- Lewis Acid-catalysed Facile Elimination of the Diazo Group in 3-Diazochromanones. Novel Conversion of Chromanones into Chromones
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3-Diazochromanones undergo rapid elimination of the diazo group in presence of BF3- Et2O to furnish chromones.
- Mandal, Pranab,Venkateswaran, Ramanathapuram V.
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- Oxidation of chromanones and 2-spirochromanones with [hydroxy(tosyloxy)iodo]benzene in acetonitrile under reflux as well as ultrasound: A convenient route for the synthesis of chromones, tetrahydroxanthones and their higher homologues
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Oxidation of chromanones (1a-i) and 2-spiro-chromanones (1j-m) using [hydroxy(tosyloxy)iodo]benzene in refluxing acetonitrile as well as using ultrasound via dehydrogenation and 2,3-alkyl migration provides a convenient route for the synthesis of chromones (2a-i), tetrahydroxanthones (2j, k) and their higher homologues (2l, m). The ultrasound also enhances substantially the rate of above transformations.
- Kumar,Singh,Prakash,Singh
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- Gold(I)-Catalyzed Hydroxy Group Assisted C(sp2)-H Alkylation of Enaminones with Diazo Compounds to Access 3-Alkyl Chromones
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A strategy for expedient synthesis of 3-substituted chromones from easily available o-hydroxyarylenaminones and diazo compounds has been developed. Carefully conducted experimental and computational studies led us to propose an uncommon mechanistic pathway involving the hydroxyl group assisted alkylation of enaminones with in situ generated gold carbenes.
- Bagle, Pradip N.,Mane, Manoj V.,Sancheti, Shashank P.,Gade, Amol B.,Shaikh, Samir R.,Baik, Mu-Hyun,Patil, Nitin T.
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- Exploiting a silver-bismuth hybrid material as heterogeneous noble metal catalyst for decarboxylations and decarboxylative deuterations of carboxylic acids under batch and continuous flow conditions
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Herein, we report novel catalytic methodologies for protodecarboxylations and decarboxylative deuterations of carboxylic acids utilizing a silver-containing hybrid material as a heterogeneous noble metal catalyst. After an initial batch method development, a chemically intensified continuous flow process was established in a simple packed-bed system which enabled gram-scale protodecarboxlyations without detectable structural degradation of the catalyst. The scope and applicability of the batch and flow processes were demonstrated through decarboxylations of a diverse set of aromatic carboxylic acids. Catalytic decarboxylative deuterations were achieved on the basis of the reaction conditions developed for the protodecarboxylations using D2O as a readily available deuterium source.
- ?tv?s, Sándor B.,Fül?p, Ferenc,Kónya, Zoltán,Kukovecz, ákos,Márton, András,Mészáros, Rebeka,Pálinkó, István,Szabados, Márton,Varga, Gábor
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p. 4685 - 4696
(2021/07/12)
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- Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
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The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
- Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
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supporting information
p. 16470 - 16485
(2021/10/20)
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- Iron-Catalyzed ?±,?-Dehydrogenation of Carbonyl Compounds
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An iron-catalyzed α,β-dehydrogenation of carbonyl compounds was developed. A broad spectrum of carbonyls or analogues, such as aldehyde, ketone, lactone, lactam, amine, and alcohol, could be converted to their α,β-unsaturated counterparts in a simple one-step reaction with high yields.
- Zhang, Xiao-Wei,Jiang, Guo-Qing,Lei, Shu-Hui,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
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supporting information
p. 1611 - 1615
(2021/03/03)
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- Iodine-Mediated Synthesis of 2-(Methylthio)-4 H-chromen-4-ones and Study of Their Halogenation Reactions
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An efficient iodine-mediated method is developed for the synthesis of functionalized 2-(methylthio)-4H-chromen-4-ones by intramolecular cyclization of easily accessible 1-(2-benzyloxy-aryl)-3,3-bis-methylsulfanyl-propenones. The synthesized chromen-4-ones turn out to be a key precursor for various kinds of chemical reactions. Mechanistically, we observed that iodine-mediated intramolecular cyclization of ketene dithioacetal proceeded through a radical pathway. 3-Halo-2-(methylthio)-4H-chromen-4-ones were achieved via various two- or one-pot halogenation approaches.
- Elagamy, Amr,Pratap, Ramendra,Shah, Chandan,Shaw, Ranjay
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p. 9478 - 9489
(2021/07/28)
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- Visible Light-Promoted Selenylation/Cyclization of Enaminones toward the Formation of 3-Selanyl-4H-Chromen-4-Ones
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A simple and efficient visible-light-promoted selenylation/cyclization of enaminones have been realized for the practical synthesis of 3-selanyl-4H-chromen-4-ones. This reaction is performed in the mild conditions, no transition metal catalyst or photocatalysts and no additional oxidants are required. In addition, the 3-selanyl-4H-chromen-4-ones could be easily converted to selanyl-functionalized pyrimidines by reacting with benzamidine substrates. (Figure presented.).
