- Divergent synthesis of flavones and aurones via base-controlled regioselective palladium catalyzed carbonylative cyclization
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A regioselective approach for construction of 5-membered and 6-membered flavonoid is established by Pd catalyzed carbonylative cyclization of 2-iodophenol with terminal alkynes using different amine bases under mild reaction condition. The catalytic experiments found that piperazine preferentially accelerate 6-endo cyclization, and triethylamine mediated Pd catalyzed 5-exo cyclization. Under optimized reaction condition, Pd catalyzed carbonylative protocol successfully applied for the diverse structures of 39 examples in good to excellent yield and regioselectivity.
- Xu, Shan,Sun, Huaming,Zhuang, Mengyuan,Zheng, Shaohua,Jian, Yajun,Zhang, Weiqiang,Gao, Ziwei
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p. 264 - 270
(2018/05/04)
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- An efficient oxidative conversion of 2-aryl-2H-chromenes to the corresponding flavones by tert-butylhydroperoxide and copper bromide
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A simple and efficient method has been developed for the facile oxidation of chromenes to the corresponding flavones by tert-butylhydroperoxide (TBHP) in the presence of copper(II) bromide catalyst in toluene at 80 °C in a very short time. The reaction demonstrates excellent reactivity, functional group tolerance, and good to excellent yields without using conventional strong oxidizing agents.
- Banerjee, Dipanwita,Kayal, Utpal,Maiti, Gourhari
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p. 1667 - 1671
(2016/04/04)
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- Iodine catalyzed cascade synthesis of flavone derivatives from 2'-allyloxy-α,β-dibromochalcones
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Synthesis of flavones from 2'-allyloxy-α, β-dibromochalcones has been described. The iodine induced oxidative cyclization of 2'-allyloxy-α, β-dibromochalcones results into the formation of 3-bromoflavanones which ultimately gives flavones. Dehydrobromination of 3-bromoflavanone to give flavone is the preferred reaction over dehydrogenation.
- Nawghare, Beena R.,Gaikwad, Sunil V.,Raheem, Abdul,Lokhande, Pradeep D.
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p. 2284 - 2286
(2014/07/22)
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- Ecofriendly bromination of chalcones and synthesis of flavones using grinding technique
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Selective bromination of chalcones and 2'-hydroxychalcones has been carried out with ammonium bromide and ammonium persulphate using grinding technique at RT under aqueous moist condition to give α,β-dibromochalcones and α,β-dibromo-2'- hydroxychalcones respectively. α,β- Dibromo-2'-hydroxychalcones have been cyclodehydrobrominated with barium hydroxide moist and ethanol at RT to give flavones using grinding technique.
- Jakhar, Komal,Makrandi
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p. 141 - 145
(2013/02/23)
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- Synthesis and biological activities of some flavones
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Chalcones are synthesized by a base catalyzed Claisen Schmidt condensation reaction and then treated with dimethylsulphoxide in presence of iodine to get flavones. The synthesized compounds were evaluated for their antibacterial activity against Escherichia coilt P. aeruginosa, S. epidermidis and B. subtilis. All the flavones showed moderate to good activity. The structures of these compounds were confirmed by IR, UV, 1H NMR, Mass and elemental analysis.
- Sawant,Gill,Nirwan
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- Synthesis and biological activities of some flavones
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Chalcones are synthesized by a base catalyzed Claisen Schmidt condensation reaction and then treated with dimethylsulphoxide in presence of iodine to get flavones. The synthesized compounds were evaluated for their antibacterial activity against Escherichia coli, P. aeruginosa, S. epidermidis and B. subtilis. All the flavones showed moderate to good activity. The structures of these compounds were confirmed by IR, UV, 1H NMR, Mass and elemental analysis.
- Sawant,Gill,Nirwan
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p. 297 - 300
(2013/09/24)
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- An efficient synthesis of 3-bromoflavones under solvent free conditions using grinding technique
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Selective bromination of 1-(2-hydroxyphenyl)-3-phenylpropane- 1,3-diones has been carried out with ammonium bromide and ammonium persulphate at room temperature using grinding technique under solvent free conditions to give 2-bromo derivatives which on cyclodehydration with p-toluenesulphonic acid under grinding conditions give 3-bromoflavones. Also, flavones on bromination using above mentioned conditions give 3-bromoflavones directly.
