- Synthesis and chemical transformations of partially hydrogenated [1,2,4]triazolo[5,1-b]quinazolines
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The reaction of 5-methyl-7-phenyl-4,7-dihydro-1,2,4-triazolo[1,5-a] pyrimidine with α,β-unsaturated carbonyl compounds in MeOH in the presence of MeONa affords partially hydrogenated aryl-substituted [1,2,4]triazolo[5,1-b]quinazolines. Hydrolysis, oxidati
- Lipson,Desenko,Ignatenko,Shishkin,Shishkina
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- New synthetic methodology utilising 1,2-dioxines and stabilised phosphorus ylides: A highly diastereoselective cyclopropanation reaction
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A new method is described for the synthesis of diastereomerically pure cyclopropanes from substituted 1,2-dioxines 1a-c and stabilised phosphorus ylides 2a-e.
- Avery, Thomas D.
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- Mechanistic investigations on the reaction between 1,2-dioxines and bulky stabilized phosphorus ylides: An efficient route to closely related cyclopropane stereoisomers
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The bulky stabilized ylides (2a-d) react with a range of 1,2-dioxines (1a-d) to afford the diversely functionalized cyclopropanes 7 in excellent yield and diastereomeric excess. This is in direct contrast to the situation when nonbulky ester ylides are utilized which results in a completely different cyclopropyl series. Through a combination of isolation, spectroscopic, temperature, and deuterium and additive effects studies, the mechanism of cyclopropane formation from this second pathway can be proposed. Importantly, enolate quenching of the intermediate 1-2λ5-oxaphospholanes 4 prior to collapse results in an equilibrium mixture of intermediates 10 and 11 which have been fully characterized, and their formation is primarily a result of the steric bulk of the stabilized ester ylide. These intermediates (10/11) then collapse further and result in formation of the observed closely related cyclopropyl stereoisomers 7 and 8. Moreover, the addition of LiBr to these reactions allows for the control of which of the two possible cyclopropanation pathways will be dominant. Finally, optimal protocols that demonstrate the potential of this new cyclopropanation methodology for the ready construction of closely related cyclopropyl stereoisomers are presented.
- Avery, Thomas D.,Fallon, Gary,Greatrex, Ben W.,Pyke, Simon M.,Taylor, Dennis K.,Tiekink, Edward R. T.
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- Intermolecular Photoredox Coupling: Alternative to Norrish Type II Reaction and Yang Cyclization in Ketones with γ-C?H Bonds
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A new reaction pathway for the photoconversion of butyrophenone in acetonitrile was investigated. In addition to the classic intramolecular photoreactivity of ketones with γ-C?H bonds (Norrish type II fragmentation and Yang cyclization), intermolecular generated species were isolated and characterized: 1,2-Dibenzoylethane, 2-phenacylacetonitrile (oxidized species) and pinacols (reduced species). They account for approx. 20 % of the converted starting material, similar to the Yang product. The acetophenone enol intermediate, formed in situ via the Norrish type II reaction, has been identified as an H-atom donor for the main intermolecular reaction steps, and has been distinguished from other conceivable mechanistic possibilities. Experimental results with analogue compounds suggest that the intermolecular product formation pathway may be of general relevance.
- Hoffmann, Heiko,Tausch, Michael W.
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- Exploitation of ylide steric bulk to alter cyclopropanation outcome during the reaction of 1,2-dioxines and stabilised phosphorus ylides
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The exploitation of ylide steric bulk to alter cyclopropanation outcome during the reaction of 1,2-dioxines and stabilised phosphorus ylides was discussed. It was found that sterically bulky ylides favoured the formation of a different distereomeric cyclopropyl series at ambient temperatures. The analysis showed that the use of sterically bulky ester ylides under concentrated conditions favoured the formation of the 'normal' trans isomer.
- Avery, Thomas D.,Greatrex, Ben W.,Taylor, Dennis K.,Tiekink, Edward R.T.
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- Enantioselective Stetter Reactions Catalyzed by Bis(amino)cyclopropenylidenes: Important Role for Water as an Additive
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The first highly enantioselective intermolecular Stetter reaction using simple enones is reported. A series of novel chiral BAC structures were designed and prepared. They were tested in the Stetter reaction with simple aldehydes and enones. The products were generated in excellent yields and enantioselectivities (up to 94% ee). Surprisingly, a substoichiometric amount of water was crucial to obtain high enantioselectivities. Chiral BACs were also shown to catalyze 1,6-conjugate addition reactions with paraquinone methides enantioselectively.
- Rezazadeh Khalkhali, Mehran,Wilde, Myron M. D.,Gravel, Michel
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supporting information
p. 155 - 159
(2021/01/09)
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- Synthesis of Unsymmetrical 1,4-Dicarbonyl Compounds by Photocatalytic Oxidative Radical Additions
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Herein we report a photocatalytic oxidative radical addition reaction for the synthesis of unsymmetrical 1,4-dicarbonyl compounds. This reaction utilizes a desulfurization process to generate electrophilic radicals, which add to α-halogenated alkenes and undergo further oxidation to deliver 1,4-dicarbonyl compounds. This mild and highly efficient method provides a valuable alternative to known strategies.
- Dong, Ya,Li, Ruining,Zhou, Junliang,Sun, Zhankui
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p. 6387 - 6390
(2021/08/23)
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- Aerobic Oxidative Dehydrogenation of Ketones to 1,4-Enediones
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An efficient and unprecedented strategy for the synthesis of 1,4-enediones from saturated ketones has been developed via palladium-catalyzed oxidative dehydrogenation. The protocol employs molecular oxygen as the sole oxidant and represents an atom- and step-economic process. The approach showed broad substrate scope, good functional group tolerance, and complete E-stereoselectivity. The reaction mechanism has been investigated through deuterium-labeling experiments and intermediate experiments.