- Liu, Hao-Yang,Zhang, Jia-Rong,Huang, Guo-Bao,Zhou, Yi-Huan,Chen, Yan-Yan,Xu, Yan-Li
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supporting information
p. 1656 - 1661
(2021/02/12)
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- Heterogeneously Catalyzed Selective Decarbonylation of Aldehydes by CeO2-Supported Highly Dispersed Non-Electron-Rich Ni(0) Nanospecies
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Aldehyde decarbonylation has been extensively investigated, primarily using noble-metal catalysts; however, nonprecious-base-metal-catalyzed aldehyde decarbonylation has been hardly reported. We have established an efficient selective aldehyde decarbonylation reaction with a broad substrate scope and functional group tolerance utilizing a heterogeneous Ni(0) nanospecies catalyst supported on CeO2. The high catalytic performance is attributable to the highly dispersed and non-electron-rich Ni(0) nanospecies, which possibly suppress a side reaction producing esters and adsorbed CO-derived inhibition of the catalytic turnover, according to detailed catalyst characterization and kinetic evaluation.
- Matsuyama, Takehiro,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
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p. 13745 - 13751
(2021/11/17)
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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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- Iodine-catalyzed α,β-dehydrogenation of ketones and aldehydes generating conjugated enones and enals
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A transition metal-free α,β-dehydrogenation of ketones and aldehydes was developed. This reaction was conducted in a facile I2/KI/DMSO system to produce the corresponding unsaturated compounds in good to high yields. The gram-scale experiment also indicated the potential synthetic value of this new reaction in organic synthesis. In the reaction, DMSO acted as both solvent and mild oxidant.
- Cao, Yuanjie,Chen, Tieqiao,Huang, Tianzeng,Liu, Long
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supporting information
p. 8697 - 8701
(2020/06/08)
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- CeO2-Supported Pd(II)-on-Au Nanoparticle Catalyst for Aerobic Selective α,β-Desaturation of Carbonyl Compounds Applicable to Cyclohexanones
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Direct selective desaturation of carbonyl compounds to synthesize α,β-unsaturated carbonyl compounds represents an environmentally benign alternative to classical stepwise procedures. In this study, we designed an ideal CeO2-supported Pd(II)-on-Au nanoparticle catalyst (Pd/Au/CeO2) and successfully achieved heterogeneously catalyzed selective desaturation of cyclohexanones to cyclohexenones using O2 in air as the oxidant. Besides cyclohexenones, various bioactive enones can also be synthesized from the corresponding saturated ketones under open air conditions in the presence of Pd/Au/CeO2. Preliminary mechanistic studies revealed that α-C-H bond cleavage in the substrates is the turnover-limiting step of this desaturation reaction.
- Jin, Xiongjie,Mizuno, Noritaka,Takei, Daisuke,Yabe, Tomohiro,Yamaguchi, Kazuya,Yatabe, Takafumi
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p. 5057 - 5063
(2020/05/27)
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- Synthetic method and application of indolizine compounds
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A synthetic method of the indolizine compound comprises the following steps: mixing a benzopyrone derivative, a bromopyridinium salt derivative, alkali and a solvent in a 10ml round-bottom flask, andstirring the mixture for 2-48 hours at the temperature of 25 DEG C and 100 DEG C; after the reaction is finished, purifying the crude product through silica gel chromatography to obtain a target compound with a structural formula shown as the formula I.
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Paragraph 0034-0037
(2020/11/26)
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- Synthesis of Flavanones via Palladium(II)-Catalyzed One-Pot β-Arylation of Chromanones with Arylboronic Acids
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A total of 47 flavanones were expediently synthesized via one-pot β-arylation of chromanones, a class of simple ketones possessing chemically unactivated β sites, with arylboronic acids via tandem palladium(II) catalysis. This reaction provides a novel route to various flavanones, including natural products such as naringenin trimethyl ether, in yields up to 92percent.
- Cho, Yang Yil,Jang, Hyu Jeong,Kim, Dong Hwan,Kim, Nam Yong,Kim, Nam-Jung,Kim, Young Min,Lee, Soo Jin,Lee, Yong Sup,Park, Boyoung Y.,Son, Seung Hwan,Yoo, Hyung-Seok
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p. 10012 - 10023
(2019/08/30)
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- Synthesis of α,β-dibromo ketones by photolysis of α-bromo ketones with N-bromosuccinimide: Photoinduced β-bromination of α-bromo ketones
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Irradiation of α-bromopropiophenones in the presence of NBS results in the formation of α,β-dibromopropiophenones, which can be viewed as β-bromination of α-bromopropiophenones. The reaction is believed to go through a series of reactions; photoinduced C–Br bond cleavage, elimination of HBr to give α,β-unsaturated ketone intermediates, and addition of Br2, which are formed by the reaction between HBr and NBS. From mechanistic studies of the reaction, we have also found a very convenient method for α-debromination of the α,β-dibromopropiophenones which is by simple irradiation of the dibromo ketones in acetone or 2-propanol without the use of any additives. Our results demonstrate that bromine can be added into or eliminated from the alpha, beta, or both positions to the carbonyl group by photochemical methods, which make synthetic options of bromine containing carbonyl compounds versatile.
- Moon, Da Yoon,An, Sejin,Park, Bong Ser
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- Enantioselective Total Syntheses of Pallambins A–D
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The first enantioselective total syntheses of (?)-pallambins A–D have been achieved in 15 or 16 steps from a known chiral cyclohexenone. Salient features of the syntheses include a palladium-catalyzed oxidative cyclization to assemble the [3.2.1]bicyclic moiety, an Eschenmoser–Claisen rearrangement/lactone formation sequence to construct the C ring, an intramolecular Wittig reaction to form the D ring, and individual transformations of pallambins C and D to generate pallambins A and B. The described synthesis avoids protecting-group manipulations through the design of highly chemo- and stereoselective transformations. During the course of this work, a palladium-catalyzed method for the dehydrobromination of α-bromoketones was developed, and the scope of this transformation was also investigated.
