nayek, Subhasis,Chandra, Sumanta
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supporting information
p. 1155 - 1159
(2013/11/06)
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- Dual-mode fluorescence switching of photochromic bisthiazolylcoumarin
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Three new photochromic coumarins were synthesized. Fluorescence of the open form of 7-hydroxy-3,4-bisthiazolyl-coumarin increased to 1400% by changing the pH only slightly from 6.05 to 7.58. This was subsequently quenched to 1.5% of the maximum intensity at the UV photostationary state in water-methanol media.
- Suzuki, Kazushi,Ubukata, Takashi,Yokoyama, Yasushi
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supporting information; scheme or table
p. 765 - 767
(2012/02/01)
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- Synthesis, antibacterial, and analgesic activity of novel 4-hydroxy-3-(phenylthio)-2H-chromen-2-ones and 4-Hydroxy-3-[imidazol/tetrazolo- 2-yl)thio]-2H-chromen-2-ones
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A mild and efficient synthesis of new 4-hydroxy-3-(phenylthio)-2H-chromen- 2-ones 4a-k and 4-hydroxy-3-[imidazol/tetrazolo-2-yl)thio]-2H-chromen-2-ones 6a-d is described. The compounds 4a-c were further subjected to oxidation by m-CPBA to obtain 3-(phenylsulfonyl)-4-hydroxy-2H-chromen-2-ones 5a-c. The structures of the resulted new compounds were established by IR, 1H NMR, mass, and elemental analysis. All the synthesized compounds were subjected to antibacterial activity against the Gram positive bacteria Staphylococcus aureus, Bacillus subtilis, and Streptococcus haemolytius and the Gram negative bacteria Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia. The analgesic activity was carried out using Swiss albino male mice by abdominal concentration method. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. Copyright Taylor &Francis Group, LLC.
- Rajesha,Mahadevan, Kittappa M.,Satyanarayan,Bhojya Naik
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p. 1733 - 1743
(2011/10/08)
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- One-pot synthesis of furocoumarins via sequential Pd/Cu-catalyzed alkynylation and intramolecular hydroalkoxylation
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A novel and rapid assembly of an interesting class of furocoumarins-4H- furo[3,2-c]chromen-4-ones has been successfully achieved using one-pot sequential coupling/cyclization strategy with easily available starting materials 3-bromo-4-acetoxycoumarins and
- Chen, Lei,Li, Yi,Xu, Ming-Hua
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experimental part
p. 3073 - 3077
(2010/09/06)
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- Bromination of aromatic compounds using ammonium bromide and oxone
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A simple, efficient and mild method for the selective bromination of activated aromatic compounds using ammonium bromide as the source of bromine and Oxone as the oxidant in methanol or water as solvent is reported. The reaction proceeds at ambient temperature in yields ranging from moderate to excellent without a catalyst. Georg Thieme Verlag Stuttgart.
- Arunkumar, MacHarla,Rohitha, Chozhiyath Nappunni,Kulkarni, Shivanand Janardhan,Narender, Nama
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experimental part
p. 1629 - 1632
(2010/06/20)
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- Simple catalyst-free regio- and chemoselective monobromination of aromatics using NBS in polyethylene glycol
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NBS in polyethylene glycol has been efficiently utilized for regio- and chemoselective bromination of activated aromatics at room temperature to form the corresponding bromo products in excellent yields. Copyright Taylor & Francis Group, LLC.
- Venkateswarlu, Katta,Suneel, Kanaparthy,Das, Biswanath,Reddy, Kuravallapalli Nagabhushana,Reddy, Thummala Sreenivasulu
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experimental part
p. 215 - 219
(2009/04/07)
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- General and efficient route for the synthesis of 3,4-disubstituted coumarins via Pd-catalyzed site-selective cross-coupling reactions
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(Chemical Equation Presented) Palladium-catalyzed site-selective cross-coupling reactions of 3-bromo-4-trifloxycoumarin or 3-bromo-4- tosyloxycoumarin provide an efficient and facile route for the synthesis of 3,4-disubstituted coumarins, which include 3,
- Zhang, Liang,Meng, Tianhao,Fan, Renhua,Wu, Jie
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p. 7279 - 7286
(2008/02/11)
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- An efficient, rapid and regioselective nuclear bromination of aromatics and heteroaromatics with NBS using sulfonic-acid-functionalized silica as a heterogeneous recyclable catalyst
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A simple, efficient and rapid method has been developed for high-yielding regioselective nuclear monobromination of aromatic and heteroaromatic compounds using NBS in the presence of sulfonic-acid-functionalized silica at room temperature. The catalyst works under heterogeneous conditions and can be recycled.
- Das, Biswanath,Venkateswarlu, Katta,Krishnaiah, Maddeboina,Holla, Harish
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p. 8693 - 8697
(2007/10/03)
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- Mild regioselective monobromination of activated aromatics and heteroaromatics with N-bromosuccinimide in tetrabutylammonium bromide
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Highly regioselective nuclear bromination of activated aromatic and heteroaromatic compounds has been accomplished using N-bromosuccinimide in tetrabutylammonium bromide. Pre-dominant para-selective monobromination of activated aromatics such as phenols and anilines, rate acceleration of bromination for moderately activated and less reactive substrates on addition of acidic montmorillonite K-10 clay, with or without microwave assistance, are the notable features of this protocol.
