- Palladium-catalyzed synthesis of flavones and chromones via carbonylative coupling of o-iodophenols with terminal acetylenes
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o-Iodophenols react with terminal acetylenes under carbon monoxide in the presence of palladium catalyst to give flavones or 2-substituted chromones.
- Kalinin,Shostakovsky,Ponomaryov
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- CF3SOCl-promoted intramolecular cyclization of β-diketones: An efficient synthesis of flavones
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An efficient intramolecular cyclization reaction of β-diketones containing a phenyl group with an ortho-hydroxyl substituent was achieved. Using CF3SOCl as an additive, the reaction took place under transition-metal-free and mild conditions. A series of flavones were synthesized in moderate to excellent yields.
- Sun, Dong-Wei,Zhou, Yong-Yan,Jiang, Min,Nian, Tang,Liu, Jin-Tao
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- Biocatalytic green alternative to existing hazardous reaction media: Synthesis of chalcone and flavone derivatives via the Claisen-Schmidt reaction at room temperature
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Owing to the increasing amount of waste materials around the globe, the conversion of waste or secondary by-products to value-added products for various applications has gained significant interest. Herein, two novel agro-food waste products, Musa sp. 'Malbhog' peel ash (MMPA) and Musa Champa Hort. ex Hook. F. peel ash (MCPA) are used as catalysts to promote an inexpensive, efficient and eco-friendly carbon-carbon bond forming crossed aldol reaction at room temperature in solvent free conditions. Furthermore, the resulting products were subjected to reactions with these promoters in an oxygen atmosphere and led to the formation of novel flavone derivatives. Moreover, the used catalysts were properly characterized using different sophisticated analytical techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), Brunauer-Emmett-Teller analysis (BET), Raman spectroscopy, scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS), transition electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) along with element detection using atomic absorption spectroscopy and ion chromatographic methods. These two approaches are metal free, as well as being devoid of any extra additives, co-catalysts, harsh conditions, the use of column chromatography for purification and result in a higher yield of the product within a short space of time. The catalytic abilities of the promoter were also examined to synthesize important bioactive molecules such as butein and apigenin at room temperature. With gram scale synthesis of the chalcone derivatives, the used catalysts (MMPA and MCPA) were further reused for five cycles and did not demonstrate any loss in catalytic activity.
- Tamuli, Kashyap J.,Sahoo, Ranjan K.,Bordoloi, Manobjyoti
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supporting information
p. 20956 - 20965
(2020/12/31)
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- Thermally regulated molybdate-based ionic liquids toward molecular oxygen activation for one-pot oxidative cascade catalysis
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One-pot oxidative cascade catalysis plays a central role in the synthesis of key pharmaceutical and industrial molecules. Although ionic liquids are one of the most promising solvents and reaction media, the breakthrough of their catalysis in aerobic oxidation is very challenging due to the difficulty in the direct activation of molecular oxygen. Herein, a family of novel thermally regulated molybdate-based ionic liquids (Mo-ILs) has been designed and developed for the first time toward molecular oxygen activation for highly efficient tandem oxidative catalysis. Three diverse one-pot oxidative cascade processes for the syntheses of various flavones, imines, and benzyl benzoates were achieved with good to excellent yields using the Mo-IL [Bmim]2[MoO4] as a catalyst under air conditions. The results of spectroscopic investigations and quantum-chemical calculations further demonstrated that a thermally regulated proton migration between the cation [Bmim] and anion [MoO4] was the key to forming N-heterocyclic carbene and thereby to effortlessly promoting the generation of O2- active species from molecular oxygen, which results in excellent catalytic performance in these three aerobic tandem oxidations. Our work extends the application area of ILs as the sole catalyst to one-pot aerobic oxidative cascade catalysis, which could have pronounced implications in future work.