- Zhang, Xiwu,Cai, Xinxian,Huang, Bin,Guo, Lei,Gao, Zhongrun,Jia, Yanxing
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p. 13380 - 13384
(2019/08/16)
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- B(C6F5)3-catalyzed divergent cyanosilylations of chromones dependent on temperature
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A B(C6F5)3-catalyzed divergent cyanosilylation of chromones has been successfully realized. A variety of 4-oxochromane-2-carbonitriles were furnished as kinetic products in high yields via 1,4-cyanosilylations. An unexpected C-O bond cyanosilylation was achieved when the temperature was raised to 80 °C, affording 4-oxo-4-(2-hydroxylphenyl)but-2-enenitriles as thermodynamic products in 72-94% yields, which was confirmed by DFT results.
- Wang, Qiaotian,Feng, Xiangqing,Meng, Wei,Du, Haifeng
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p. 8354 - 8357
(2019/09/30)
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- Substituent-Oriented Synthesis of Substituted Pyrazoles/Chromeno[3,2- c]pyrazoles via Sequential Reactions of Chromones/3-Chlorochromones and Tosylhydrazones
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A facile and efficient synthetic strategy for the chemoselective synthesis of monocyclic/tricyclic-fused pyrazoles was developed, and it was oriented by different 3-position substituents (H or Cl) on the chromones. The reaction proceeded in a one-pot sequential way with a broad substrate scope and moderate to excellent yields.
- Dai, Tianzi,Li, Qunyi,Zhang, Xiaofei,Yang, Chunhao
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p. 5913 - 5921
(2019/05/10)
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- T3P mediated domino C(sp2)-H sulfenylation/annulation of enaminones and methylsulfinyls for the synthesis of chromone thioether derivatives
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A new regioselective method for the synthesis of 3-(methylthio)-4H-chromen-4-one and 3-(phenylthio)-4H-chromen-4-one derivatives has been developed. The reaction between o-hydroxy-phenyl-functionalized enaminones and methylsulfinyl derivatives using T3P gave good yields of chromone thioether derivatives. The reaction proceeds via domino chromone ring construction and C(sp2)-H bond sulfenylation under transition-metal-free conditions.
- Balakrishna,Gudipati, Ramakrishna,Kandula, Venu,Yennam, Satyanarayana,Uma Devi,Behera, Manoranjan
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p. 2458 - 2463
(2019/02/14)
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- Selectfluor-Mediated Tandem Cyclization of Enaminones for the Synthesis of 3-Fluorochromones
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An efficient synthesis of various 3-fluorochromones (3-fluoro-4 H -chromene-4-ones) from enamino ketones by using Selectfluor is described. The key step in the synthesis involves tandem fluorination and cyclization to form 3-fluorochromones in good yields. The significant features of this method include simple operational procedures, a high purity of the product, and excellent regioselectivity.
- Behera, Manoranjan,Chatterjee, Anindita,Kandula, Venu,Mallesham, Poosa,Raghavulu, K.,Thota, Pradeep Kumar,Yennam, Satyanarayana
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p. 2295 - 2299
(2019/12/11)
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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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- Unusual behavior of 3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one towards some phosphorus reagents: Synthesis of novel diethyl 2-phosphonochromone, diethyl 3-phosphonopyrone and 1,3,2-oxathiaphosphinines
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The chemical reactivity of 3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one (1) towards some phosphorus reagents was studied. The enaminone 1 was cyclized into diethyl 2-phosphonochromone 2 via its treatment with diethyl phosphite in basic medium. However, its reaction with triethoxy phosphonoacetate gave the substituted pyrone phosphonate 3. In addition, two novel examples of 4-(dimethylamino)-6-(2-hydroxyphenyl)-2-sulfido-4H-1,3,2-oxathia-phosphinines 6 and 7 were obtained from treatment of enaminone 1 with O,O-diethyl dithiophosphoric acid and Lawesson’s reagent. When enaminone 1 was also treated with phosphorus decasulfide, it was turned into 4H-thiochromene-4-thione while its treatment with phosphorus tribromide, phosphorus oxychloride, or phenylphosphonic dichloride, 4H-4-oxo-chromene was isolated in all cases. The possible reaction mechanisms of the formation of these products were discussed. The structures of newly isolated products were established by elemental analysis and spectral tools.
- Ali, Tarik E.,Assiri, Mohammed A.,Yahia, Ibrahim S.,Zahran, Heba Y.
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supporting information
p. 550 - 557
(2019/01/19)
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- Synthesis of 3-(N-arylcarbamoyl)chromones from 2-hydroxyarylaminoenones and isocyanates
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A new method for the synthesis of 2-unsubstituted and 2-substituted 3-(N-arylcarbamoyl)-chromones by the reaction of 3-dimethylamino-1-(2-hydroxyaryl)prop-2-en-1-ones with arylisocyanates has been proposed.
- Myannik,Semenova,Yarovenko,Krayushkin
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p. 104 - 109
(2019/04/25)
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- Synthesis of Enones and Enals via Dehydrogenation of Saturated Ketones and Aldehydes
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A general, efficient and economic palladium-catalyzed dehydrogenation to form enones or enals has been developed. The approach possesses extremely broad substrate scope including various linear or cyclic saturated ketones and aldehydes. The protocol is ligand-free, and molecular oxygen is used as the sole clean oxidant in the reaction. Due to mild reaction conditions, good functional group compatibility, and versatile utilities of enones and enals, the method can be applied in the late-stage synthesis of natural products, pharmaceuticals and fine chemicals. (Figure presented.).