- Jakhar, Komal,Makrandi
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experimental part
p. 770 - 773
(2012/06/30)
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- Oxidative cyclisation of 2′-hydroxychalcones using sodium tellurite: Synthesis of flavones
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A simple and very efficient method for the oxidative cyclisation of 2′-hydroxychalcones with sodium tellurite in dimethylsulphoxide has been developed which could provide a simple route for the synthesis of flavones and also the required compound obtained as the sole product in a very high yield.
- Kumar, Surender,Sharma, Dinesh
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experimental part
p. 761 - 763
(2012/04/04)
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- Use of Flavone Compounds as Potassium Channel Inhibitors
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This invention provides a method for treating or preventing human atrial arrhythmia (fibrillation) using the leading flavone compound acacetin, and its derivatives and analogues that inhibit the ultra-rapidly-activating delayed rectifier potassium current (IKur or IKsus), transient outward potassium (Ito), and acetylcholine-activated potassium current (IK.ACh).
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Page/Page column 11
(2008/12/08)
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- Sodium selenite-dimethylsulfoxide: a highly efficient reagent for dehydrogenation
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Sodium selenite in dimethylsulfoxide is a highly efficient reagent for dehydrogenation reactions and can be used under both thermal as well as microwave irradiation conditions. Using this reagent benzoins have been dehydrogenated to benzils, flavanones to flavones and 2'-hydroxy chalcones have been converted into flavones by cyclodehydrogenation.
- Lamba, Mandeep,Makrandi, Jagdish Kumar
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experimental part
p. 225 - 226
(2009/08/15)
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- Dimethylsulfoxide-iodine catalysed deprotection of 2′- allyloxychalcones: Synthesis of flavones
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A new one-pot method is described for the removal of O-allyl protecting groups under oxidative conditions at neutral pH. 2′-Allyloxychalcones undergo deprotection and subsequent oxidative cyclisation to give flavones. The general applicability of the reagent has been studied.
- Lokhande, Pradeep D.,Sakate, Sachin S.,Taksande, Kiran N.,Navghare, Beena
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p. 1573 - 1574
(2007/10/03)
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- An efficient conversion of 2'-hydroxychalcones into flavanones: Use of tetra-n-butylammonium iodide
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2'-Hydroxychalcones 1 possessing different substitution patterns in rings A and B, have been found to undergo efficient isomerization to the corresponding flavanones 2 when heated in ethanol with hydrochloric acid and tetra-n-butylammonium iodide.
- Dhawan, Deepika,Grover, S. K.
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- Oxidation of Flavanones using Thallium(III) Salts: A New Route for the Synthesis of Flavones and Isoflavones
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When treated with thallium(III) acetate in acetic acid or acetonitrile, flavanones undergo facile dehydrogenation to afford flavones whereas, upon treatment with thallium(III) toluene-p-sulfonate or thallium(III) nitrate in propionitrile or acetonitrile, respectively, they undergo oxidative 2,3-aryl migration to give isoflavones in high yield.
- Khanna, Mahavir S.,Singh, Om V.,Garg, Chandra P.,Kapoor, Ram P.
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p. 2565 - 2568
(2007/10/02)
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- Preparative and Regiochemical Aspects of the Palladium-Catalyzed Carbonylative Coupling of 2-Hydroxyaryl Iodides with Ethynylarenes
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The title reaction has been conveniently carried out in DMF at 60 deg C under 1 atm CO pressure using DBU as the base and Pd(OAc)2(DPPF)2 as the catalyst to afford generally mixtures of flavones 4 and aurones 5 in varying yields, depending on the substituents in the both reactants.Factors controlling the regioselectivity for 4 or 5 formation in this and in similar, previously reported, coupling procedures have been examined.