- Zhao, Bao-Yin,Zhang, Xing-Long,Guo, Rui-Li,Wang, Meng-Yue,Gao, Ya-Ru,Wang, Yong-Qiang
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supporting information
p. 1216 - 1221
(2021/02/20)
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- Electrochemical reactivity of S-phenacyl-O-ethyl-xanthates in hydroalcoholic (MeOH/H2O 4:1) and anhydrous acetonitrile media
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The electrochemical behavior of a series of S-phenacyl-O-ethyl-xanthates (O-ethyl-dithiocarbonate acetophenone derivatives) in hydroalcoholic (MeOH/H2O 4:1) and anhydrous media (ACN/TBAPF6) using carbon electrodes was studied. Cyclic voltammetry showed in hydroalcoholic media only two cathodic waves, whereas in ACN one anodic and two cathodic waves were present. The first cathodic wave corresponded to the reduction of the phenylketone group, whereas the first anodic was attributed to the xanthate unit. Macroelectrolysis on graphite and vitreous carbon at anodic and cathodic potentials, let us to explore the synthetic potential of this electrochemical reactions. With some compounds in hydroalcoholic media and using carbon electrodes, polymeric material was deposited on the electrode impeding the reaction; this deposit was characterized by AFM and SEM-EDS. The electroreduction on Ti electrode overcome this problem and gave the corresponding acetophenones (>95%). On the other hand, in ACN, small quantities of the dimeric 1,4-dicarbonyl compounds X-PhCOCH2CH2COPh-X (7–15%), as well as the corresponding acetophenones (ca. 50%) were isolated. Oxidation macroelectrolysis showed a very complicated transformation without synthetic value. The reaction mechanism for the reduction and the homolytic dissociation into the phenacyl radical was supported by DFT calculations.
- López-López, Ernesto Emmanuel,López-Jiménez, Sergio J.,Barroso-Flores, Joaquín,Rodríguez-Cárdenas, Esdrey,Tapia-Tapia, Melina,López-Téllez, Gustavo,Miranda, Luis D.,Frontana-Uribe, Bernardo A.
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- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
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A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
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p. 2134 - 2141
(2021/09/29)
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- Bi(OTf)3-Mediated (4+1) Annulation of α-Sulfonyl o-Hydroxyacetophenones with α-Hydroxy Arylketones to Access Sulfonyl 2-Aroylbenzofurans
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In this paper, a high-yield, facile route for the scalable synthesis of sulfonyl 2-aroylbenzofurans via a Bi(OTf)3-mediated intermolecular double cyclocondensation of α-sulfonyl o-hydroxyacetophenones with substituted α-hydroxy arylketones under mild open-vessel reaction conditions is described. In the overall reaction, water is generated as the only byproduct. Various metal triflate-promoted reactions and conditions are investigated for the efficient one-pot (4+1) annulation reaction. (Figure presented.).
- Chang, Meng-Yang,Chen, Kuan-Ting
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p. 2594 - 2609
(2021/03/29)
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- Electrochemical and Photocatalytic Oxidative Coupling of Ketones via Silyl Bis-enol Ethers
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Diastereoselective oxidative coupling of ketones through a silyl bis-enol ether intermediate by anodic and photocatalytic oxidation is reported. These methods provide several 1,4-diketones in good yields without the need for stoichiometric metal oxidants. The strategic use of a silicon tether enables the coupling of both aromatic and aliphatic ketones as well as the synthesis of quaternary centers. Cyclic voltammetry is used to gain insight into the oxidation events of the reaction.
- Caravana, Aidan C.,Nagasing, Benjamin,Dhanju, Sandeep,Reynolds, Rebekah G.,Weiss, Emily A.,Thomson, Regan J.
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supporting information
p. 6600 - 6611
(2021/05/29)
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- Electrochemical α-Arylation of Ketones via Anodic Oxidation of in Situ Generated Silyl Enol Ethers
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An electrochemical procedure for the α-arylation of ketones has been developed. The method is based on the generation and one-pot anodic oxidation of silyl enol ethers in the presence of the arene. This strategy avoids isolation of the silyl enol intermediate and the utilization of external supporting electrolytes. Intermolecular arylations, which had not been reported so far, are possible when electron-rich arenes are utilized as coupling partners. The method has been demonstrated for a wide variety of aryl ketones and activated arenes, with moderate to good yields (up to 69%) obtained. Mechanistic insights and a theoretical rationale that explains the ketone α-arylation versus dimerization selectivity are also presented.
- Jud, Wolfgang,Sommer, Florian,Kappe, C. Oliver,Cantillo, David
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p. 16026 - 16034
(2021/08/24)
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- Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions
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The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.
- Chan, Kaai-Tung,Che, Chi-Ming,Du, Lili,Liu, Yungen,Phillips, David Lee,To, Wai-Pong,Tong, Glenna So Ming,Wu, Liang-Liang,Yu, Daohong
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p. 6370 - 6382
(2020/07/15)
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- Copper(I)/DDQ-Mediated Double-Dehydrogenative Diels-Alder Reaction of Aryl Butenes with 1,4-Diketones and Indolones
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A copper(I)/DDQ-mediated double-dehydrogenative Diels-Alder (DDDA) reaction of simple butenes with 1,4-diketones and indolones has been established for the first time. This strategy is based on a tandem double-dehydrogenation/Diels-Alder reaction from nonprefunctionalized starting materials, in which both a diene and dienophile were in situ generated via activation of fourfold inert C(sp3)-H bonds in one catalytic system.
