- Efficient synthesis of chiral cyclic acetals by metal and Bronsted acid co-catalyzed enantioselective four-component cascade reactions
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Four-component Mannich reactions subsequently followed by an intramolecular oxo-Michael addition were developed to efficiently produce chiral cyclic acetals with high diastereoselectivity and enantioselectivity. The Royal Society of Chemistry.
- Qiu, Lin,Guo, Xin,Ma, Chaoqun,Qiu, Huang,Liu, Shunying,Yang, Liping,Hu, Wenhao
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Read Online
- Atom-economical access to highly substituted indenes and furan-2-ones via tandem reaction of diazo compounds and propargyl alcohols
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A facile synthesis of highly substituted as well as conjugated indene/furanone systems via a BF3·OEt2 catalyzed tandem reaction of α-diazo-esters/-amides and propargyl alcohols has been demonstrated under mild conditions. This method
- Muthusamy, Sengodagounder,Sivaguru, Manickasamy
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Read Online
- Palladium-Catalyzed Migratory Insertion of Carbenes and C-C Cleavage of Cycloalkanecarboxamides
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A palladium catalyzed reaction of cycloalkanecarboxamides and diazomalonates or bis(phenylsulfonyl)diazomethane has been developed. The reaction proceeds via carbene migratory insertion and cascade C-C cleavage pathways. Cycloalkanecarboxamides with four to seven membered rings are applicable in the transformation. A series of ring opening products were prepared with moderate yields. The finding provides valuable clues for the development of new reactions involving carbene migratory insertion and the cleavage of unstrained C(sp3)-C(sp3) bonds.
- Zhang, Peng,Zeng, Jia,Pan, Ping,Zhang, Xue-Jing,Yan, Ming
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supporting information
p. 536 - 541
(2022/01/20)
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- Synthesis of Functionalized Silsesquioxane Nanomaterials by Rhodium-Catalyzed Carbene Insertion into Si?H Bonds
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We report carbene insertion into Si?H bonds of polyhedral oligomeric silsesquioxanes (POSS) for the synthesis of highly functionalized siloxane nanomaterials. Dirhodium(II) carboxylates catalyze insertion of aryl-diazoacetates as carbene precursors to afford POSS structures containing both ester and aryl groups as orthogonal functional handles for further derivatization of POSS materials. Four diverse and structurally varied silsesquioxane core scaffolds with one, three, or eight Si?H bonds were evaluated with diazo reactants to produce a total of 20 new POSS compounds. Novel diazo compounds containing a fluorinated octyl group and boron-dipyrromethene (BODIPY) chromophore demonstrate the use of highly functionalized substrates. Transformations of aryl(ester)-functionalized POSS compounds derived from this method are demonstrated, including ester hydrolysis and Suzuki–Miyaura cross-coupling.
- Franz, Annaliese K.,Jagannathan, Jake R.,Targos, Karina
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supporting information
(2021/11/27)
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- Blue LED Induced Manganese (I) Catalysed Direct C2?H Activation of Pyrroles with Aryl Diazoesters
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Herein, we have reported a blue LED mediated manganese pentacarbonyl bromide catalysed incorporation of carbene moieties from aryl diazoesters onto 1H-pyrroles via their selective C2?H activation. A manganese metal-carbene has been identified as the active catalyst to facilitate the reaction. Eighteen mono substituted pyrrole derivatives were isolated in good to excellent yields (67→82%) and the disubstituted products were also formed in minor quantities (5 to 8%). HPLC based kinetics study enabled optimization of the reaction. Control experiments, FT-IR, NMR and GC-MS based characterization elucidated the putative reaction mechanism. (Figure presented.).
- Sar, Saibal,Das, Ranajit,Sen, Subhabrata
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p. 3521 - 3531
(2021/06/09)
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- Catalyst-free, scalable heterocyclic flow photocyclopropanation
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Industrial process development is driven by several factors, including safety, cost, robustness and environmental aspects. However, attempts to establish aryl diazo esters-which are highly valued in academic research for their reactivity as carbene precur
- Kl?pfer, Viktor,Eckl, Robert,Flo?, Johannes,Roth, Philippe M. C.,Reiser, Oliver,Barham, Joshua P.
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supporting information
p. 6366 - 6372
(2021/09/10)
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- Copper-Catalyzed 1,1-Alkylmonofluoroalkylation of Terminal Alkynes with Diazo Compounds and 2-Fluoro-1,3-dicarbonyl Compounds: Access toward (E)-β-Monofluoroalkyl-β,γ-unsaturated Esters or Ketones
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An efficient copper-catalyzed three-component 1,1-alkylmonofluoroalkylation of terminal alkynes, diazo compounds, and 2-fluoro-1,3-dicarbonyl compounds for the synthesis of (E)-β-monofluoroalkyl-β,γ-unsaturated esters or ketones has been developed. The methodology features a broad substrate scope, an inexpensive and easily available catalytic system, and excellent selectivity with good yields. The mechanism of the tandem Cu-catalyzed cross-coupling and nucleophilic addition of allenes has been investigated.