- Song, Zhibin,Huang, Wei,Zhou, Yan,Tian, Zi-Qi,Li, Zhang-Min,Tao, Duan-Jian
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p. 103 - 109
(2020/01/21)
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- An efficient TBHP/TBAI-mediated protocol for the synthesis of 4H-chromen-4-ones from chroman-4-ones via oxidative C–C bond formation
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Abstract: A transition metal-free and efficient TBHP/TBAI-mediated protocol has been developed for the synthesis of 4H-chromen-4-ones from chroman-4-ones via oxidative C–C bond formation. It proceeds in the presence of a catalytic amount of tetrabutylammonium iodide and oxidant tert-butyl hydroperoxide (TBHP, 5–6 M in decane) to afford the corresponding products in good to excellent yields. Furthermore, it has been observed that an increase in the concentration of TBHP to 30 mol % drastically increases the yield of 4H-chromen-4-ones, any further increase will lead to a decrease in percent yield. The mechanism of this reaction involves the generation of tertiary butoxide radical initially which by oxidative single-electron transformation is converted to iodochroman-4-one. Later the hydrogen iodide is removed from iodochroman-4-one to give the desired product, i.e. 4H-chromen-4-ones. Moreover, this is a rare example of the n-Bu4NI/TBHP-mediated C–C bond through dehydrogenative reaction. Graphic abstract: [Figure not available: see fulltext.]
- Agisho, Habtamu Abebe,Hairat, Suboot,Zaki, Mehvash
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p. 599 - 603
(2020/05/04)
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- Rhodium(III)-catalyzed one-pot synthesis of flavonoids from salicylaldehydes and sulfoxonium ylides
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Rh(III)-catalyzed C–H activation of salicylaldehyde followed by an insertion reaction with sulfoxonium ylides and cyclization is applied to the synthesis of flavonoids. This one-pot strategy exhibits good functional group tolerance and gives flavones in moderate-to-good yields.
- Cheng, Kang,Chen, Jinkang,Jin, Licheng,Zhou, Jian,Jiang, Xinpeng,Yu, Chuanming
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p. 392 - 398
(2019/09/03)
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- An efficient tandem synthesis of chromones from: O -bromoaryl ynones and benzaldehyde oxime
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An effective transition-metal-free strategy was developed for the preparation of chromones from o-bromoaryl ynones and benzaldehyde oxime through sequential C-O bond formation. This cyclization reaction could well tolerate a wide range of functional groups, and the corresponding chromones were given in moderate to excellent yields. Mechanistically, benzaldehyde oxime as a hydroxide source and 1,3-diketone derivatives as reaction intermediates were involved in this transformation.
- Zhang, Jing-Wen,Yang, Wan-Wan,Chen, Lu-Lu,Chen, Pei,Wang, Yan-Bo,Chen, Dan-Yun
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p. 7461 - 7467
(2019/08/20)
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- Single Step Synthetic Method for Homoisoflavonoids and Flavones
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The present invention relates to a one-pot synthesis method of homoisoflavonoid derivatives and flavone derivatives. By conducting a reaction of salicylicaldehyde and arylalkynoic acid in the presence of a ruthenium catalyst and a base, homoisoflavonoids and flavones can be selectively obtained through a single step (one-pot). Therefore, a synthesis method of the present invention is a simple/disposable selective metal catalyst synthesis method, which can be used to manufacture a plurality of bioactive materials.COPYRIGHT KIPO 2019
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Paragraph 0071; 0354-0358; 0360; 0362-0365; 0377-0380
(2019/09/12)
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- Rh(III)-Catalyzed Aldehydic C?H Functionalization Reaction between Salicylaldehydes and Sulfoxonium Ylides
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A novel aldehydic C?H functionalization reaction between salicylaldehydes and sulfoxonium ylides has been developed under rhodium(III) catalysis, affording coupling products in moderate to good yields. A plausible mechanism involving aldehydic C(sp2)?H activation by rhodium(III) and rhodium(III) catalyzed carbene insertion is also proposed. It was also found that the aldehydic C?H functionalization followed by dehydrative cyclization was able to produce flavonoids in one-pot. (Figure presented.).