- Chen, Jie,Hu, Wei,Wang, Min,Xu, Wen-Lei,Zhao, Wei-Ming,Zhou, Ling
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supporting information
p. 7169 - 7174
(2020/10/12)
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- Reduction of Activated Alkenes by PIII/PV Redox Cycling Catalysis
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The carbon–carbon double bond of unsaturated carbonyl compounds was readily reduced by using a phosphetane oxide catalyst in the presence of a simple organosilane as the terminal reductant and water as the hydrogen source. Quantitative hydrogenation was observed when 1.0 mol % of a methyl-substituted phosphetane oxide was employed as the catalyst. The procedure is highly selective towards activated double bonds, tolerating a variety of functional groups that are usually prone to reduction. In total, 25 alkenes and two alkynes were hydrogenated to the corresponding alkanes in excellent yields of up to 99 %. Notably, less active poly(methylhydrosiloxane) could also be utilized as the terminal reductant. Mechanistic investigations revealed the phosphane as the catalyst resting state and a protonation/deprotonation sequence as the crucial step in the catalytic cycle.
- Longwitz, Lars,Werner, Thomas
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supporting information
p. 2760 - 2763
(2020/02/05)
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- Synthesis of 1,4-Dicarbonyl Compounds by Visible-Light-Mediated Cross-Coupling Reactions of α-Chlorocarbonyls and Enol Acetates
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Herein, we report a protocol for visible-light-mediated radical coupling reactions of α-chloroketones and enol acetates to afford 1,4-dicarbonyl compounds, which are important precursors and intermediates in organic synthesis. The reaction involves photoredox-catalyzed activation of the α-chloroketone upon photoelectron transfer, carbon–chlorine bond cleavage, and coupling of the resulting radical with the carbon–carbon double bond of the enol acetate. This mild protocol has a wide substrate scope and moderate to good yields. (Figure presented.).
- Liu, Qiang,Wang, Rui-Guo,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
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p. 4391 - 4396
(2020/09/21)
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- Syntheses of Pyrroles, Pyridines, and Ketonitriles via Catalytic Carbopalladation of Dinitriles
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The first example of the Pd-catalyzed addition of organoboron reagents to dinitriles, as an efficient means of preparing 2,5-diarylpyrroles and 2,6-diarylpyridines, has been discussed here. Furthermore, the highly selective carbopalladation of dinitriles with organoboron reagents to give long-chain ketonitriles has been developed as well. Based on the broad scope of substrates, excellent functional group tolerance, and use of commercially available substrates, the Pd-catalyzed addition reaction of arylboronic acid and dinitriles is expected to be significant in future synthetic procedures.
- Qi, Linjun,Li, Renhao,Yao, Xinrong,Zhen, Qianqian,Ye, Pengqing,Shao, Yinlin,Chen, Jiuxi
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supporting information
p. 1097 - 1108
(2020/01/22)
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- Light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds
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Visible light-induced organic reactions are important chemical transformations in organic chemistry, and their efficiency highly depends on suitable photocatalysts. However, the commonly used photocatalysts are precious transition-metal complexes and elaborate organic dyes, which hamper large-scale production due to high cost. Here, for the first time, we report a novel strategy: light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds, allowing high-value-added aromatic ketones and carboxylic acids to be easily prepared in high-to-excellent yields using readily available alkyl arenes, methyl arenes and aldehydes as materials. The mechanistic investigations showed that the treatment of inexpensive and readily available sodium trifluoromethanesulfinate with oxygen under irradiation of light could in situ form a pentacoordinate sulfide intermediate as an efficient photosensitizer. The method represents a highly efficient, economical and environmentally friendly strategy, and the light and oxygen-enabled sodium trifluoromethanesulfinate photocatalytic system represents a breakthrough in photochemistry. This journal is
- Fu, Hua,Liu, Can,Liu, Yong,Yang, Haijun,Zhu, Xianjin
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supporting information
p. 4357 - 4363
(2020/07/14)
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- A Photochemical Organocatalytic Strategy for the α-Alkylation of Ketones by using Radicals
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Reported herein is a visible-light-mediated radical approach to the α-alkylation of ketones. This method exploits the ability of a nucleophilic organocatalyst to generate radicals upon SN2-based activation of alkyl halides and blue light irradiation. The resulting open-shell intermediates are then intercepted by weakly nucleophilic silyl enol ethers, which would be unable to directly attack the alkyl halides through a traditional two-electron path. The mild reaction conditions allowed functionalization of the α position of ketones with functional groups that are not compatible with classical anionic strategies. In addition, the redox-neutral nature of this process makes it compatible with a cinchona-based primary amine catalyst, which was used to develop a rare example of enantioselective organocatalytic radical α-alkylation of ketones.
- Goti, Giulio,Melchiorre, Paolo,O?eka, Maksim,Schweitzer-Chaput, Bertrand,Spinnato, Davide
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supporting information
p. 9485 - 9490
(2020/04/09)
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- Synergistic Activation of Amides and Hydrocarbons for Direct C(sp3)–H Acylation Enabled by Metallaphotoredox Catalysis
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The utilizations of omnipresent, thermodynamically stable amides and aliphatic C(sp3)?H bonds for various functionalizations are ongoing challenges in catalysis. In particular, the direct coupling between the two functional groups has not been realized. Here, we report the synergistic activation of the two challenging bonds, the amide C?N and unactivated aliphatic C(sp3)?H, via metallaphotoredox catalysis to directly acylate aliphatic C?H bonds utilizing amides as stable and readily accessible acyl surrogates. N-acylsuccinimides served as efficient acyl reagents for the streamlined synthesis of synthetically useful ketones from simple C(sp3)?H substrates. Detailed mechanistic investigations using both computational and experimental mechanistic studies were performed to construct a detailed and complete catalytic cycle. The origin of the superior reactivity of the N-acylsuccinimides over other more reactive acyl sources such as acyl chlorides was found to be an uncommon reaction pathway which commences with C?H activation prior to oxidative addition of the acyl substrate.