- Chen, Chen,Lv, Yunhe,Pu, Weiya,Wang, Shanshan,Zhu, Xueli
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p. 10043 - 10054
(2021/08/20)
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- Borane catalysed cyclopropenation of arylacetylenes
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Triarylboranes have gained substantial attention as catalysts for C-C bond forming reactions due to their remarkable catalytic activities. Herein, we report B(C6F5)3catalysed cyclopropenation of a wide variety of arylacetylenes using donor-acceptor diazoesters. A mild reaction protocol has been developed for the synthesis of functionalised cyclopropenes (33 examples) in good to excellent yields.
- Dasgupta, Ayan,Heard, Matthew J.,Melen, Rebecca L.,Stefkova, Katarina
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supporting information
p. 6736 - 6739
(2021/07/13)
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- Borane Catalyzed Selective Diazo Cross-Coupling Towards Pyrazoles
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Decomposition of donor-acceptor diazo compounds leads to the formation of reactive carbene intermediates. These can undergo a wide variety of carbene transfer reactions to yield synthetically useful products. Herein, we report a selective borane catalyzed cyclization reaction from the combination of two different diazo compounds to afford N-substituted pyrazoles. The selective decomposition of the more reactive α-aryl α-diazoester and subsequent reaction with a vinyl diazoacetate produces N-alkylated pyrazoles in a regioselective manner. Catalytic amounts of tris(pentafluorophenyl)borane (10 mol%) were employed to afford the pyrazole products (36 examples) in yields from 59 to 80%. Extensive DFT studies have been undertaken to interpret the mechanism for this reaction which was found to go through two tandem catalytic cycles, both catalyzed by B(C6F5)3.
- Ariafard, Alireza,Babaahmadi, Rasool,Dasgupta, Ayan,Gierlichs, Lukas,Melen, Rebecca L.,Pahar, Sanjukta,Yates, Brian F.
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- α-Xanthylmethyl Ketones from α-Diazo ketones
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A simple and efficient method to obtain α-xanthylmethyl ketones from α-diazo ketones is described. The reaction proceeds through a protonation/nucleophilic substitution sequence in the presence of p -toluenesulfonic acid and potassium ethyl xanthogenate as the nucleophile. As α-diazo ketones can be readily synthesized from ubiquitous carboxylic acids, a broad variety of xanthates can be obtained, including examples from naturally occurring substrates.
- López-Mendoza, Pedro,Miranda, Luis D.
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p. 3777 - 3790
(2021/07/07)
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- Azide Radical Initiated Ring Opening of Cyclopropenes Leading to Alkenyl Nitriles and Polycyclic Aromatic Compounds
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We report herein a radical-mediated amination of cyclopropenes. The transformation proceeds through a cleavage of the three-membered ring after the addition of an azide radical on the strained double bond and leads to tetrasubstituted alkenyl nitrile derivatives upon loss of N2. With 1,2-diaryl substituted cyclopropenes, this methodology could be extended to a one-pot synthesis of highly functionalized polycyclic aromatic compounds (PACs). This transformation allows the synthesis of nitrile-substituted alkenes and aromatic compounds from rapidly accessed cyclopropenes using only commercially available reagents.
- Muriel, Bastian,Waser, Jerome
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supporting information
p. 4075 - 4079
(2021/01/18)
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- Synthesis of Quinolines via the Metal-free Visible-Light-Mediated Radical Azidation of Cyclopropenes
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We report the synthesis of quinolines using cyclopropenes and an azidobenziodazolone (ABZ) hypervalent iodine reagent as an azide radical source under visible-light irradiation. Multisubstituted quinoline products were obtained in 34-81% yield. The reaction was most efficient for 3-trifluoromethylcyclopropenes, affording valuable 4-trifluoromethylquinolines. The transformation probably proceeds through the cyclization of an iminyl radical formed by the addition of the azide radical on the cyclopropene double bond, followed by ring-opening and fragmentation.
- Smyrnov, Vladyslav,Muriel, Bastian,Waser, Jerome
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supporting information
p. 5435 - 5439
(2021/07/21)
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- Engineering Dirhodium Artificial Metalloenzymes for Diazo Coupling Cascade Reactions**
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Artificial metalloenzymes (ArMs) are commonly used to control the stereoselectivity of catalytic reactions, but controlling chemoselectivity remains challenging. In this study, we engineer a dirhodium ArM to catalyze diazo cross-coupling to form an alkene that, in a one-pot cascade reaction, is reduced to an alkane with high enantioselectivity (typically >99 % ee) by an alkene reductase. The numerous protein and small molecule components required for the cascade reaction had minimal effect on ArM catalysis. Directed evolution of the ArM led to improved yields and E/Z selectivities for a variety of substrates, which translated to cascade reaction yields. MD simulations of ArM variants were used to understand the structural role of the cofactor on ArM conformational dynamics. These results highlight the ability of ArMs to control both catalyst stereoselectivity and chemoselectivity to enable reactions in complex media that would otherwise lead to undesired side reactions.
- Bultman, Max J.,Huang, Rui,Lewis, Jared C.,Li, Ying,Roux, Benoit,Upp, David M.
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supporting information
p. 23672 - 23677
(2021/08/23)
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- Generation of Tosyl Azide in Continuous Flow Using an Azide Resin, and Telescoping with Diazo Transfer and Rhodium Acetate-Catalyzed O–H Insertion
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Generation of tosyl azide 12 in acetonitrile in flow under water-free conditions using an azide resin and its use in diazo transfer to a series of aryl acetates are described. Successful telescoping with a rhodium acetate-catalyzed O–H insertion has been
- Collins, Stuart G.,Lynch, Denis,Maguire, Anita R.,O'callaghan, Katie S.,O'mahony, Rosella M.