- Ganguly, Nemai C.,De, Prithwiraj,Dutta, Sanjoy
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p. 1103 - 1108
(2007/10/03)
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- Reactions of 4-hydroxycoumarin with some α,β-unsaturated carbonyls and 1,3-dicarbonyls: Trapping of 4-hydroxycoumarin tautomers; formation of a pimelic acid derivative and a novel bicyclo compound
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4-Hydroxycoumarin (1) being endowed with both nucleophilic and electrophilic properties furnishes the dimeric coumarin derivative 3 in a pyridine catalyzed self-condensation process; while its attempted morpholine catalyzed self-condensation yields no dimeric coumarin derivative, but leads to the formation of the enamine derivative 2, establishing the existence of the less stable 2,4-chromandione tautomer (1′) of 4-hydroxycoumarin. Pyridine catalyzed condensation between 4-hydroxycoumarin and acrylic acid affords 4-salicyloylpimelic acid (4) via the formation of 3,3-disubstituted-4-hydroxycoumarin and its subsequent hydrolysis and decarboxylation. But the condensation under similar condition with crotonic acid and with mesityl oxide separately leads to the isolation of the pyranocoumarin derivatives 5 and 6, respectively, along with a little amount 3 in either case. However, when β,β-disubstituted-α,β-unsaturated acid like β,β-dimethylacrylic acid, and α,β-unsaturated acids with a bulky β-substitutent like cinnamic, p-chlorocinnamic and 3, 4-methylenedioxycinnamic acids are used, no condensation product excepting the same dimeric coumarin derivative 3 is formed apparently due to the reduced electrophilicity of the β-carbon and steric crowding in the transition state. Condensation of 4-hydroxycoumarin with ethyl acetoacetate produces the α-pyranocoumarin 7, while with acetylacetone leads to the formation of a novel bicyclo compound 8 having two 4-hydroxycoumarin moieties with one acetylacetone moiety bridging them. These condensations using other bases like sodium bicarbonate, piperidine and morpholine afford the same products with varied rates of their formation. Refluxing 4-hydroxycoumarin (1) or its enamine 2 with acetic anhydride in acetic acid gives 3-acetyl-2-hydroxy-4-chromanone (9), stabilized by intramolecular H-bonding and thus indicating the existence of the least stable tautomeric form 1″ (2-hydroxy-4-chromenone) of 4-hydroxycoumarin (1).
- Talapatra, Bani,Mandal, Sudipta Kumar,Biswas, Kallolmay,Chakrabarti, Ramaprasad,Talapatra, Sunil K.
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p. 765 - 771
(2007/10/03)
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- Ylides of Heterocycles, VIII. Reactions of Iodonium-Ylides with Acids
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The reaction of various organic and inorganic acids (HX) with iodonium ylides 2 leads to nucleophilic substitution of the iodobenzene substituent by the anion X(-) to yield the heterocycles 5.Some of them are hydrolyzed to the hydroxy compounds 3 or reduced to the starting compounds 1 under the reaction conditions.Reaction of the iodonium ylide 2b with monomethyl sulfate gives the salt 9, which with bases undergoes nucleophilic substitution to compounds 8 and 10-12, respectively, or is converted to 2b again. - Keywords: 3-Acetoxy-4-hydroxy-2-quinolones; 2-Oxoquinoline-4-olates; 3-Substituted 4-hydroxy-2-quinolones
- Pongratz, Erik,Kappe, Thomas
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p. 231 - 242
(2007/10/02)
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- IODONIUM DERIVATIVES OF β-DICARBONYL COMPOUNDS. XXIII. SYNTHESIS AND PROPERTIES OF IODONIUM DERIVATIVES OF 4-HYDROXYCOUMARIN
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The 3-aryliodonio-4-hydroxycoumarin betaines were obtained by the reaction of 4-hydroxycoumarin with (diacetoxyiodo)benzene and 4-methoxy(diacetoxyiodo)benzene in acetone solution.When heated, they form the products from intramolecular arylation, i.e., 3-
- Adamsone, B. Ya.,Neiland, O. Ya.
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p. 319 - 322
(2007/10/02)
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- A New Sensitive and Selective Photometric Method of Determination of Trace Amount Molybdenum with 4-Hydroxy-Coumarinthiol
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A new photometric method for the determination of molybdenum (VI) with 4-hydroxy-coumarinthiol is reported in this paper.The reagent forms a stable intensely coloured violet complex extracted in chloroform.The complex extracted from 1 M HCl absorbs maximum at 560 nm and has the molar absorptivity 1.2*104 1.mole-1cm-1.The system conforms to Beer's law from 0.5 to 12 ppm with optimum range 1-7 ppm at 560 nm.The Sandell's sensitivity of the reaction is 0.00812 μg cm-2 Mo(VI). 7.5 times excess of Cu(II), V(V), W(VI) is tolerated and all other ions do not interfere.The stepwise and overall stability constants of the 1:2 complex have been determined by spectrophotometric methods.
- Bag, S. P.,Chakrabarti, A. K.,Goswami, J. P.
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p. 901 - 903
(2007/10/02)
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