- Xu, Guo-Dong,Huang, Kenneth L.,Huang, Zhi-Zhen
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supporting information
p. 3318 - 3323
(2019/06/25)
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- Rational design for multicolor flavone-based fluorophores with aggregation-induced emission enhancement characteristics and applications in mitochondria-imaging
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Fluorophores with aggregation-induced emission enhancement (AIEE) properties have attracted more attention in recent years. In order to realise more valuable applications, the different kinds of AIEE molecules are in serious need of further development. Therefore, a novel flavone-based AIEE system derived from restriction of intramolecular rotation (RIR) was designed and synthesized in this work. The results revealed that six of the compounds showed typical AIEE characteristics, with fluorescence emissions from purple, blue, cyan to green, tunable by changing substituent groups. This flavone-based AIEE system has never been reported before. The AIEE characteristics were investigated by optical spectroscopy, fluorescence photographs, scanning electron microscopy (SEM), fluorescence quantum yields (φF) and fluorescence lifetime in the CH3OH/H2O mixed solution. Moreover, benefiting from the simple structures and small molecular weight, they could permeate cells faster than current high-molecular-weight AIEE molecules. Furthermore, to examine possible biomedical applications, fluorescence imaging in living A549 lung cells and cell viabilities were examined, and the results displayed that these fluorophores showed good cellular uptake and low cytotoxicity within the experimental concentration range. In addition, these AIEE compounds possessed excellent specificity for mitochondrial targeting and mitochondrial morphological change tracking, besides, they displayed superior photostability, which indicated they are potential candidates for mitochondrial imaging.
- Liu, Liyan,Lei, Yaohui,Zhang, Jianhui,Li, Na,Zhang, Fan,Wang, Huaqiao,He, Feng
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- 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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- One Pot Synthesis of γ-Benzopyranones via Iron-Catalyzed Aerobic Oxidation and Subsequent 4-Dimethylaminopyridine Catalyzed 6-endo Cyclization
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One-pot synthesis of γ-benzopyranones was realized in decent yields and excellent regioselectivities via iron-catalyzed aerobic oxidation and 4-dimethylaminopyridine-catalyzed cyclization of related propargylic alcohols. Derivatizations to aromatic substituted γ-benzopyranones and synthesis of naturally occurring 3′,4′-dimethoxyflavone have also been realized. (Figure presented.).
- Zhai, Di,Chen, Lingzhu,Jia, Minqiang,Ma, Shengming
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supporting information
p. 153 - 160
(2017/11/23)
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- A transition-metal-free fast track to flavones and 3-arylcoumarins
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A highly regioselective and transition-metal free one-pot arylation of chromenones with arylboronic acids has been achieved employing K2S2O8. The procedure consists of a sequence of some reactions including an arylation/decarboxylation cascade and proceeds well in aqueous media to afford biologically interesting flavones and 3-arylcoumarins. This method exhibited excellent selectivity and functional group tolerance under mild conditions. The reaction also showed perfect efficacy for the preparation of styryl coumarins.
- Golshani, Mostafa,Khoobi, Mehdi,Jalalimanesh, Nafiseh,Jafarpour, Farnaz,Ariafard, Alireza
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supporting information
p. 10676 - 10679
(2017/10/06)
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- Ruthenium-Catalyzed C-H Activation of Salicylaldehyde and Decarboxylative Coupling of Alkynoic Acids for the Selective Synthesis of Homoisoflavonoids and Flavones
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Homoisoflavonoids were formed in DMSO exclusively, and flavones were formed in t-AmOH when salicylaldehyde and alkynoic acids reacted with [Ru(p-cymene)Cl2]2 and CsOAc. They were formed through C-H activation of salicylaldehyde and decarboxylative coupling of alkynoic acid. This reaction system showed good yields, broad substrate scope, and good functional group tolerance. It was found that chalcone was an intermediate in the formation of both homoisoflavonoid and flavone.
- Raja, Gabriel Charles Edwin,Ryu, Ji Yeon,Lee, Junseong,Lee, Sunwoo
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supporting information
p. 6606 - 6609
(2017/12/26)
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- Rapid synthesis of flavone-based monoamine oxidase (MAO) inhibitors targeting two active sites using click chemistry
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A new library of flavone derivatives targeting two active sites of monoamine oxidases (“aromatic cage” and substrate cavity) were designed and synthesized using click chemistry (CuAAC reaction) between 6-N3-2-phenyl chromones (Az1–Az2) and a series of alkynes (k1–k20). Their inhibitory activities against MAO isoforms (MAO-A and MAO-B) are evaluated. Compounds with fluorine, amide bonds, or amino bonds have shown better inhibition. The most potent flavone MAO inhibitor studied is Az2k19 (1.6?μm for MAO-A, 2.1?μm for MAO-B), while Az1k15 and Az2k15 displayed better selectivity toward MAO-B (SI?>?10). Docking studies are in accordance with our hypothesis that these inhibitors are most likely located at both the substrate cavity and the “aromatic cage”. Our results show that it is considerable to develop new MAO inhibitors from C6 substitution of flavone derivatives and that these compounds are also potential for the treatment of diseases associated with MAOs.