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p. 2772 - 2785
(2021/12/13)
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- Tropylium-Catalyzed O-H Insertion Reactions of Diazoalkanes with Carboxylic Acids
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Herein, we describe the application of a nonbenzenoid aromatic carbocation, namely tropylium, as an organic Lewis acid catalyst in O-H functionalization reactions of diazoalkanes with benzoic acids. The newly developed protocol is applicable to a wide range of diazoalkane and carboxylic acid substrates with excellent efficiency (43 examples, up to 99% yield).
- Empel, Claire,Nguyen, Thanh Vinh,Koenigs, Rene M.
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supporting information
p. 548 - 553
(2021/01/26)
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- Dirhodium(II)/Xantphos-Catalyzed Relay Carbene Insertion and Allylic Alkylation Process: Reaction Development and Mechanistic Insights
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Although dirhodium-catalyzed multicomponent reactions of diazo compounds, nucleophiles and electrophiles have achieved great advance in organic synthesis, the introduction of allylic moiety as the third component via allylic metal intermediate remains a formidable challenge in this area. Herein, an attractive three-component reaction of readily accessible amines, diazo compounds, and allylic compounds enabled by a novel dirhodium(II)/Xantphos catalysis is disclosed, affording various architecturally complex and functionally diverse α-quaternary α-amino acid derivatives in good yields with high atom and step economy. Mechanistic studies indicate that the transformation is achieved through a relay dirhodium(II)-catalyzed carbene insertion and allylic alkylation process, in which the catalytic properties of dirhodium are effectively modified by the coordination with Xantphos, leading to good activity in the catalytic allylic alkylation process.
- Liang, Xinyi,Lu, Bin,Peng, Qian,Wang, Xiaoming,Wang, Zijian,Zhang, Jinyu
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supporting information
p. 11799 - 11810
(2021/08/16)
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- Visible-light-promoted selective: O -alkylation of 2-pyridones with α-aryldiazoacetates
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A visible-light-promoted O-H insertion reaction between 2-pyridones and α-aryldiazoacetates has been developed. Upon visible light irradiation, the reaction proceeds smoothly under mild and catalyst-free conditions. A wide scope of 2-pyridones and α-aryldiazoacetates are well tolerated, and various O-alkylated 2-pyridones are obtained with perfect selectivity and good functional group tolerance. A photoinduced radical process is probably responsible for the excellent selectivity. This journal is
- Yang, Jingya,Wang, Ganggang,Zhou, Hongyan,Li, Zhifeng,Ma, Ben,Song, Menghui,Sun, Rongxia,Huo, Congde
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supporting information
p. 394 - 398
(2021/01/29)
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- Divergent Synthesis of Aziridine and Imidazolidine Frameworks under Blue LED Irradiation
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We develop a visible light-promoted divergent cycloaddition of α-diazo esters with hexahydro-1,3,5-triazines, leading to a series of aziridine and imidazolidine frameworks in average good yield, by simply changing the reaction media used. It is noteworthy that the reaction occurs under sole visible light irradiation without the need for exogenous photoredox catalysts. More significantly, a reasonable reaction mechanism was proposed on the basis of the control experiments and density functional theory calculation results.
- Cheng, Xiao,Cai, Bao-Gui,Mao, Hui,Lu, Juan,Li, Lei,Wang, Kun,Xuan, Jun
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supporting information
p. 4109 - 4114
(2021/05/26)
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- Oxime Ether Synthesis through O-H Functionalization of Oximes with Diazo Esters under Blue LED Irradiation
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A green and sustainable oxime ether formation method via the visible-light-promoted O-H functionalization of oximes with diazo esters is described. The reaction occurs under very mild conditions (catalyst- and additive-free) with a high yield and a high functional group tolerance. When the reaction was performed with a cyclic ether as the solvent (e.g., THF, 1,4-dioxane, tetrahydropyran, ect.), an interesting photochemical three-component reaction product was obtained in good yields.
- Li, Qian,Cai, Bao-Gui,Li, Lei,Xuan, Jun
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supporting information
p. 6951 - 6955
(2021/09/02)
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- Visible-Light-Promoted Polysubstituted Olefins Synthesis Involving Sulfur Ylides as Carbene Trapping Reagents
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A blue-light-emitting diode (LED) promoted coupling of aryl diazoacetates with sulfur ylides is described. This protocol features mild conditions, good functional group tolerance, and broad substrate scope for both aryl diazoacetates with sulfur ylides. Under optimal reaction conditions, a wide range of trisubstituted olefins is obtained in moderate to good yield, which can be further transferred to other biologically important heterocycles after a two-step simple operation.