- Pan, Gao-Fei,Zhu, Xue-Qing,Guo, Rui-Li,Gao, Ya-Ru,Wang, Yong-Qiang
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p. 4774 - 4783
(2018/11/10)
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- Solvent free, light induced 1,2-bromine shift reaction of α-bromo ketones
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Photolysis of α-bromopropiophenones in acetonitrile results in formation of β-bromopropiophenones with good product selectivity, which can be coined as 1,2-Br shift reaction. The product selectivity increases when the reaction is done in neat or solid state, where only the 1,2-Br shift product is formed in some cases. The reaction is suggested to proceed by C–Br bond homolysis to give a radical pair, followed by disproportionation and conjugate addition of HBr to the α,β-unsaturated ketone intermediate. When the unsaturated intermediate is stabilized by an extra conjugation, the reaction stops at the stage, in which the unsaturated ketone becomes a major product. The synthetic method described in this research fits in a category of eco-friendly organic synthesis nicely since the reaction does not use volatile organic solvents and any other additives such as acid, base or metal catalysts, etc. Besides, the method fits into perfect atom economy, which does not give any side products. The synthetic method should find much advantage over other alternative methods to obtain β-bromo carbonyl compounds.
- An, Sejin,Moon, Da Yoon,Park, Bong Ser
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p. 6922 - 6928
(2018/10/24)
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- Synthesis of chiral chromanols: Via a RuPHOX-Ru catalyzed asymmetric hydrogenation of chromones
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Chiral chromanols and their derivatives have been synthesized via a RuPHOX-Ru catalyzed asymmetric hydrogenation of chromones in high yields, >20:1 drs and with up to 99.9% ee. Control experiments show that the reaction undergoes two sequential asymmetric hydrogenation steps of the CC and CO double bonds. The reaction could be performed on a gram-scale with a relatively low catalyst loading (up to 1000 S/C), and the resulting products can be transformed to several biologically active compounds.
- Ma, Yujie,Li, Jing,Ye, Jianxun,Liu, Delong,Zhang, Wanbin
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supporting information
p. 13571 - 13574
(2019/01/05)
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- One-Pot Catalytic Cleavage of C=S Double Bonds by Pd Catalysts at Room Temperature
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The C=S double bonds in CS2 and thioketones were catalytically cleaved by Pd dimeric complexes [(N∧N)2Pd2(NO3)2](NO3)2 (N∧N, 2,2′-bipyridine, 4,4′-dimethylbipyridine or 4,4′-bis(trifluoromethyl)) at room temperature in one pot to afford CO2 and ketones, respectively, for the first time. The mechanisms were fully investigated by kinetic NMR, isotope-labeled experiments, in situ ESI-MS, and DFT calculations. The reaction is involved a hydrolytic desulfurization process to generate C=O double bonds and a trinuclear cluster, which plays a pivotal role in the catalytic cycle to regenerate the dimeric catalysts with HNO3. Furthermore, the electronic properties of catalyst ligands possess significant influence on reaction rates and kinetic parameters. At the same temperature, the reaction rate is consistent with the order of electronegativity of N∧N ligands (4,4′-bis(trifluoromethyl) > 2,2′-bipyridine > 4,4′-dimethylbipyridine). This homogeneous catalytic reaction features mild conditions, a broad substrate scope, and operational simplicity, affording insight into the mechanism of catalytic activation of carbon sulfur bonds.
- Zhu, Ting,Wu, Xiaoxi,Yang, Xinzheng,Sharma, Bigyan,Li, Na,Huang, Jiaming,Wang, Wentao,Xing, Wang,Zhao, Zhenwen,Huang, Hui
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supporting information
p. 9266 - 9273
(2018/08/17)
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- Natural products as sources of new fungicides (V): Design and synthesis of acetophenone derivatives against phytopathogenic fungi in vitro and in vivo
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A series of acetophenone derivatives (10a–10i, 11, 12a–12g, 13a–13g, 14a–14d and 15a–15l) were designed, synthesized and evaluated for antifungal activities in vitro and in vivo. The antifungal activities of 53 compounds were tested against several plant pathogens, and their structure–activity relationship was summarized. Compounds 10a–10f displayed better antifungal effects than two reference fungicides. Interestingly, the most potent compound 10d exhibited antifungal properties against Cytospora sp., Botrytis cinerea, Magnaporthe grisea, with IC50 values of 6.0–22.6 μg/mL, especially Cytospora sp. (IC50 = 6.0 μg/mL). In the in vivo antifungal assays, 10d displayed the significant protective efficacy of 55.3% to Botrytis cinerea and 73.1% to Cytospora sp. The findings indicated that 10d may act as a potential pesticide lead compound that merits further investigation.
- Dan, Wen-Jia,Tuong, Thi-Mai-Luong,Wang, Da-Cheng,Li, Ding,Zhang, An-Ling,Gao, Jin-Ming
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supporting information
p. 2861 - 2864
(2018/07/25)
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- Metalated Chromene and Chromone Complexes: pH Switchable Metal–Carbon Bonding Interaction, Photo-triggerable Chromone Delivery Application, and Antioxidative Activity
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The two families of RuII-chromene and -chromone complexes isolated in this work represent the first examples of metalated chromene and chromone complexes synthesized through transition-metal-mediated cyclization of phenol-tethered ynone. These unprecedented metalated heterocyclic compounds exhibit remarkable features, such as pH-switchable metal–carbon bonding interactions, photo-triggerable release of organic chromone upon visible-light irradiation, and superior antioxidative property to their organic analogue (1,4-benzopyrone). These findings not only offer mechanistic insights into metal-induced activation of functionalized alkynes, but also add a new dimension to rational design of antioxidants and photo-responsive drug delivery systems.