- Jia, Wei Zhen,Cheng, Feng,Zhang, Yin Jun,Ge, Jin Yan,Yao, Shao Q.,Zhu, Qing
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p. 141 - 151
(2016/12/16)
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- Synthesis of 4H-Chromen-4-one Derivatives by Intramolecular Palladium-Catalyzed Acylation of Alkenyl Bromides with Aldehydes
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The palladium-catalyzed intramolecular acylation of alkenyl bromides and aldehydes was developed for an efficient synthesis of 4H-chromen-4-ones. With Pd(PPh3)4/Xphos as the catalyst and K2CO3 as the base, this protocol was applied to synthesize a small library of diversely functionalized flavonoids in moderate to good yields in 1,4-dioxane.
- Yue, Yixia,Peng, Jinsong,Wang, Deqiang,Bian, Yunyun,Sun, Peng,Chen, Chunxia
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p. 5481 - 5486
(2017/05/24)
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- Identification and structure activity relationship of novel flavone derivatives that inhibit the production of nitric oxide and PGE2 in LPS-induced RAW 264.7 cells
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In an effort to identify novel anti-inflammatory compounds, a series of flavone derivatives were synthesized and biologically evaluated for their inhibitory effects on the production of nitric oxide (NO) and prostaglandin E2 (PGE2), representative pro-inflammatory mediators, in LPS-induced RAW 264.7 cells. Their structure-activity relationship was also investigated. In particular, we found that compound 3g displayed more potent inhibitory activities on PGE2 production, similar inhibitory activities on NO production and less weak cytotoxicity than luteolin, a natural flavone known as a potent anti-inflammatory agent.
- An, Ji-Young,Lee, Hwi-Ho,Shin, Ji-Sun,Yoo, Hyung-Seok,Park, Jong Seon,Son, Seung Hwan,Kim, Sang Won,Yu, Jihyun,Lee, Jun,Lee, Kyung-Tae,Kim, Nam-Jung
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p. 2613 - 2616
(2017/05/10)
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- Method for synthesizing flavonoids compound in one step by virtue of catalysis of 1,3-dialkylimidazolium oxometallate
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The invention discloses a method for synthesizing a flavonoids compound in one step by virtue of catalysis of 1,3-dialkylimidazolium oxometallate. The method is characterized by comprising the following steps: sequentially adding raw material benzaldehyde or benzaldehyde derivatives, raw material 2-hydroxyacetophenone or 2-hydroxyacetophenone derivatives, an ion liquid catalyst and an organic solvent into a reactor, stirring, heating to 50 to 90 DEG C, reacting for 2 to 7 hours at a constant temperature by taking oxygen or air as an oxidant, cooling, distilling under reduced pressure, carrying out the column chromatography, and re-crystallizing and separating to obtain the target product flavonoids compound. The method has the characteristics that the ion liquid is used as the catalyst, the yield of the flavonoids compound synthesized in one step reaches 85 percent or more, therefore, compared with the traditional synthetic method, the reaction flow is shortened, and the synthetic efficiency of the flavonoids compound is remarkably improved. The method has advantages of high product yield, low production cost, simple operation procedures, moderate reaction conditions and the like and is proved to be a novel method for high-efficiently synthesizing the flavonoids compound.
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Paragraph 0103; 0104; 0105; 0106; 0107
(2016/10/08)
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- Mild and efficient organocatalytic method for the synthesis of flavones
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A convenient and efficient organocatalytic procedure for the selective cyclization of 1,3-diketones to give aromatic substituted 4H-chromen-4-ones under mild reaction conditions using N-triflyl phosphoramide is described. Application of the described conditions is presented in a formal synthesis of (S)-flavanone.
- Stanek, Filip,Stodulski, Maciej
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p. 3841 - 3843
(2016/08/02)
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- A very simple solvent-free method for the synthesis of 2-arylchromones using KHSO4 as a recyclable catalyst
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An efficient and solvent-free procedure for the synthesis of flavones using KHSO4 as a recyclable catalyst is described. The methodology represents an environmentally friendly process in comprehensive consideration compared with other catalytic systems listed in publications. This method provides a clean, simple, solvent-free reaction and useful alternatives to prepare flavones and chromones. The use of KHSO4 catalyst provides excellent yields, also leading to an easy separation and recovery of the catalysts, which allows both low environmental impact and low cost. Other green advantages of the method are the low formation of wastes and the replacement of corrosive, soluble mineral acids.