- Ye, Cong,Cai, Bao-Gui,Lu, Juan,Cheng, Xiao,Li, Lei,Pan, Zhong-Wen,Xuan, Jun
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p. 1012 - 1022
(2021/01/09)
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- Blue LED-Mediated N-H Insertion of Indoles into Aryldiazoesters at Room Temperature in Batch and Flow: Reaction Kinetics, Density Functional Theory, and Mechanistic Study
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Mild blue light-mediated N-H insertion of indole and its derivatives into aryldiazoesters has been reported in a batch and flow strategy to afford the corresponding N-alkylated product in moderate-to-excellent yield. Detailed high-performance liquid chromatography-based reaction kinetics measurements, control experiments, and kinetic isotope effect reveal that 3-substituted indoles with electron-withdrawing groups such as -CN and -CHO facilitated the product formation, whereas the electron-donating group retarded the process. The neutral indole performed in between them. Furthermore, Hammett plot and density functional theory-based transition-state optimization studies showed substantial correlation of the electronic nature of the substituents at the C3 position of indoles with the rate of the N-H insertion reaction. The strategy was utilized to synthesize a key intermediate for the natural product (-)-psychotrimine.
- Maiti, Debajit,Das, Ranajit,Sen, Subhabrata
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p. 2522 - 2533
(2021/02/05)
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- Blue Light-Emitting Diode-Mediated in Situ Generation of Pyridinium and Isoquinolinium Ylides from Aryl Diazoesters: Their Application in the Synthesis of Diverse Dihydroindolizine
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Blue light-emitting diode-mediated environmentally sustainable three component reactions among pyridine/isoquinoline 1/2, aryl diazoesters 3, and acrylic ester/3-alkenyl oxindoles 5/6 provide various dihydroindolizines 7 to 9 in excellent yield. The principle of the strategy is photolytic generation of nitrogen ylides from N-heteroarenes and aryl diazoesters and their subsequent [3 + 2] cycloaddition reaction with dipolarophiles. Detailed mechanistic analysis of the transformation through control experiments establishes this strategy as the foundation for the photolytic multicomponent reaction.
- Guha, Souvik,Maiti, Debajit,Prabakar, Tejas,Sar, Saibal,Sen, Subhabrata
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p. 11736 - 11747
(2021/09/02)
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- Selective Alkynylallylation of the C?C σ Bond of Cyclopropenes
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A Pd-catalyzed regio- and stereoselective alkynylallylation of a specific C?C σ bond in cyclopropenes, using allyl propiolates as both allylation and alkynylation reagents, has been achieved for the first time. By merging selective C(sp2)-C(sp3) bond scission with conjunctive cross-couplings, this decarboxylative reorganization reaction features fascinating atom and step economy and provides an efficient approach to highly functionalized dienynes from readily available substrates. Without further optimization, gram-scale products can be easily obtained by such a simple, neutral, and low-cost catalytic system with high TONs. DFT calculations afford a rationale toward the formation of the products and indicate that the selective insertion of the double bond of cyclopropenes into the C-Pd bond of ambidentate Pd complex and the subsequent nonclassical β-C elimination promoted by 1,4-palladium migration are critical for the success of the reaction.
- Chen, Ying-Chun,Jiang, Zeqi,Niu, Sheng-Li,Ouyang, Qin,Xiao, Qing,Zeng, Qiang
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supporting information
p. 297 - 303
(2020/11/30)
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- Copper-Catalyzed Regioselective Coupling of Tosylhydrazones and 2-Pyridones: A Strategy for the Production of N-Alkylated Compounds
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The highly regioselective N-alkylation reaction of 2-pyridones was achieved through hydrazone chemistry, especially for substrates with bulky secondary alkyl groups. Described herein is a copper-catalyzed coupling reaction of pyridone derivatives with tosylhydrazones.
- Wu, Ye-Bin,Wu, You-Zhi,Wu, Jian,Xu, Dan,Jiang, Hui,Chang, Wen-Wu,Ma, Chang-You
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p. 6918 - 6926
(2021/05/06)
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- Visible Light-Promoted Sulfoxonium Ylides Synthesis from Aryl Diazoacetates and Sulfoxides
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A visible light-promoted reaction of donor/acceptor diazoalkanes with sulfoxides towards the synthesis of synthetically useful sulfoxonium ylides was reported. The reaction occurred under sole visible light irradiation without the need of any transition-metals or additives, affording the corresponding sulfoxonium ylides in moderate to good yields. The success of late-stage modification of natural isolates or drug candidates, scale-up reaction and transformation of sulfoxonium ylides to other useful molecules further rendered the approach valuable.
- Lu, Juan,Li, Lei,He, Xiang-Kui,Xu, Guo-Yong,Xuan, Jun
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supporting information
p. 1646 - 1650
(2021/05/28)
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- B(C6F5)3-catalyzed O-H insertion reactions of diazoalkanes with phosphinic acids
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A highly efficient base-, metal-, and oxidant-free catalytic O-H insertion reaction of diazoalkanes and phosphinic acids in the presence of B(C6F5)3has been developed. This powerful methodology provides a green approach towards the synthesis of a broad spectrum of α-phosphoryloxy carbonyl compounds with good to excellent yields (up to 99% yield). The protocol features the advantages of operational simplicity, high atom economy, practicality, easy scalability and environmental friendliness.