- Baik, Mu-Hyun,Choi, Seulhui,Hong, Soon Hyeok,Lee, Geun Seok,Won, Joonghee
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supporting information
p. 16933 - 16942
(2020/08/03)
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- Synthesis of 2,2,5-Trisubstituted 2 H-Pyrroles and 2,3,5-Trisubstituted 1 H-Pyrroles by Ligand-Controlled Site-Selective Dearomative C2-Arylation and Direct C3-Arylation
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Palladium-catalyzed site-selective dearomative C2-arylation of 2,5-diaryl-1H-pyrroles with aryl chlorides was accomplished, and a series of 2,2,5-triaryl-2H-pyrroles were synthesized. In addition, the site selectivity of the reaction was switched by simply changing the ligand, and the direct C3-arylated 2,3,5-triaryl-1H-pyrroles were prepared. The obtained 2,2,5-triaryl-2H-pyrroles could be further transformed into 2,2,5,5-tetraarylpyrrolidines.
- Yamaguchi, Miyuki,Fujiwara, Sakiko,Manabe, Kei
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supporting information
p. 6972 - 6977
(2019/09/03)
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- Proton-Coupled Electron Transfer: Transition-Metal-Free Selective Reduction of Chalcones and Alkynes Using Xanthate/Formic Acid
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Highly chemoselective reduction of α,β-unsaturated ketones to saturated ketones and stereoselective reduction of alkynes to (E)-alkenes has been developed under a transition-metal-free condition using a xanthate/formic acid mixture through proton-coupled electron transfer (PCET). Mechanistic experiments and DFT calculations support the possibility of a concerted proton electron-transfer (CPET) pathway. This Birch-type reduction demonstrates that a small nucleophilic organic molecule can be used as a single electron-transfer (SET) reducing agent with a proper proton source.
- Prasanna, Ramanathan,Guha, Somraj,Sekar, Govindasamy
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p. 2650 - 2653
(2019/04/17)
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- Catalytic Transfer Hydrogenation Using Biomass as Hydrogen Source
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We developed an operationally simple method for the direct use of biomass-derived chemical entities in a fundamentally important process, such as hydrogenation. Various carbohydrates, starch, and lignin were used for stereoselective hydrogenation. Employing a transition metal catalyst and a novel catalytic system, the reduction of alkynes, alkenes, and carbonyl groups with high yields was demonstrated. The regioselective hydrogenation to access different stereoisomers was established by simple variations in the reaction conditions. This work is based on an unprecedented catalytic system and represents a straightforward application of biomass as a reducing reagent in chemical reactions.
- Antonchick, Andrey P.,Manna, Srimanta
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p. 3094 - 3098
(2018/09/14)
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- One-Pot Synthesis of O-Heterocycles or Aryl Ketones Using an InCl3/Et3SiH System by Switching the Solvent
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An efficient one-pot synthesis of O-heterocycles or aryl ketones has been achieved using Et3SiH in the presence of InCl3 via a sequential ionic hydrogenation reaction by switching the solvent. This methodology can be used to construct C-O bonds and to prepare conjugate reduction products, including chromans, tetrahydrofurans, tetrahydropyrans, dihydroisobenzofurans, dihydrochalcones, and 1,4-diones in a facile manner. In addition, a novel plausible mechanism involving a conjugate reduction and a tandem reductive cyclization was verified by experimental investigations.
- Jia, Wenqiang,Xi, Qiumu,Liu, Tianqi,Yang, Minjian,Chen, Yonghui,Yin, Dali,Wang, Xiaojian
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p. 5141 - 5149
(2019/05/10)
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- Nonclassical Mechanism in the Cyclodehydration of Diols Catalyzed by a Bifunctional Iridium Complex
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1,4- and 1,5-diols undergo cyclodehydration upon treatment with cationic N-heterocyclic carbene (NHC)–IrIII complexes to give tetrahydrofurans and tetrahydropyrans, respectively. The mechanism was investigated, and a metal-hydride-driven pathway was proposed for all substrates, except for very electron-rich ones. This contrasts with the well-established classical pathways that involve nucleophilic substitution.
- González Miera, Greco,Bermejo López, Aitor,Martínez-Castro, Elisa,Norrby, Per-Ola,Martín-Matute, Belén
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supporting information
p. 2631 - 2636
(2019/02/01)
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- A method of synthesizing chiral alkene propyl alcohol
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The invention discloses a method for synthesizing chiral alkene propyl alcohol method, which belongs to the technical field of organic chemistry. The method adopts the [...] derived binaphthol potassium salt as a chiral [...] catalyst, catalytic [...] pro
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Paragraph 0025-0029
(2019/07/04)
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- Kinetic Resolution of Allylic Alcohol with Chiral BINOL-Based Alkoxides: A Combination of Experimental and Theoretical Studies
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The development and characterization of enantioselective catalytic kinetic resolution of allylic alcohols through asymmetric isomerization with chiral BINOL derivatives-based alkoxides as bifunctional Br?nsted base catalysts were described in the study. A number of chiral BINOL derivatives-based alkoxides were synthesized, and their structure-enantioselectivity correlation study in asymmetric isomerization identified a promising chiral Br?nsted base catalyst, which afforded various chiral secondary allylic alcohols (ee up to 99%, S factor up to >200). In the mechanistic study, alkoxide species were identified as active species and the phenol group of BINOL largely affected the high reactivity and enantioselectivity via hydrogen bonding between the chiral Br?nsted base catalyst and substrates. The strategy is the first successful synthesis strategy of various chiral secondary allylic alcohols through enantioselective transition-metal-free base-catalyzed isomerization. The applicability of the strategy had been demonstrated by the synthesis of the bioactive natural product (+)-veraguensin.