- Pérez, María,Ruiz, Diego,Autino, Juan,Sathicq, Angel,Romanelli, Gustavo
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p. 551 - 555
(2016/06/01)
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- Pd(OAc)2/S=PPh3 accelerated activation of gem-dichloroalkenes for the construction of 3-arylchromones
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The Pd-catalyzed regioselective intramolecular nucleophilic substitution of gem-dichloroalkene derivatives with salicylaldehydes leading to the synthesis of 3-arylchromones has been developed. Pd(OAc)2/S=PPh3 could activate gem-dichloroalkenes and undergo nucleophilic substitution by salicylaldehydes with the aid of a base.
- Liu, Jianming,Song, Weiwei,Yue, Yuanyuan,Liu, Ren,Yi, Hong,Zhuo, Kelei,Lei, Aiwen
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supporting information
p. 17576 - 17579
(2015/12/08)
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- A versatile approach to flavones via a one-pot Pd(II)-catalyzed dehydrogenation/oxidative boron-Heck coupling sequence of chromanones
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A variety of flavones were expediently synthesized from readily accessible chromanones via a one-pot sequence involving Pd(ii)-catalyzed dehydrogenation and oxidative boron-Heck coupling with arylboronic acid pinacol esters. In particular, the use of arylboronic acid pinacol esters was found to significantly improve the yield of the reaction.
- Lee, Jun,Yu, Jihyun,Son, Seung Hwan,Heo, Jinyuk,Kim, Taelim,An, Ji-Young,Inn, Kyung-Soo,Kim, Nam-Jung
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p. 777 - 784
(2016/01/12)
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- Intervention in cyclophosphamide induced oxidative stress and DNA damage by a flavonyl-thiazolidinedione based organoselenocyanate and evaluation of its efficacy during adjuvant therapy in tumor bearing mice
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A novel flavonyl-thiazolidinedione based organoselenocyanate compound was synthesized and established as nontoxic at the doses of 2.5 and 5 mg/kg b.w. in mice. Oral administration of the compound in combination with cyclophosphamide (CP) resulted in an im
- Roy, Somnath Singha,Chakraborty, Pramita,Bhattacharya, Sudin
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p. 195 - 209
(2014/01/23)
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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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- Construction of the flavones and aurones through regioselective carbonylative annulation of 2-bromophenols and terminal alkynes
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The easily available and efficient catalyst containing a benzimidazolium ligand and PdCl2(PPh3)2 demonstrated excellent catalytic activity to construct the flavones and aurones, respectively. This reaction can be operated under mild conditions, affording the desired products in moderate to good yields. This protocol was used to prepare the flavones and aurones by a slight modification of amines.
- Liu, Jianming,Liu, Muwen,Yue, Yuanyuan,Zhang, Ningfei,Zhang, Yuanli,Zhuo, Kelei
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supporting information
p. 1802 - 1807
(2013/04/24)
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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 of chromones through LiOtBu/air-mediated oxidation and regioselective cyclization of o-hydroxyphenyl propargyl carbinols
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A cascade oxidative cyclization reaction for the synthesis of chromone derivatives was developed by using LiOtBu as a mediator and air as an oxidant. The reaction was carried out without the assistance of a transition metal under mild conditions to afford the chromones in good yields with high regioselectivities. A tandem reaction for the synthesis of various chromones was developed. LiOtBu was used as a mediator and air was used as a clean oxidant. The reaction generally showed high regioselectivity under mild conditions. Extensive research showed that dehydrogenative oxidation of the alcohols under strongly basic conditions was the crucial step, and Li+ was also found to play an important role in this process. Copyright
- Zhang, Shuai,Wan, Changfeng,Wang, Qiang,Zhang, Baiqun,Gao, Lingfeng,Zha, Zhenggen,Wang, Zhiyong
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supporting information
p. 2080 - 2083
(2013/05/09)
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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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p. 770 - 773
(2012/06/30)
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- Palladium-catalyzed dehydrogenation/oxidative cross-coupling sequence of β-heteroatom-substituted ketones
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Concise and selective: The title one-pot sequence allows formation of the enone functionality and subsequent cross-coupling. The process provides access to highly functionalized cyclic enolones and enaminones from readily accessible β-heteroatom-substitut
- Moon, Youngtaek,Kwon, Daeil,Hong, Sungwoo
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supporting information
p. 11333 - 11336,4
(2012/12/12)
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- Investigation on the substitution effects of the flavonoids as potent anticancer agents: A structure-activity relationships study
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Three series of flavonoid analogues substituted with different aminomethyl substitutions at C-6, C-7, and C-8 were designed and synthesized for the structure-activity relationship studies as potent anticancer agents. The prepared analogues were evaluated for their in vitro inhibitory activity against the growth of the hepatic cancer cell lines HepG2 and SMMC-7721. Structure-activity relationships indicated that not only the compounds with amino methyl groups were more active than those without the groups in the same series but also the compounds substituted by aminomethyl groups at position C-8 were more active than those at positions C-6 and C-7.