- Jiang, Jun,Zhang, Xinzhi,Zhang, Yangyang,Zhao, Jincheng
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p. 5772 - 5776
(2021/07/12)
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- Indolocyclobutane skeleton compound, and synthesis method and application thereof
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The invention discloses an indolocyclobutane skeleton compound as well as a synthesis method and application thereof. The indolocyclobutane skeleton compound comprises a compound with a structure as shown in a formula I or a formula II which is described
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- 2-azabicyclo [3.2.0] compound as well as synthesis method and application
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The invention discloses a 2-azabicyclo [3.2.0] compound as well as a synthesis method and an application. The 2-azabicyclo [3.2.0] compound comprises a compound with a structure as shown in a formula I and pharmaceutically acceptable salts thereof, wherein R is a substituted or unsubstituted benzene ring, a C1-8 aliphatic group or trifluoromethyl, R1 and R2 are respectively a substituted or unsubstituted benzene ring, a hydrogen atom or a C1-8 aliphatic group, R3 is a substituted or unsubstituted benzene ring, a hydrogen atom, a C1-8 aliphatic group or a heterocyclic substituent, R4 is a heterocyclic substituent or a substituted or unsubstituted benzene ring, R5 is a C1-8 fatty group, a benzyl group or -COOR6, and R6 is a C1-4 fatty group or a benzyl group. The invention belongs to the technical field of pharmaceutical chemicals, and after the prepared 2-azabicyclo [3.2.0] compound acts on an animal body, anti-sedation and anti-hypnosis effects can be achieved by adjusting the intracerebral level of histamine.
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- B(C6F5)3-Catalyzed site-selective N1-alkylation of benzotriazoles with diazoalkanes
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Alkylation of benzotriazoles is synthetically challenging, often leading to mixtures of N1 and N2 alkylation. Herein, metal-free catalytic site-selective N1-alkylation of benzotriazoles with diazoalkanes is described in the presence of 10 mol% of B(C6F5)3. These reactions provide N1-alkylated benzotriazoles in good to excellent yields and this protocol is successfully adapted to gram-scale syntheses as well as a derivative with antimicrobial activity.
- Guo, Jing,Mandal, Dipendu,Stephan, Douglas W.,Wu, Yile,Zhao, Yunbo
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p. 7758 - 7761
(2021/08/13)
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- Copper-catalyzed carbene insertion and ester migration for the synthesis of polysubstituted pyrroles
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Copper-catalyzed carbene insertion/ester migration/cyclization of enaminones and α-diazo compounds occurred efficiently to afford 2-ester polysubstituted pyrroles under mild conditions in moderate-to-good yields. Substituent functionality was well tolerated and13C-labelled experiments demonstrated 1,2-ester migration during the reaction.
- Li, Mingrui,Sun, Yiming,Xie, Yuxing,Yu, Yang,Huang, Fei,Huang, He
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supporting information
p. 11050 - 11053
(2020/10/05)
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- Borane-Catalyzed Stereoselective C–H Insertion, Cyclopropanation, and Ring-Opening Reactions
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Lewis acidic boranes have been shown to be effective metal-free catalysts for highly selective reactions of donor-acceptor diazo compounds to a range of substrates. The reactions of α-aryl α-diazoesters with nitrogen heterocycles indole or pyrrole selectively generate C3 and C2 C–H insertion products, respectively, in good to excellent yields even when using unprotected indoles. Alternatively, benzofuran, indene, and alkene substrates give exclusively cyclopropanated products with α-aryl α-diazoesters, whereas the reactions with furans lead to ring-opening. Comprehensive theoretical calculations have been used to explain the differing reactivities and high selectivities of these reactions. Overall, this work demonstrates the selective metal-free catalytic reactions of α-aryl α-diazoesters with (hetero)cycles and alkenes. This simple, mild reaction protocol represents an alternative to the commonly used precious metal systems and may provide future applications in the generation of biologically active compounds. Efficient and facile routes to heterocyclic compounds are highly desirable because of their remarkable biological importance and applications in drugs approved by the Food and Drug Administration. Current synthetic routes frequently use precious metal-catalyzed reactions. The problems associated with the limited resources of precious metals as well as their toxicities can be avoided through metal-free approaches. Our investigations on the reactivities of diazoesters toward the (hetero)arenes reveal that by using Lewis acidic triarylboranes as a catalyst, we can selectively effect C–H insertion, cyclopropanation, or ring-opening in good to excellent yields. Main group, or metal-free, catalysis has become a burgeoning field; yet, this flourishing field is still in its nascent stage. The work described herein represents a step toward improving the applicability of main group catalysis by employing metal-free approaches in the functionalization of organic compounds. This work demonstrates the highly selective metal-free catalytic reactions of α-aryl α-diazoesters with a range of (hetero)cycles and olefins using Lewis acidic boranes. The simple, mild reaction protocol employed represents an alternative to the commonly used precious metal systems and may provide future applications in the generation of biologically active compounds.
- Dasgupta, Ayan,Babaahmadi, Rasool,Slater, Ben,Yates, Brian F.,Ariafard, Alireza,Melen, Rebecca L.
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supporting information
p. 2364 - 2381
(2020/08/14)
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- Tridentate Nickel(II)-Catalyzed Chemodivergent C-H Functionalization and Cyclopropanation: Regioselective and Diastereoselective Access to Substituted Aromatic Heterocycles
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A Schiff-base nickel(II)-phosphene-catalyzed chemodivergent C-H functionalization and cyclopropanation of aromatic heterocycles is reported in moderate to excellent yields and very good regioselectivity and diastereoselectivity. The weak, noncovalent interaction between the phosphene ligand and Ni center facilitates the ligand dissociation, generating the electronically and coordinatively unsaturated active catalyst. The proposed mechanisms for the reported reactions are in good accord with the experimental results and theoretical calculations, providing a suitable model of stereocontrol for the cyclopropanation reaction.