- Liu, Yidong,Liu, Song,Li, Dongmei,Zhang, Nan,Peng, Lei,Ao, Jun,Song, Choong Eui,Lan, Yu,Yan, Hailong
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p. 1150 - 1159
(2019/01/11)
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- Lead-Halide Perovskites for Photocatalytic α-Alkylation of Aldehydes
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Cost-effective and efficient photocatalysis are highly desirable in chemical synthesis. Here we demonstrate that readily prepared suspensions of APbBr3 (A = Cs or methylammonium (MA)) type perovskite colloids (ca. 2-100 nm) can selectively photocatalyze carbon-carbon bond formation reactions, i.e., α-alkylations. Specifically, we demonstrate α-alkylation of aldehydes with a turnover number (TON) of over 52,000 under visible light illumination. Hybrid organic/inorganic perovskites are revolutionizing photovoltaic research and are now impacting other research fields, but their exploration in organic synthesis is rare. Our low-cost, easy-to-process, highly efficient and bandedge-tunable perovskite photocatalyst is expected to bring new insights in chemical synthesis.
- Zhu, Xiaolin,Lin, Yixiong,Sun, Yue,Beard, Matthew C.,Yan, Yong
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supporting information
p. 733 - 738
(2019/01/23)
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- Synthesis of 1,4-Diketones via Titanium-Mediated Reductive Homocoupling of α-Haloketones
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1,4-Diketones have been synthesized via a reductive homocoupling of α-haloketones. Addition of a Grignard reagent to titanium(IV) isopropoxide affords a low-valent titanium(III) intermediate that is believed to mediate a radical dimerization reaction. The
- Le, Nathan N.,Rodriguez, Aimee M.,Alleyn, James R.,Gesinski, Michael R.
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p. 2195 - 2198
(2018/09/29)
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- Cross-coupling of dissimilar ketone enolates via enolonium species to afford non-symmetrical 1,4-diketones
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Due to their closely matched reactivity, the coupling of two dissimilar ketone enolates to form a 1,4-diketone remains a challenge in organic synthesis. We herein report that umpolung of a ketone trimethylsilyl enol ether (1 equiv) to form a discrete enol
- Parida, Keshaba N.,Pathe, Gulab K.,Maksymenko, Shimon,Szpilman, Alex M.
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p. 992 - 997
(2019/12/23)
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- Continuous Endoperoxidation of Conjugated Dienes and Subsequent Rearrangements Leading to C-H Oxidized Synthons
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We have investigated the continuous flow photooxidation of several conjugated dienes and subsequent rearrangement using a practical and safe continuous-flow homemade engineered setup. End-to-end approaches involving endoperoxidation, Kornblum-DeLaMare rearrangement, and additional rearrangements are comprehensively detailed with optimization, scope, and scale-up to obtain useful hydroxyenones, furans, and 1,4-dicarbonyl building blocks.
- De Souza, Juliana M.,Brocksom, Timothy J.,McQuade, D.Tyler,De Oliveira, Kleber T.
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p. 7574 - 7585
(2018/06/11)
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- Detrifluoroacetylation Reaction of Trifluoromethyl-β-diketones: Facile Method for the Synthesis of Succinimide Derivatives and 1,4-Diketones
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Currently, a great deal of research efforts are focused on C–C bond activation for development of novel synthetic methodology. In this paper, a detrifluoroacetylation of trifluoromethyl-β-diketones is described, which allows for the synthesis of succinimides and 1,4-diketones through cascade Michael addition/retro-Claisen reaction and nucleophilic substitution/retro-Claisen reaction. The readily available trifluoromethyl-β-diketones, wide substrate scope, and mild conditions make this method very practical.
- Wang, Li-Hua,Zhao, Jing
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p. 4345 - 4348
(2018/08/31)
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- A domino Kornblum-DeLaMare/aza-Michael reaction of 3,6-dihydro-1,2-dioxines and application to the synthesis of the ceramide transport inhibitor (±)-HPA-12
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A Kornblum-DeLaMare/aza-Michael reaction of 3,6-dihydro-1,2-dioxines with primary and secondary amines has been developed which affords 4-hydroxy-3-aminoketones. The aza-Michael products were reduced using non-selective NaBH4/MeOH or diastereoselective (up to 92:8) SnCl4/NaBH4 conditions yielding (1R?,3S?)-3-amino-1,4-diols in up to 97% and 70% yield respectively. The major reduction product was converted in two steps to (±)-HPA-12, which is an inhibitor of the cytosolic ceramide transporting protein.
- Legendre, Sarah V.A.-M.,Jevric, Martyn,Klepp, Julian,Sumby, Christopher J.,Greatrex, Ben W.
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p. 1229 - 1239
(2017/12/04)
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- Facile Synthesis of β-Keto Sulfones Employing Fenton's Reagent in DMSO
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A new facile method for the synthesis of β-keto sulfones employing xanthates, DMSO, and Fenton's reagent is described. The reaction proceeds under very mild conditions providing a cost-effective straightforward approach to various β-keto sulfones in high yields.