- Wang, Xiao-Bing,Yang, Lei,Kong, Ling-Yi,Liu, Wei,Guo, Qing-Long
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p. 1833 - 1849,17
(2020/07/30)
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- Palladium-catalyzed carbonylation reaction of aryl bromides with 2-hydroxyacetophenones to form flavones
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Flavone of the month: A general and efficient method for the palladium-catalyzed carbonylative synthesis of flavones has been developed (see scheme). Starting from aryl bromides and 2-hydroxyacetophenones, the corresponding flavones have been isolated in good yields. Copyright
- Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
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supporting information
p. 12595 - 12598
(2012/11/07)
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- Synthetic approach to flavanones and flavones via ligand-free palladium(ii)-catalyzed conjugate addition of arylboronic acids to chromones
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The remarkable catalytic effects of Fe(OTf)3 in the context of the Pd(ii)-catalyzed conjugate addition of arylboronic acids to chromones were observed to yield a variety of flavanones under mild conditions. The addition of catalytic amounts of DDQ and KNO2 to the reactions exclusively yielded flavone analogs. The reaction scope for the transformation was fairly broad, affording good yields of a wide range of flavanones and flavones, which are privileged structures in many biologically active compounds.
- Kim, Donghee,Ham, Kyungrok,Hong, Sungwoo
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experimental part
p. 7305 - 7312
(2012/09/22)
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- A new synthesis of flavones and pyranoflavone by intramolecular photochemical Wittig reaction in water
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A new synthetic approach toward the synthesis of flavones and pyranoflavone has been developed by light induced intramolecular photochemical Wittig reaction in water onto aryloxycarbonyl groups and suitably substituted phosphonium bromides sans any phase transfer catalyst or promoter.
- Das, Jhantu,Ghosh, Somnath
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p. 7189 - 7194
(2012/01/05)
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- Ionic liquid mediated Cu-catalyzed cascade oxa-Michael-oxidation: Efficient synthesis of flavones under mild reaction conditions
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Flavonoids are a class of natural products, found in a wide range of vascular plants and dietary components. Their low toxicity and extensive biological activities, including anti-cancer and anti-bacterial, have made them attractive candidates to serve as therapeutic agents for many diseases. Herein, we disclose a highly efficient synthetic method of CuI-catalyzed cascade oxa-Michael-oxidation, using chalcones as substrates, mediated by the ionic liquid [bmim][NTf2] at a low temperature. This efficient synthetic method has demonstrated high synthetic utility and can afford flavones in good to high yields (up to 98%).
- Du, Zhiyun,Ng, Huifen,Zhang, Kun,Zeng, Huaqiang,Wang, Jian
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scheme or table
p. 6930 - 6933
(2011/11/04)
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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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- A novel one pot route to flavones under dual catalysis, an organo- and a Lewis acid catalyst
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Substituted phenylacetylenes react with various o-hydroxy aromatic aldehydes under dual catalysis of piperidine and FeCl3 in refluxing toluene to yield flavones in good to excellent yield. Atmospheric oxygen acts as stoichiometric oxidant in the process. Some of these compounds had been recently reported to show fair insecticidal activity against Spodoptera frugiperda.