- Nag, Ekta,Gorantla, Sai Manoj N. V. T.,Arumugam, Selvakumar,Kulkarni, Aditya,Mondal, Kartik Chandra,Roy, Sudipta
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supporting information
p. 6313 - 6318
(2020/09/02)
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- Diastereoselective Trapping of Transient Carboxylic Oxonium Ylides with α,β-Unsaturated 2-Acyl Imidazoles
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By developing a diastereoselective reaction of cyclopropene carboxylic acids with α,β-unsaturated 2-acyl imidazoles, we reported here a Michael-type trapping of transient carboxylic oxonium ylides. This transformation provides a direct approach for the construction of valuable γ-butenolide derivatives in good yields (60–99%) with high diastereoselectivities (up to >95:5 dr) under mild reaction conditions. (Figure presented.).
- Zhang, Mengchu,Zhang, Tianyuan,Zhang, Dan,Hu, Wenhao
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supporting information
p. 4662 - 4667
(2020/09/23)
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- Semi-Synthesis of C-Ring Cyclopropyl Analogues of Fraxinellone and Their Insecticidal Activity against Mythimna separata Walker
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Fraxinellone (1) is a naturally occurring degraded limonoid isolated from Meliaceae and Rutaceae plants. As a potential natural-product-based insecticidal agent, fraxinellone has been structurally modified to improve its activity. Furan ring of fraxinellone is critical in exhibiting its insecticidal activity, but with few modifications. Herein, C-ring-modified cyclopropyl analogues were semi-synthesized by Rh(II)-catalyzed cyclopropanation. The structures of the target compounds were well characterized by NMR and HRMS. The precise three-dimensional structural information of 3a was established by X-ray crystallography. Their insecticidal activity was evaluated against Mythimna separata Walker by a leaf-dipping method. Compound 3c exhibited stronger insecticidal activity than 1 and toosendanin against M. separata with teratogenic symptoms during the different periods, implying that cyclopropanation of the furan ring could strengthen the insecticidal activity of fraxinellone.
- Dong, Qing-Miao,Tang, Jiang-Jiang,Wang, Min-Ran,Yang, Xiao-Jun
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- Thermal Stability and Explosive Hazard Assessment of Diazo Compounds and Diazo Transfer Reagents
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Despite their wide use in academia as metal-carbene precursors, diazo compounds are often avoided in industry owing to concerns over their instability, exothermic decomposition, and potential explosive behavior. The stability of sulfonyl azides and other diazo transfer reagents is relatively well understood, but there is little reliable data available for diazo compounds. This work first collates available sensitivity and thermal analysis data for diazo transfer reagents and diazo compounds to act as an accessible reference resource. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and accelerating rate calorimetry (ARC) data for the model donor/acceptor diazo compound ethyl (phenyl)diazoacetate are presented. We also present a rigorous DSC dataset with 43 other diazo compounds, enabling direct comparison to other energetic materials to provide a clear reference work to the academic and industrial chemistry communities. Interestingly, there is a wide range of onset temperatures (Tonset) for this series of compounds, which varied between 75 and 160 °C. The thermal stability variation depends on the electronic effect of substituents and the amount of charge delocalization. A statistical model is demonstrated to predict the thermal stability of differently substituted phenyl diazoacetates. A maximum recommended process temperature (TD24) to avoid decomposition is estimated for selected diazo compounds. The average enthalpy of decomposition (?"HD) for diazo compounds without other energetic functional groups is-102 kJ mol-1. Several diazo transfer reagents are analyzed using the same DSC protocol and found to have higher thermal stability, which is in general agreement with the reported values. For sulfonyl azide reagents, an average ?"HD of-201 kJ mol-1 is observed. High-quality thermal data from ARC experiments shows the initiation of decomposition for ethyl (phenyl)diazoacetate to be 60 °C, compared to that of 100 °C for the common diazo transfer reagent p-acetamidobenzenesulfonyl azide (p-ABSA). The Yoshida correlation is applied to DSC data for each diazo compound to provide an indication of both their impact sensitivity (IS) and explosivity. As a neat substance, none of the diazo compounds tested are predicted to be explosive, but many (particularly donor/acceptor diazo compounds) are predicted to be impact-sensitive. It is therefore recommended that manipulation, agitation, and other processing of neat diazo compounds are conducted with due care to avoid impacts, particularly in large quantities. The full dataset is presented to inform chemists of the nature and magnitude of hazards when using diazo compounds and diazo transfer reagents. Given the demonstrated potential for rapid heat generation and gas evolution, adequate temperature control and cautious addition of reagents that begin a reaction are strongly recommended when conducting reactions with diazo compounds.
- Green, Sebastian P.,Wheelhouse, Katherine M.,Payne, Andrew D.,Hallett, Jason P.,Miller, Philip W.,Bull, James A.