- Ng, Sze-Wing,Chung, Lai-Hon,Yeung, Chi-Fung,Lo, Hoi-Shing,Shek, Hau-Lam,Kang, Tian-Shu,Leung, Chung-Hang,Ma, Dik-Lung,Wong, Chun-Yuen
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p. 1779 - 1783
(2018/02/10)
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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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p. 153 - 160
(2017/11/23)
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- A flavonoid compound and its preparation method and application (by machine translation)
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A flavonoid compound and its preparation method and application, relates to an anti-tumor compound. The class flavone compounds for the treatment of cancer (including liver cancer, cervical cancer and lung cancer) in the medicament of the application. The compounds are new compounds of structure, creative and obviously the practicability of the anti-tumor effect, can be used as a potential drug development application. (by machine translation)
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Paragraph 0042; 0051-0053
(2018/03/26)
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- An Efficient Microwave-Assisted Propylphosphonic Anhydride (T3P )-Mediated One-Pot Chromone Synthesis via Enaminones
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An efficient synthesis of 4 H -chromene-4-ones via enamino ketones, with cyclization by using T3P under microwave heating is described. This is the first report for the synthesis of chromones by using T3P . Significant features of this method include short reaction times and high-purity products.
- Balakrishna,Kandula, Venu,Gudipati, Ramakrishna,Yennam, Satyanarayana,Devi, P. Uma,Behera, Manoranjan
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supporting information
p. 1087 - 1091
(2018/04/30)
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- Pot-economic synthesis of diarylpyrazoles and pyrimidines involving Pd-catalyzed cross-coupling of 3-trifloxychromone and triarylbismuth
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Abstract: The present study reveals the formation of 3,4-diarylpyrazole and 4,5-diarylpyrimidine in one-pot operation starting from 3-trifloxychromone and triarylbismuth. The complete process encompasses two steps in the one-pot operation. The first step leads to the formation of isoflavone via cross-coupling reaction of 3-trifloxychromone and triarylbismuth as a threefold arylating reagent. These isoflavones were further converted into 3,4-diarylpyrazole and 4,5-diarylpyrimidine using hydrazine hydrate and guanidinium chloride in the successive step in the same pot. Interestingly the formation of 3,4-diarylpyrazole was achieved in the shortest reaction time i.e., 30 min that too at room temperature. Overall the developed methodology provides easy access to the medicinally important diarylpyrazole and pyrimidine moiety in one-pot operation and in short reaction time. Graphical Abstract: Synopsis The work presented here describes the novel methodology for the formation of medicinally important heterocycles 3,4-diarylpyrazole and 4,5-diarylpyrimidine in one-pot operation starting from 3-trifloxychromone and triarylbismuth.
- Kumar, Abhijeet,Rao, Maddali L N
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- Mn(OAc)3-Promoted Oxidative Csp3-P Bond Formation through Csp2-Csp2 and P-H Bond Cleavage: Access to β-Ketophosphonates
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The Mn(OAc)3-promoted oxidative phosphonylation of N,N-dimethylenaminones with H-phosphonates, involving a chemo- and regioselective Csp2-Csp2 bond cleavage and Csp3-P bond formation in one step, provided successfully functionalized β-ketophosphonates under mild reaction conditions. Oxidative Csp3-H/P-H cross-coupling reactions via Csp3-C(C=O) bond cleavage and mechanistic studies are conducted preliminarily, and a possible mechanism is proposed. This novel method proceeds in good to excellent yields, shows operational simplicity, broad substrate scope, and large-scale preparation.
- Zhou, Pan,Hu, Biao,Li, Lingdan,Rao, Kairui,Yang, Jiao,Yu, Fuchao
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p. 13268 - 13276
(2017/12/26)
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- Ag(i)/persulfate-catalyzed decarboxylative coupling of α-oxocarboxylates with organotrifluoroborates in water under room temperature
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The decarboxylative coupling reaction of α-oxocarboxylates and organotrifluoroborates was carried out smoothly in the presence of catalytic AgNO3 using K2S2O8 as oxidant to generate diarylketone products in high
- Chang, Sheng,Wang, Jian Feng,Dong, Lin Lin,Wang, Dan,Feng, Bo,Shi, Yuan Tai
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p. 51928 - 51934
(2017/11/22)
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- Unified Approach to (Thio)chromenones via One-Pot Friedel-Crafts Acylation/Cyclization: Distinctive Mechanistic Pathways of β-Chlorovinyl Ketones
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A facile synthetic method to chromenones and thiochromenones has been developed using a one-pot Friedel-Crafts acylation of alkynes with suitably substituted benzoyl chlorides. This unified approach to (thio)chromenones is readily applicable to aryl- and alkylalkynes where the stereochemically well-defined β-chlorovinyl ketone intermediates undergo distinctively different cyclization pathways. The ready availability of both starting materials, alkynes and benzoyl chlorides, coupled with the experimental simplicity makes the current synthetic method to (thio)chromenones fast, efficient, and practical.