- Ciattini, Pier Giuseppe,Morera, Enrico,Ortar, Giorgio,Rossi, Sabina Strano
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p. 6449 - 6456
(2007/10/02)
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- Epoxidation of Flavones by Dimethyldioxirane
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The synthesis of epoxides 2 by epoxidation of flavones 1 with isolated dimethyldioxirane (as acetone solution) at subambient temperatures is reported.These labile epoxides were isolated and completely characterized by UV, IR, 1H and 13C NMR, MS, and C,H analyses.Warming to room temperature led to rearrangement to afford quantitatively the 3-hydroxyflavones 3b,h,i,n.Treatment of the epoxides 2b,f with methanol led to the 3-hydroxy-2-methoxyflavanones 4b,f, as a mixture of cis and trans isomers.
- Adam, Waldemar,Golsch, Dieter,Hadjiarapoglou, Lazaros
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p. 7292 - 7297
(2007/10/02)
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- Dehydrogenation of flavanones to flavones using thallium(III) acetate(TTA)
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A facile conversion of flavanones to flavones by dehydrogenation of the former using thallium(III) acetate is described.
- Singh, Om V.,Kapoor
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p. 1459 - 1462
(2007/10/02)
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- FLAVANOID PART 7 : A NOVEL PHOTOSYNTHESIS OF 3-α-HYDROXYBENZYLFLAVONES FROM 3-ARYLIDENEFLAVANONES
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E-3 Arylideneflavanones 4 on UV irradiation using quartzware undergo auto-oxidation to 3-aroylflavones 5.Photolysis using pyrex filter in the presence of iodoform furnishes 3-α-hydroxybenzylflavones indicating the intermediacy of the hydroperoxide 11 and form a new general method for the synthesis of these compounds not available by other routes.
- Dhande, V.P.,Thakwani (nee Joshi), Poonam,Marathe, K.G.
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p. 3015 - 3024
(2007/10/02)
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- Reaction of Hydroxylamine Hydrochloride with 2-Hydroxy-4'-methoxy-5-methyldibenzoylmethane and 4'-Methoxy-6-methylflavone
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2-Hydroxy-4'-methoxy-5-methyldibenzoylmethane (1) reacts with hydroxylamine hydrochloride in pyridine to give a mixture of 3-(2-hydroxy-5-methylphenyl)-5-(4-methoxyphenyl)isoxazole (2) and 3-(α-hydroxyamino-4-methoxystyryl)-5-methylbenzisoxazole (3).Simil
- Lohiya, S. B.,Ghiya, B. J.
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p. 873 - 876
(2007/10/02)
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- Oxidation of 2'Hydroxychalcones
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2'-Hydroxychalcones (1a-f) or the isomeric flavanones (IIa-f) on refluxing in DMSO for 30 min in the presence of catalytic amount of iodine afford the corresponding flavones (III) in high yields.This method is quicker and appears to be of general applicability.
- Doshi, A. G.,Soni, P. A.,Ghiya, B. J.
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- SYNTHESIS AND OXIDATION STUDIES OF SOME FLAVANONE N-SALICYLOYL HYDRAZONES WITH SELENIUM DIOXIDE
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Some newly synthesized flavanone hydrazones have been oxidized with selenium dioxide in dioxane + water system.The structures of the hydrazones and oxidation products have been established by microelemental analyses, m.m.p., co-TLC and spectral data.
- Shivhare, Abha,Kale, Arun V.,Berge, Diwakar, D.
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p. 107 - 110
(2007/10/02)
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- Reactions of 3-Bromoflavanones with Hydrazine Hydrate
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3-Bromoflavanones (I) react with hydrazine hydrate in ethanol to produce pyrazoles (V).The same reaction mixture after 48 hr at room temperature affords pyrazoles (V) and flavones (IV).In acetic acid medium, at room temperature, the reaction products are 3-bromoflavanone hydrazones (III) and flavone azines (II).However, when the reaction mixture is heated, only flavone azines (II) are formed.
- Reddy, N. J.,Sharma, T. C.
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p. 715 - 718
(2007/10/02)
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- Lead Tetraacetate Oxidation of 4-Oximinoflavans
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4-Oximinoflavans (I) give the corresponding flavanones (II), flavones (III), 3-acetoxyflavonols (IV) and 3-acetoxydihydroflavonols (V) on oxidation with lead tetraacetate in dry benzene.The yields of the major products, flavanones (II) range between 24 and 36percent.
- Kale, Arun V.,Berge, Diwakar D.
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p. 408 - 410
(2007/10/02)
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