- Maiti, Gourhari,Karmakar, Rajiv,Bhattacharya, Rudraksha N.,Kayal, Utpal
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supporting information; experimental part
p. 5610 - 5612
(2011/11/12)
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- Transition-metal-free intramolecular Ullmann-type O-arylation: Synthesis of chromone derivatives
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(Chemical Equation Presented) Expect the upexpected: A transition-metal- free approach to access chromone derivatives has been developed. The intramolecular O-arylation of substituted 1-(2-haloaryl)-propane-1,3-diones in DMF in the presence of K2CO3 gave the corresponding target products in good to excellent yields (see scheme; DMF = N,N′- dimethylformamide).
- Zhao, Jie,Zhao, Yufen,Fu, Hua
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p. 3769 - 3773
(2011/05/15)
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- Wells-Dawson heteropolyacid as reusable catalyst for sustainable synthesis of flavones
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The behavior of Wells-Dawson (H6P2W 18O62·24H2O, WD) acid, both bulk and supported on silica, for the cyclodehydration reaction of 1-(2-hydroxyphenyl)-3- phenyl-1,3-propanedione to obtain flavone was studied in heterogeneous conditions, using toluene as solvent. Catalytic experiences with bulk and supported catalysts with different WD acid loadings and reuse of the catalysts were done. The catalytic activity of supported catalysts was higher than that of the bulk catalyst, and their activity was almost constant after three reaction cycles. The following reaction conditions: reflux toluene and 1% mmol of WD supported on silica (0.4 g WD acid by gram of silica) were used for the preparation of five flavones. Yields above 85% were obtained in 4-5 h.
- Bennardi, Daniel O.,Romanelli, Gustavo P.,Sathicq, ángel G.,Autino, Juan C.,Baronetti, Graciela T.,Thomas, Horacio J.
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experimental part
p. 68 - 73
(2012/02/05)
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- A facile synthesis of flavones catalysed by gallium(III) triflate
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Ga(OTf)3 was explored as a novel catalyst for the cyclisation of 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones in nitromethane to flavones with excellent yields.
- Jin, Can,He, Fei,Wu, Huayue,Chen, Jiuxi,Su, Weike
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experimental part
p. 27 - 29
(2009/09/25)
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- Mechanically activated solid-state synthesis of flavones by high-speed ball milling
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An efficient, mechanically activated solid-state synthesis of flavones from 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones using high-speed ball milling is described. This method has notable advantages in terms of good yield, short reaction time, and neat conditions.
- Zhu, Xingyi,Li, Zhenhua,Shu, Qiangfeng,Zhou, Chenfeng,Su, Weike
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experimental part
p. 4199 - 4211
(2010/01/16)
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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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- Fast synthesis of some flavones under microwave irradiation
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Reactions under microwave irradiation occur under solvent free conditions. Such reactions occur in much shorter time than the usual ones. Fast synthesis of flavone from o-hydroxyacetophenone has been achieved in three steps under microwave irradiation.
- Mumtazuddin
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p. 835 - 837
(2007/10/03)
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- A selective transformation of flavanones to 3-bromoflavones and flavones under microwave irradiation
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This paper presents the first report of a highly selective transformation of flavanones to 3-bromoflavones or flavones by microwave irradiation of the corresponding flavanone reactants and N-bromosuccinimide (NBS) in the presence of a catalytic amount of 2,2′-azobis(isobutyronitrile) (AIBN). The combination of good to excellent yields, shorter reaction time (10 min), and high levels of functional group compatibility make this an attractive synthetic approach to 3-bromoflavones and flavones.
- Zhou, Zhongzhen,Zhao, Peiliang,Huang, Wei,Yang, Guangfu
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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 environmentally benign synthesis of flavones from 1,3-diketones using silica gel supported NaHSO4 catalyst
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A simple and enviromentaly benign method for synthesis of flavones is described via dehydrative cyclisation of o-hydroxydibenzoylmethane using silica gel supported NaHSO4 catalyst.
- Kucukislamoglu, Mustafa,Nebioglu, Mehmet,Zengin, Mustafa,Arslan, Mustafa,Yayli, Nurettin
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p. 556 - 557
(2007/10/03)
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- Manganese(III) acetate mediated oxidation of flavanones: A facile synthesis of flavones
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Oxidation of flavanones (1a-o) with manganese(III) acetate by heating in acetic acid in presence of perchloric acid afforded exclusively flavones (2a-o) by dehydrogenation in almost quantitative yields. Copyright Taylor & Francis, Inc.