- Kim, Hun Young,Song, Eunsun,Oh, Kyungsoo
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supporting information
p. 312 - 315
(2017/04/21)
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- Transition-metal-free synthesis of 3-sulfenylated chromones via KIO3-catalyzed radical C(sp2)–H sulfenylation
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The reactions between o-hydroxylphenyl-functionalized enaminones and sulfonyl hydrazines providing 3-sulfenylated chromones via domino chromone ring construction and C(sp2)–H bond sulfenylation have been achieved under transition-metal-free conditions by using KIO3 as the only catalyst.
- Guo, Yanhui,Zhong, Shanshan,Wei, Li,Wan, Jie-Ping
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supporting information
p. 2017 - 2022
(2017/10/16)
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- Gold nanoparticles on OMS-2 for heterogeneously catalyzed aerobic oxidative α,β-dehydrogenation of β-heteroatom-substituted ketones
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In the presence of Au nanoparticles supported on manganese oxide OMS-2 (Au/OMS-2), various kinds of β-heteroatom-substituted α,β-unsaturated ketones (heteroatom = N, O, S) can be synthesized through α,β-dehydrogenation of the corresponding saturated ketones using O2 (in air) as the oxidant. The catalysis of Au/OMS-2 is truly heterogeneous, and the catalyst can be reused.
- Yoshii, Daichi,Jin, Xiongjie,Yatabe, Takafumi,Hasegawa, Jun-ya,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information
p. 14314 - 14317
(2016/12/14)
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- Catalytic One-Pot Diastereoselective Michael-Initiated Ring-Closure of Methyl Ketones with 3-Bromochromones: Synthesis of Cyclopropa[b]chromanones
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A one-pot diastereoselective base-catalyzed Michael-initiated ring-closure (MIRC) of activated methyl ketones with 3-bromochromones to give cyclopropa[b]chromanones is described. Three asymmetric centres are generated in the new cyclopropa[b]chromanone skeleton. Stereochemistry studies based on NMR spectroscopy and single-crystal X-ray diffraction analysis revealed the trans configuration of the cyclopropane ring, with the (1R,1aS,7aR)/(1S,1aR,7aS) pair of enantiomers, as was further confirmed by chiral HPLC. The use of acetone in our reaction produced a 1-acetyl-substituted cyclopropa[b]chromanone that can undergo a subsequent MIRC reaction with a second molecule of 3-bromochromone to give the first described 1,1′-carbonylbis(cyclopropa[b]chromanone) dimers as a meso form.
- Sousa, Joana L. C.,Talhi, Oualid,Mendes, Ricardo F.,Almeida Paz, Filipe A.,Bachari, Khaldoun,Silva, Artur M. S.
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p. 3949 - 3958
(2016/08/24)
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- A facile strategy for accessing 3-alkynylchromones through gold-catalyzed alkynylation/cyclization of o-hydroxyarylenaminones
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A strategy based on tandem alkynylation of o-hydroxyarylenaminones followed by intramolecular cyclization has been developed to generate a diverse array of 3-alkynyl chromones. The functionality embedded in these key intermediates enables their facile elaboration into more diverse structures by a variety of functionalizations and ring-forming processes.
- Akram, Manjur O.,Bera, Saibal,Patil, Nitin T.
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supporting information
p. 12306 - 12309
(2016/10/22)
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- One-pot synthesis of 3-(furan-2-yl)-4: H -chromen-4-ones from 1-(2-hydroxyphenyl)butane-1,3-diones and 2,5-dimethoxy-2,5-dihydrofuran catalyzed via K10 montmorillonite under solvent-free conditions
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A new, concise and efficient method of one-pot synthesis of 3-(furan-2-yl)-4H-chromen-4-ones was developed using K10 montmorillonite catalysis under solvent-free conditions. The procedure of the synthesis of 3-(furan-2-yl)-4H-chromen-4-ones was that 1-(2-hydroxyphenyl)butane-1,3-diones and 2,5-dimethoxy-2,5-dihydrofuran underwent a process of α-alkoxyalkylation in the presence of K10 montmorillonite at 80 °C for 0.5 h and continuously at 120 °C for another 0.5 h. The advantages of this method were that it was solvent-free, the K10 montmorillonite was recyclable and it had an easy work-up.
- Han, Jie,Wang, Tao,Feng, Siqi,Li, Chenchen,Zhang, Zunting
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p. 4092 - 4097
(2016/07/21)
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- One-Pot Synthesis of Benzopyran-4-ones with Cancer Preventive and Therapeutic Potential
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A one-pot synthesis of novel benzopyran-4-ones is described. In a tandem reaction, organobase-catalysed Michael addition of R1COCH2COR2 on chromone-3-carboxylic acid led to decarboxylation and pyran-4-one ring opening of the latter. This was followed by chromone-and/or chromanone ring closure of the resulting Michael adducts when R1 is an ortho-hydroxyaryl group. Antioxidant testing of 14 derivatives identified strong antiradical properties of chromanones 3o-r (2.1-3.1 μmol Trolox equiv./μmol compound in the DPPH assay). Chromanones 3p and 3r and 2-styrylchromone 3k were also most potent in inducing the cytoprotective Keap1-Nrf2 signalling pathway in a reporter gene assay (fivefold induction at concentrations 3 μM). Of the seven compounds evaluated for antiproliferative activities, 3k and 3r were the most active, inhibiting leukaemia K562 cell proliferation by 50 % after 72 h at concentrations of 4.5 and 7.9 μM, whereas normal peripheral blood mononuclear cells were not affected. Chromanones 3p and 3r and 2-styrylchromones 3k potently activate the Nrf2 response in the AREc32 cell line at low micromolar concentrations (C5 3 μM). Compounds 3k and 3r are also the most active in inhibiting cell proliferation by 50 % after 72 h incubation at concentrations of 4.5 and 7.7 μM, whereas normal peripheral blood mononuclear cells were not affected.