- Chalikidi, Petrakis N.,Uchuskin, Maxim G.,Trushkov, Igor V.,Abaev, Vladimir T.,Serdyuk, Olga V.
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supporting information
p. 571 - 575
(2018/01/11)
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- Reductive Homocoupling of Organohalides Using Nickel(II) Chloride and Samarium Metal
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A homocoupling method for organohalides and organosulfonates promoted by samarium metal and HMPA, and catalyzed by NiCl2 has been developed. Various organohalides (benzyl, aryl, heterocyclic, alkenyl and alkyl halides), α-haloacetophenones, and phenyl organosulfonates were tolerated, and the reaction afforded coupling products with high efficiency. Excellent chemoselectivity was exhibited between halides and other groups, such as ?COOH, ?NO2, halogen, heterocyclic ring, ester, and ketone groups. The stereoselectivity suggested that the reaction mechanism might involve an organosamarium species.
- Liu, Yongjun,Xiao, Shuhuan,Qi, Yan,Du, Feng
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supporting information
p. 673 - 678
(2017/03/22)
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- Enolonium Species—Umpoled Enolates
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Enolonium species/iodo(III)enolates of carbonyl compounds have been suggested to be intermediates in a wide variety of hypervalent iodine induced chemical transformations of ketones, including α-C?O, α-C?N, α-C?C, and α-carbon–halide bond formation, but they have never been characterized. We report that these elusive umpoled enolates may be made as discrete species that are stable for several minutes at ?78 °C, and report the first spectroscopic identification of such species. It is shown that enolonium species are direct intermediates in C?O, C?N, C?Cl, and C?C bond forming reactions. Our results open up chemical space for designing a variety of new transformations. We showcase the ability of enolonium species to react with prenyl, crotyl, cinnamyl, and allyl silanes with absolute regioselectivity in up to 92 % yield.
- Arava, Shlomy,Kumar, Jayprakash N.,Maksymenko, Shimon,Iron, Mark A.,Parida, Keshaba N.,Fristrup, Peter,Szpilman, Alex M.
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supporting information
p. 2599 - 2603
(2017/02/26)
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- Catalytic Activation of 1-Cyano-3,3-dimethyl-3-(1H)-1,2-benziodoxole with B(C6F5)3 Enabling the Electrophilic Cyanation of Silyl Enol Ethers
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The Lewis acidic activation of a hypervalent iodine reagent containing a transferable cyano group, 1-cyano-3,3-dimethyl-3-(1H)-1,2-benziodoxole (CDBX), with B(C6F5)3, to achieve the catalytic electrophilic cyanation of silyl enol ethers is presented. Mechanistic studies indicate that CDBX is activated through coordination of its cyano group to B(C6F5)3, thus enabling the electrophilic cyanation reaction to occur.
- Nagata, Takaya,Matsubara, Hiroki,Kiyokawa, Kensuke,Minakata, Satoshi
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supporting information
p. 4672 - 4675
(2017/09/12)
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- Synthesis and 2D-QSAR studies of neolignan-based diaryl-tetrahydrofuran and -furan analogues with remarkable activity against Trypanosoma cruzi and assessment of the trypanothione reductase activity
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Two series of diaryl-tetrahydrofuran and -furan were synthesised and screened for anti-trypanosomal activity against trypomastigote and amastigote forms of Trypanosoma cruzi, the causative agent of Chagas disease. Based on evidence that modification of a natural product may result in a more effective drug than the natural product itself, and using known neolignan inhibitors veraguensin 1 and grandisin 2 as templates to synthesise simpler analogues, remarkable anti-trypanosomal activity and selectivity were found for 3,5-dimethoxylated diaryl-furan 5c and 2,4-dimethoxylated diaryl-tetrahydrofuran 4e analogues with EC50 0.01 μM and EC50 0.75 μM, respectively, the former being 260-fold more potent than veraguensin 1 and 150-fold better than benznidazole, the current available drugs for Chagas disease treatment. The ability of the most potent anti-trypanosomal compounds to penetrate LLC-MK2 cells infected with T. cruzi amastigotes parasite was tested, which revealed 4e and 5e analogues as the most effective, causing no damage to mammalian cells. In particular, the majority of the derivatives were non-toxic against mice spleen cells. 2D-QSAR studies show the rigid central core and the position of dimethoxy-aryl substituents dramatically affect the anti-trypanosomal activity. The mode of action of the most active anti-trypanosomal derivatives was investigated by exploring the anti-oxidant functions of Trypanothione reductase (TR). As a result, diarylfuran series displayed the strongest inhibition, highlighting compounds 5d-e (IC50 19.2 and 17.7 μM) and 5f-g (IC50 8.9 and 7.4 μM), respectively, with similar or 2-fold higher than the reference inhibitor clomipramine (IC50 15.2 μM).
- Hartmann, Ana Paula,de Carvalho, Marcelo Rodrigues,Bernardes, Lilian Sibelle Campos,de Moraes, Milena Hoehr,de Melo, Eduardo Borges,Lopes, Carla Duque,Steindel, Mario,da Silva, Jo?o Santana,Carvalho, Ivone
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p. 187 - 199
(2017/09/20)
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- A novel coupling reaction of α-halo ketones promoted by SmI3/CuI
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With SmI3 as the Lewis acid and catalyzed by CuI in DMF, α-haloketones were transformed unexpectedly into α-hydroxy-1,4-diketones in good to moderate yields. The mechanism was probed and a plausible reaction pathway was proposed. DMF was assumed to play a dual role both as a hydroxyl source and as a solvent.