- Singh, Om V.,Muthukrishnan,Raj, Gopan
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p. 2723 - 2728
(2007/10/03)
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- Refinement and evaluation of a pharmacophore model for flavone derivatives binding to the benzodiazepine site of the GABAA receptor
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To further develop and evaluate a pharmacophore model previously proposed by Cook and co-workers (Drug Des. Discovery 1995, 12, 193-248) for ligands binding to the benzodiazepine site of the GABAA receptor, 40 new flavone derivatives have been synthesized and their affinities for the benzodiazepine site have been determined. Two new regions of steric repulsive interactions between ligand and receptor have been characterized, and the receptor region in the vicinity of 6- and 3′-substituents has been mapped out. 2′-Hydroxy substitution is shown to give a significant increase in affinity, which is interpreted in terms of a novel hydrogen bond interaction with the previously proposed hydrogen bond-accepting site A2. On the basis of the results of these studies and the refined pharmacophore model, 5′-bromo-2′-hydroxy-6-methylflavone, the highest affinity flavone derivative reported so far (Ki = 0.9 nM), was successfully designed. A comparison of the pharmacophore model with a recently proposed alternative model (Marder; et al. Bioorg. Med. Chem., 2001, 9, 323-335) has been made.
- Kahnberg, Pia,Lager, Erik,Rosenberg, Celia,Schougaard, Jette,Camet, Linda,Sterner, Olov,Nielsen, Elsebet ?stergaard,Nielsen, Mogens,Liljefors, Tommy
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p. 4188 - 4201
(2007/10/03)
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- Antimicrobial effects of novel siderophores linked to β-lactam antibiotics
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As a strategy to increase the penetration of antibiotic drugs through the outer membrane of Gram-negative pathogens, facilitated transport through siderophore receptors has been frequently exploited. Hydroxamic acids, catechols, or very close isosteres of catechols, which are mimics of naturally occurring siderophores, have been used successfully as covalently linked escorting moieties, but a much wider diversity of iron binding motifs exists. This observation, coupled to the relative lack of specificity of siderophore receptors, prompted us to initiate a program to identify novel, noncatechol siderophoric structures. We screened over 300 compounds for their ability to (1) support growth in low iron medium of a Pseudomonas aeruginosa siderophore biosynthesis deletion mutant, or (2) compete with a bactericidal siderophore-antibiotic conjugate for siderophore receptor access. From these assays we identified a set of small molecules that fulfilled one or both of these criteria. We then synthesized these compounds with functional groups suitable for attachment to both monobactam and cephalosporin core structures. Siderophore-β-lactam conjugates then were tested against a panel of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus strains. Although several of the resultant chimeric compounds had antimicrobial activity approaching that of ceftazidime, and most compounds demonstrated very potent activity against their cellular targets, only a single compound was obtained that had enhanced, siderophore-mediated antibacterial activity. Results with tonB mutants frequently showed increased rather than decreased susceptibilities, suggesting that multiple factors influenced the intracellular concentration of the drugs. (C) 2000 Elsevier Science Ltd.
- Kline,Fromhold,McKennon,Cai,Treiberg,Ihle,Sherman,Schwan,Hickey,Warrener,Witte,Brody,Goltry,Barker,Anderson,Tanaka,Shawar,Nguyen,Langhorne,Bigelow,Embuscado,Naeemi
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- Hypervalent iodine oxidation of flavanones: A new synthesis of methyl 2-aryl-2,3-dihydrobenzofuran-3-carboxylates by 1,2-aryl shift
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Flavanones (1), on oxidation with (diacetoxyiodo)benzene-sulfuric acid (DIB-H2SO4) or (hydroxy(tosyloxy)iodo)benzene (HTIB) in trimethyl orthoformate, undergo facile ring contraction by 1,2-aryl shift, thereby yielding methyl 2-aryl-2,3-dihydrobenzofuran-3-carboxylates (4) as major products (40-80%). cis-3-Methoxyflavanones (5) and flavones (3) are the minor products formed in variable ratios.
- Prakash,Tanwar
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p. 1168 - 1171
(2007/10/02)
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