- Talhi, Oualid,Brodziak-Jarosz, Lidia,Panning, Jana,Orlikova, Barbora,Zwergel, Clemens,Tzanova, Tzvetomira,Philippot, Stéphanie,Pinto, Diana C. G. A.,Paz, Filipe A. Almeida,Gerhaüser, Clarissa,Dick, Tobias P.,Jacob, Claus,Diederich, Marc,Bagrel, Denyse,Kirsch, Gilbert,Silva, Artur M. S.
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supporting information
p. 965 - 975
(2016/03/01)
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- TMSI-Promoted vinylogous michael addition of siloxyfuran to 2-substituted chromones: A general approach for the total synthesis of chromanone lactone natural products
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A concise and facile synthetic protocol for the construction of the 2-γ-lactone chromanone skeleton has been achieved through a TMSI-promoted diastereoselective vinylogous Michael addition of siloxyfuran to 2-substituted chromones. The applicability of this method is demonstrated through the rapid access to the total syntheses of (±)-microdiplodiasone, (±)-lachnone C, and (±)-gonytolides C and G.
- Liu, Jie,Li, Zhanchao,Tong, Pei,Xie, Zhixiang,Zhang, Yuan,Li, Ying
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supporting information
p. 1632 - 1643
(2015/02/19)
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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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supporting information
p. 777 - 784
(2016/01/12)
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- Rhodium/chiral diene-catalyzed asymmetric 1,4-addition of arylboronic acids to chromones: A highly enantioselective pathway for accessing chiral flavanones
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Chromone has been noted to be one of the most challenging substrates in the asymmetric 1,4-addi-tion of α,β-unsaturated carbonyl compounds. By employing the rhodium complex associated with a chiral diene ligand, (R,R)-Ph-bod, the 1,4-addition of a variety of aryl-boronic acids was realized to give high yields of the corresponding flavanones with excellent enantioselectivities (≥97% ee, 99% ee for most substrates). Ring-opening side products, which would lead to erosion of product enantioselectivity, were not observed under the stated reaction conditions.
- He, Qijie,Wang, Jun,So, Chau Ming,Hayashi, Tamio,Bian, Zhaoxiang
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supporting information
p. 540 - 543
(2015/05/05)
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- FeCl3 and ether mediated direct intramolecular acylation of esters and their application in efficient preparation of xanthone and chromone derivatives
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The direct intramolecular acylation of esters was developed by using the combined system of FeCl3 with Cl2CHOCH3. This unique cooperative system offered a new and efficient approach to biologically important xanthone and chromone derivatives with regioselectivity. Examples were reported, and control experiments were carried out to examine the effect of the benzyl esters and Cl2CHOCH3.
- Jiang, Neng,Li, Su-Yi,Xie, Sai-Sai,Yao, Hequan,Sun, Hongbin,Wang, Xiao-Bing,Kong, Ling-Yi
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p. 63632 - 63641
(2015/02/19)
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- Recyclable and reusable PdCl2(PPh3) 2/PEG-2000/H2O system for the carbonylative Sonogashira coupling reaction of aryl iodides with alkynes
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PdCl2(PPh3)2 in a mixture of water and poly(ethylene glycol) (PEG-2000) is shown to be an extremely active catalyst for the carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes. The reaction can be conducted under an atmospheric pressure of carbon monoxide at 25 °C with Et3N as a base, yielding a variety of alkynyl ketones in good to excellent yields. Application of this synthetic method to prepare flavones from o-iodophenol and terminal alkynes was also achieved. The isolation of the products is readily achieved by extraction with diethyl ether, and the PdCl2(PPh3)2/PEG-2000/ H2O system can be easily recycled and reused six times without any loss of catalytic activity. the Partner Organisations 2014.
- Zhao, Hong,Cheng, Mingzhu,Zhang, Jiatao,Cai, Mingzhong
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supporting information
p. 2515 - 2522
(2014/05/06)
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- Intermolecular C-O addition of carboxylic acids to arynes: Synthesis of o-hydroxyaryl ketones, xanthones, 4-chromanones, and flavones
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An efficient and simple route to biologically and pharmaceutically important o-hydroxyaryl ketones, xanthones, 4-chromanones, and flavones has been developed utilizing readily available carboxylic acids and commercially available o-(trimethylsilyl)aryl tr
- Dubrovskiy, Anton V.,Larock, Richard C.