- Liu, Yongjun,Zhao, Hengmin,Tian, Guang,Du, Feng,Qi, Yan,Wen, Yonghong
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p. 26317 - 26322
(2016/03/25)
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- Phthalonitrile structure containing the pyrrole-based aromatic diamine and its preparation method and application (by machine translation)
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The invention discloses a pyrrole aromatic diamine containing a phthalic nitrile structure and a preparation method thereof. 2-bromoacetophenone is taken as a raw material to prepare 4-(2,5-bi(4-aminophenyl)-pyrryl) phthalonitrile by reaction of four step
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Paragraph 0050; 0051
(2017/04/14)
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- Cobalt-Catalyzed Csp3?Csp3Homocoupling
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An efficient and easy method for Csp3?Csp3homocoupling was developed using cobalt bromide as catalyst. A series of functionalized alkyl bromides and alkyl chlorides were coupled in high yields under mild conditions. This reaction seems to involve a radical intermediate. (Figure presented.).
- Cai, Yingxiao,Qian, Xin,Gosmini, Corinne
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supporting information
p. 2427 - 2430
(2016/08/16)
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- Unexpected formation of 4,4-dimethyl-1,2-disubstituted-dicarbonyl cyclopentanes from ketone enolate anions and 1,3-diiodo-2,2-dimethylpropane
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Cyclic 1,4-dicarbonyl compounds can be easily obtained by mixing a solution of aryl methyl or alkyl methyl ketone enolate anions with 1,3-diiodo-2,2-dimethylpropane in DMSO. This represents the first example of dimerization of ketone enolate anions using a simple diiodoalkane as a reagent followed by subsequent double alkylation with bis-iodide yielding a cyclopentane adduct. This methodology allows the use of a simple potassium tert-butoxide as a base at room temperature for the formation of three C-C bonds resulting in a relatively complex five-membered ring diketone structure under transition-metal-free conditions.
- Barrionuevo, Cecilia A.,Schmidt, Luciana C.,Argüello, Juan E.
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p. 4550 - 4555
(2016/06/09)
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- Synthetic method of medical intermediate 1,4-diphenyl butanedione
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The invention relates to a synthetic method of a medical intermediate 1,4-diphenyl butanedione shown in a formula (III). The synthetic method of the medical intermediate 1,4-diphenyl butanedione comprises the following steps: carrying out reaction on a compound shown in a formula (I) and a compound shown in a formula (II) in the presence of a catalyst, a nitrogen-containing ligand, an acid compound and an accelerator, and carrying out after treatment after the reaction is finished, so that the compound shown in the formula (III) is obtained, wherein X is an alkali metal element. The synthetic method provided by the invention, by selecting a specific catalyst, a ligand, an acid compound, an accelerator and a solvent, can overcome the defect that yield of the compound is too low, can obtain the target product with high yield and has a good application prospect and industrial production potential in the field of organic chemical synthesis.
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Paragraph 0050; 0051; 0052; 0053
(2017/01/17)
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- Synthesis of 1,4-Dicarbonyl Compounds from Silyl Enol Ethers and Bromocarbonyls, Catalyzed by an Organic Dye under Visible-Light Irradiation with Perfect Selectivity for the Halide Moiety over the Carbonyl Group
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We report the visible-light-induced radical coupling reaction of silyl enol ethers with α-bromocarbonyl compounds to give 1,4-dicarbonyls. The reaction was effectively accelerated using an inexpensive organic dye (eosin Y) as a photoredox catalyst. 1,4-Dicarbonyl compounds alone were afforded, without the generation of carbonyl adducts of the α-halocarbonyls, which are usually generated in the presence of fluoride anions or Lewis acids. A variety of silyl enol ethers, α-bromoketones, α-bromoesters, and α-bromoamides were applied to this system to produce the coupling compounds.
- Esumi, Naoto,Suzuki, Kensuke,Nishimoto, Yoshihiro,Yasuda, Makoto
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supporting information
p. 5704 - 5707
(2016/11/17)
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- Synthesis method of symmetric butanedione compounds
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The invention relates to a synthesis method of symmetric butanedione compounds disclosed as Formula (III). The method comprises the following steps: in a solvent, carrying out reaction on compounds disclosed as Formula (I) and compounds disclosed as Formula (II) in the presence of a catalyst, a ligand and an acidic compound; and after the reaction finishes, carrying out after-treatment, thereby obtaining the compounds disclosed as Formula (III), wherein X is an alkali metal element. Under the combined selection and synergic actions of the specific catalyst, ligand, acidic compound and solvent, the method can overcome the defect of overlow yield of butanedione compounds in the prior art, can obtain the target products at high yield, and has favorable application prospects and industrial production potential in the field of organic chemical synthesis.
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Paragraph 0119-0122
(2017/02/28)
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- Novel hybrid-pyrrole derivatives: Their synthesis, antitubercular evaluation and docking studies
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Using novel hybrid molecules for the treatment of tuberculosis is one of the latest approaches. Keeping this concept in mind, thirty two hybrid compounds were synthesized, with pyrrole as one of the moieties, clubbed to coumarin, ibuprofen and isoniazid. The compounds were evaluated against Mycobacterium tuberculosis H37Rv strain. Compounds 7e and 8e exhibited MIC of 3.7 and 5.10 μg mL-1 and growth inhibition of 95% and 92%, respectively. These compounds were also active against single drug resistant bacterial strains. The compounds were devoid of cytotoxicity when tested against Vero African green monkey kidney cell line. Docking study was carried out on enoyl acyl carrier protein enzyme to provide some understanding into the mechanism of action of these compounds.