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supporting information
p. 67 - 84
(2020/01/31)
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- Blue Light-Promoted N?H Insertion of Carbazoles, Pyrazoles and 1,2,3-Triazoles into Aryldiazoacetates
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Blue light irradiation of aryldiazoacetates leads to the formation of free carbenes, which can react with carbazoles, pyrazoles and 1,2,3-triazoles to afford the corresponding N?H inserted products. These reactions are performed under air and at room temperature, allowing the mild preparation of a variety of motifs found in biologically relevant targets. (Figure presented.).
- Stivanin, Mateus L.,Fernandes, Alessandra A. G.,da Silva, Amanda F.,Okada, Celso Y.,Jurberg, Igor D.
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supporting information
p. 1106 - 1111
(2020/01/25)
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- Room Temperature Coupling of Aryldiazoacetates with Boronic Acids Enhanced by Blue Light Irradiation
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A visible-light-promoted photochemical protocol is reported for the coupling of aryldiazoacetates with boronic acids. This photochemical reaction shows great enhancement compared to the same protocol performed in the absence of light. Except for a few cases, the room temperature coupling in the dark (thermal process) generally does not work. When it does, it is likely to also involve free carbenes as key intermediates. Alternatively, photochemical reactions show a broad scope, can be performed under air and tolerate a wide variety of functional groups. Reaction-evolution monitoring, DFT calculations and control experiments have been used to evaluate the main aspects of this intricate mechanistic scenario. Biologically active molecules Adiphenine, Benactyzine and Aprophen have been prepared as examples of synthetic applications.
- da Silva, Amanda F.,Afonso, Marco A. S.,Cormanich, Rodrigo A.,Jurberg, Igor D.
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supporting information
p. 5648 - 5653
(2020/04/22)
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- Photochemical Doyle-Kirmse Reaction: A Route to Allenes
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This Letter describes the metal-free, blue-light-induced [2,3]-sigmatropic rearrangement of sulfonium ylides generated from donor/acceptor diazoalkanes and propargyl sulfides. The reaction furnishes highly functionalized allenes from a broad range of starting materials in decent yield. Mechanistic experiments supported by the literature data suggest singlet carbenes as intermediates in this reaction.
- Or?owska, Katarzyna,Rybicka-Jasińska, Katarzyna,Krajewski, Piotr,Gryko, Dorota
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supporting information
p. 1018 - 1021
(2020/01/31)
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- Multi-substituted pyrrole derivative and preparation method thereof
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The invention discloses a multi-substituted pyrrole derivative and a preparation method thereof, and relates to the field of organic synthesis. According to the preparation method, diazonium or phenylhydrazone reacts with amino substituted unsaturated car
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Paragraph 0031-0032
(2020/02/27)
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- Catalytic O-H bond insertion reactions using surface modified sewage sludge as a catalyst
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Developing a greener, sustainable catalyst is a very important but challenging task in organic synthesis. Herein, for the first time, we choose more economical and greener surface modified sewage sludge-derived carbonaceous materials (SW) treated by perch
- Baell, Jonathan B.,He, Yide,Huang, Fei,Huang, He,Xu, Yao,Yi, Xiangyan,Yu, Yang,Zhang, Zhipeng
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supporting information
p. 1594 - 1604
(2020/03/26)
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- Diazo Activation with Diazonium Salts: Synthesis of Indazole and 1,2,4-Triazole
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A donor/acceptor diazo activation strategy, processing via condensation using diazonium salts without the addition of any other catalysts or reagents, is reported. The diazenium intermediate was found to undergo cyclization to give indazoles in excellent yields. Alternatively, in the presence of nitriles, substituted 1,2,4-triazoles were obtained in good to excellent yields. This interesting diazenium route provides a new approach to achieve complex heterocycle synthesis under mild conditions.
- Li, Xuming,Ye, Xiaohan,Wei, Chiyu,Shan, Chuan,Wojtas, Lukasz,Wang, Qilin,Shi, Xiaodong
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supporting information
p. 4151 - 4155
(2020/06/05)
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- Pd-Catalyzed Decarboxylative Olefination: Stereoselective Synthesis of Polysubstituted Butadienes and Macrocyclic P-glycoprotein Inhibitors
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The efficient and stereoselective synthesis of polysubstituted butadienes, especially the multifunctional butadienes, represents a great challenge in organic synthesis. Herein, we wish to report a distinctive Pd(0) carbene-initiated decarboxylative olefination approach that enables the direct coupling of diazo esters with vinylethylene carbonates (VECs), vinyl oxazolidinones, or vinyl benzoxazinones to afford alcohol-, amine-, or aniline-containing 1,3-dienes in moderate to high yields and with excellent stereoselectivity. This protocol features operational simplicity, mild reaction conditions, a broad substrate scope, and gram-scalability. Notably, a structurally unique allylic Pd(II) intermediate was isolated and characterized. DFT calculation and control experiments demonstrated that a rare Pd(0) carbene intermediate could be involved in this reaction. Moreover, the polysubstituted butadienes as novel building blocks were unprecedentedly assembled into macrocycles, which efficiently inhibited the P-glycoprotein and dramatically reversed multidrug resistance in cancer cells by 190-fold.