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p. 2789 - 2798
(2013/03/29)
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- Synthesis, docking study and relaxant effect of 2-alkyl and 2-naphthylchromones on rat aorta and guinea-pig trachea through phosphodiesterase inhibition
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Chromone (4), which form the base structure of various flavonoids isolated as natural products, is capable of relaxing smooth muscle. This is relevant to the treatment of high blood pressure, asthma and chronic obstructive pulmonary disease. The former disorder involves the contraction of vascular smooth muscle (VSM), and the latter two bronchoconstriction of airway smooth muscle (ASM). One of the principal mechanisms by which flavonoids relax muscle tissue is the inhibition of phosphodiesterases (PDEs), present in both VSM and ASM. Therefore, a study was designed to analyze the structure-activity relationship of chromone derivatives in vaso- and bronchorelaxation through the inhibition of PDE. Docking studies showed that these chromones bind at the catalytic site of PDEs. Consequently, we synthesized analogs of chromones substituted at position C-2 with alkyl and naphthyl groups. These compounds were synthesized from 2-hydroxyacetophenone and acyl chlorides in the presence of DBU and pyridine, modifying the methodology reported for the synthesis of 3-acylchromones by changing the reaction temperature from 80 to 30°C and using methylene chloride as solvent, yielding the corresponding phenolic esters 10a-10h. These compounds were cyclized with an equivalent of DBU, pyridine as solvent, and heated at reflux temperature, yielding the chromones 11a-11h. Evaluation of the vasorelaxant effect of 4, 11a-11h on rat aorta demonstrated that potency decreases with branched alkyl groups. Whereas the EC50 of compound 11d (substituted by an n-hexyl group) was 8.64 ± 0.39 μM, that of 11f (substituted by an isobutyl group) was 14.58 ± 0.64 μM. Contrarily, the effectiveness of the compound is directly proportional to the length of the alkyl chain, as evidenced by the increase in maximal effect of compound 11c versus 11d (66% versus 100%) and 11e versus 11f (60% versus 96%). With an aromatic group like naphthyl as the C-2 substituent, the effectiveness was only 43%. All compounds tested on guinea pig trachea showed less than 55% effectiveness. Compounds 4, 11a-11h were evaluated as PDE inhibitors in vitro, with 11d showing the greatest effect (73%), corroborating the importance of a long alkyl chain, which inhibits the decomposition of cGMP. Docking studies showed that the compound 11d was selective for the inhibition of PDE-5.
- Rodriguez-Ramos, Fernando,Navarrete, Andres,Gonzalez-Andrade, Martin,Alarcon, Carlos,Aguilera-Cruz, Alejandro,Reyes-Ramirez, Adelfo
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- Practical metal- and additive-free methods for radical-mediated reduction and cyclization reactions
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Two facile, metal- and additive-free protocols for radical dehalogenation, deoxygenation and cyclization reactions are reported. Irradiation by household fluorescent light bulbs or the presence of an air atmosphere is shown to initiate the desired reactions, thus providing highly practical reaction setups for radical-mediated reductions and cyclizations.
- Jiang, Hao,Bak, Jesper R.,Lopez-Delgado, Francisco Javier,Jorgensen, Karl Anker
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supporting information
p. 3355 - 3359
(2013/12/04)
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- Synthesis of chromone, quinolone, and benzoxazinone sulfonamide nucleosides as conformationally constrained inhibitors of adenylating enzymes required for siderophore biosynthesis
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MbtA catalyzes the first committed step of mycobactin biosynthesis in Mycobacterium tuberculosis (Mtb) and is responsible for the incorporation of salicylic acid into the mycobactin siderophores. 5′-O-[N-(Salicyl) sulfamoyl]adenosine (Sal-AMS) is an extremely potent nucleoside inhibitor of MbtA that possesses excellent activity against whole-cell Mtb but suffers from poor bioavailability. In an effort to improve the bioavailability, we have designed four conformationally constrained analogues of Sal-AMS that remove two rotatable bonds and the ionized sulfamate group on the basis of computational and structural studies. Herein we describe the synthesis, biochemical, and microbiological evaluation of chromone-, quinolone-, and benzoxazinone-3- sulfonamide derivatives of Sal-AMS. We developed new chemistry to assemble these three heterocycles from common β-ketosulfonamide intermediates. The synthesis of the chromone- and quinolone-3-sulfonamide intermediates features formylation of a β-ketosulfonamide employing dimethylformamide dimethyl acetal to afford an enaminone that can react intramolecularly with a phenol or intermolecularly with a primary amine via addition-elimination reaction(s). The benzoxazinone-3-sulfonamide was prepared by nitrosation of a β-ketosulfonamide followed by intramolecular nucleophilic aromatic substitution. Mitsunobu coupling of these bicyclic sulfonamides with a protected adenosine derivative followed by global deprotection provides a concise synthesis of the respective inhibitors.
- Engelhart, Curtis A.,Aldrich, Courtney C.
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p. 7470 - 7481
(2013/09/02)
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- A mild and efficient protocol to synthesize chromones, isoflavones, and homoisoflavones using the complex 2,4,6-trichloro-1,3,5-triazine/ dimethylformamide
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A mild and efficient one-flask method has been developed for the synthesis of chromones, isoflavones, and homoisoflavones from 2-hydroxyacetophenones, deoxybenzoins, and dihydrochalcones, respectively, via one-carbon extension using the complex 2,4,6-trichloro-1,3,5-triazine/dimethylformamide. Deoxybenzoins and dihydrochalcones were prepared in situ by the reaction of readily available substituted phenols with phenylacetic acids and 3-phenylpropanoic acids, respectively. This method allows the synthesis of a wide range of compounds with multiple phenolic hydroxyls and other substituents. The methodology has been applied to the synthesis of three naturally occurring isoflavones such as formononetin (9c), daidzein (9d), and retusin (9h).
- Basha, G. Mahaboob,Yadav, S. Kumar,Srinuvasarao,Prasanthi,Ramu,Mangarao,Siddaiah
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p. 763 - 768
(2013/08/23)
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