- Saha, Rikta,Alam, Md. Mumtaz,Akhter, Mymoona
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p. 12807 - 12820
(2015/02/19)
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- Transfer hydrogenation promoted by N-heterocyclic carbene and water
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N-Heterocyclic carbenes (NHCs) promote the transfer hydrogenation of various activated C=C, C=N, and N=N bonds with water as the proton source. The NHCs act as reducing reagents to be converted into their oxides. A detailed reaction mechanism is proposed on the basis of deuterium-labeling experiments.
- Kato, Terumasa,Matsuoka, Shin-Ichi,Suzuki, Masato
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supporting information
p. 13906 - 13909
(2015/09/07)
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- Umpolung Strategy for Synthesis of β-Ketonitriles through Hypervalent Iodine-Promoted Cyanation of Silyl Enol Ethers
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An efficient method to synthesize β-ketonitriles from silyl enol ethers by an umploung hypervalent iodine(III)-CN species generated in situ from PhIO/BF3·Et2O/TMSCN has been developed for the first time. This method can be applied to structurally diverse aromatic and aliphatic substrates and further extended to preparation of bioactive compounds like 5-aminopyrazole and 5-aminoisoxazole.
- Shen, Hang,Li, Jiaqiang,Liu, Qing,Pan, Jing,Huang, Ruofeng,Xiong, Yan
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p. 7212 - 7218
(2015/07/28)
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- Successively recycle waste as catalyst: A one-pot wittig/1,4-reduction/paal-knorr sequence for modular synthesis of substituted furans
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A one-pot tandem Wittig/conjugate reduction/Paal-Knorr reaction is reported for the synthesis of di- or trisubstituted furans. This novel sequence first demonstrates the possibility of successively recycling waste from upstream steps to catalyze downstream reactions.
- Chen, Long,Du, Yi,Zeng, Xing-Ping,Shi, Tao-Da,Zhou, Feng,Zhou, Jian
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p. 1557 - 1560
(2015/03/30)
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- Breaking bonds with electrons: Stepwise and concerted reductive cleavage of C-S, C-Se and Se-CN bonds in phenacylthiocyanates and phenacylselenocyanates
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The mechanistic aspects of the electrochemical reduction of phenacylthio- and selenocyanates have been studied. With phenacylthiocyanates (1), a change in the reductive cleavage mechanism is observed as a function of the substituent on the phenyl ring. While a stepwise mechanism involving the intermediacy of a radical anion is followed for substrates bearing a strong electron withdrawing group, such as cyano and nitro substituent (1d, 1e), and a concerted mechanism is favoured for compounds bearing an electron-donating or no substituent on the phenyl ring (1a-c). A regioselective bond cleavage leads to the fragmentation of the CH2-S bond with all compounds 1a-e, further yielding the corresponding 1,4-diketone (3) as products. Contrastingly, with phenacylselenocyanates (2), two different reductive cleavages occur involving the breaking of both the CH2-Se and Se-CN bonds. Several products are obtained, all coming from nucleophilic attack at the α (phenacyl) carbon or the selenium atom.
- Bouchet, Lydia M.,Peory, Alicia B.,Robert, Marc,Argüello, Juan E.
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p. 11753 - 11760
(2015/02/19)
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- Copper/Manganese Cocatalyzed Oxidative Coupling of Vinylarenes with Ketones
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A novel copper/manganese cocatalyzed direct oxidative coupling of terminal vinylarenes with ketones via C(sp3)-H bond functionalization following C-C bond formation has been developed using tert-butyl hydroperoxide as the radical initiator. Various ketones underwent a free-radical addition of terminal vinylarenes to give the corresponding 1,4-dicarbonyl products with excellent regioselectivity and efficiency through one step. A possible reaction mechanism has been proposed.
- Lan, Xing-Wang,Wang, Nai-Xing,Zhang, Wei,Wen, Jia-Long,Bai, Cui-Bing,Xing, Yalan,Li, Yi-He
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supporting information
p. 4460 - 4463
(2015/09/28)
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- Flexible stereoselective functionalizations of ketones through umpolung with hypervalent iodine reagents
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The functionalization of carbonyl compounds in the α-position has gathered much attention as a synthetic route because of the wide biological importance of such products. Through polarity reversal, or "umpolung", we show here that typical nucleophiles, such as oxygen, nitrogen, and even carbon nucleophiles, can be used for addition reactions after tethering them to enol ethers. Our findings allow novel retrosynthetic planning and rapid assembly of structures previously accessible only by multistep sequences. A Nu approach: An efficient α-functionalization of ketones with a range of simple and useful nucleophiles is possible by using hypervalent iodine reagents (see scheme; Nu′ can be the Nu itself or a protected form of this nucleophile group).
- Mizar, Pushpak,Wirth, Thomas
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supporting information
p. 5993 - 5997
(2014/06/10)
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- Polymer-stabilized palladium nanoparticles for the chemoselective transfer hydrogenation of α,β-unsaturated carbonyls: Single-step bottom-Up approach
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Polypyrrole stabilised palladium nanoparticles show good catalytic efficiency for the chemoselective transfer hydrogenation of α,β- unsaturated carbonyl compounds. The catalyst is very specific and selectively hydrogenates the olefins or acetylenes only,
- Mahato, Sanjit K.,Ul Islam, Rafique,Acharya, Chiranjit,Witcomb, Michael J.,Mallick, Kaushik
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p. 1419 - 1426
(2014/05/20)
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