- Chen, Xiangyang,Hao, Jiping,Houk, K. N.,Li, Yingzi,Lou, Liguang,Quan, Haitian,Song, Bichao,Wang, Lu,Xia, Yuanzhi,Xie, Peipei,Xu, Zhongliang,Yang, Weibo
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supporting information
p. 9982 - 9992
(2020/06/27)
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- Catalytic C-C coupling of diazo compounds with arylboronic acids: Using surface modified sewage sludge as catalyst
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A green, mild and efficient synthesis of diarylmethines using sewage sludge-derived carbonaceous materials (SW) by perchloric acid catalyzed coupling reactions between diazo compounds and arylboronic acids was developed. The reaction shows a high level of functional tolerance and a broad substrate scope. Furthermore, the highly selective 1,2-alkyl shift products were furnished through the sterically demanding R4, R5 migration of diazo compounds (3-diazochromanone). The structures of 1,2-shift products have been further confirmed by single-crystal X-ray analysis. Significantly, the synthesis of the core structures of darifenacin (a clinical drug for overactive bladder syndrome, OAB) and diclofensine (a stimulant drug showing antidepressant and monoamine reuptake inhibitor activity) further demonstrated the efficacy and synthetic potential of this method. This journal is
- Huang, Fei,Huang, He,Hughes, Timothy,Xie, Yuxing,Xu, Jun,Yu, Yang,Zhang, Zhipeng
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supporting information
p. 4165 - 4173
(2020/07/14)
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- Cu(I)/chiral bisoxazoline-catalyzed enantioselective sommelet-hauser rearrangement of sulfonium ylides
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Catalytic asymmetric thia-Sommelet-Hauser rearrangement of sulfonium ylides remains a great challenge due to its multistep reaction mechanism involving metal carbene formation, proton transfer, and [2,3]-sigmatropic rearrangement. In particular, the key problem of such reactions is the differentiation of the enantiotopic lone pair electrons of sulfur, which generates the sulfonium ylide intermediate bearing chirality on the sulfur atom. With a modified chiral bisoxazoline ligand, we developed a Cu(I)- catalyzed asymmetric thia-Sommelet-Hauser rearrangement with good to excellent enantioselectivities. Mechanistic studies provide insights into the details of the reaction mechanism.
- Wang, Jianbo,Li, Shu-Sen
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supporting information
p. 12343 - 12358
(2020/11/10)
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- Catalyst-free, visible-light-promoted S-H insertion reaction between thiols and α-diazoesters
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A visible-light-promoted S-H insertion reaction between thiols and α-diazoesters was developed. The reaction proceeded smoothly at room temperature with a broad substrate scope, affording various thioethers in moderate to excellent yields. The catalyst- A
- Chen, Shuwen,Huo, Congde,Liu, Cai,Ma, Ben,Song, Menghui,Wang, Ganggang,Yang, Jingya,Zhou, Hongyan
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supporting information
p. 9494 - 9498
(2020/12/15)
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- Stoichiometric Photochemical Carbene Transfer by Bamford–Stevens Reaction
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The photolysis of diazoalkanes is a timely strategy to conduct carbene-transfer reactions under mild and metal-free reaction conditions, and has developed as an important alternative to conventional metal-catalyzed carbene-transfer reactions. One of the major limitations lies within the rapidly occurring side reaction of the carbene intermediate with remaining diazoalkane molecules that result in the use of an excess of the reaction partner and thus impacts on the reaction efficiency. Herein, we describe a protocol that takes advantage of the in situ generation of donor–acceptor diazoalkanes by Bamford–Stevens reaction. Following this strategy, the concentration of the diazoalkane reaction partner can be minimized to reduce unwanted side reactions and to now conduct photochemical carbene transfer reactions under stoichiometric reaction conditions. We have explored this approach in the C?H and N?H functionalization and cyclopropanation reaction of N-heterocycles and could demonstrate the applicability of this method in 51 examples.
- Aseeva, Polina,Empel, Claire,Jana, Sripati,Koenigs, Rene M.,Li, Fang,Verspeek, Dennis
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p. 2586 - 2591
(2020/03/04)
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- Triarylborane-Catalyzed Alkenylation Reactions of Aryl Esters with Diazo Compounds
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Herein we report a facile, mild reaction protocol to form carbon–carbon bonds in the absence of transition metal catalysts. We demonstrate the metal-free alkenylation reactions of aryl esters with α-diazoesters to give highly functionalized enyne products. Catalytic amounts of tris(pentafluorophenyl)borane (10–20 mol %) are employed to afford the C=C coupled products (31 examples) in good to excellent yields (36–87 %). DFT studies were used to elucidate the mechanism for this alkenylation reaction.
- Ariafard, Alireza,Babaahmadi, Rasool,Dasgupta, Ayan,Gierlichs, Lukas,Melen, Rebecca L.,Stefkova, Katarína
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supporting information
p. 15492 - 15496
(2020/07/20)
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- Copper-Catalyzed Carbene Insertion into the Sulfur-Sulfur Bond of RS-SCF 2 H/SCF 3 under Mild Conditions
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A copper-catalyzed carbene insertion into the sulfur-sulfur bond of trifluoromethyl/difluoromethyl/diphenyldisulfides under mild conditions has been developed. Diverse dithioketal derivatives were synthesized in moderate to good yields in an atom-economic
- Hong, Xin,Lu, Long,Shen, Qilong
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supporting information
p. 1602 - 1606
(2019/08/07)
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- Metal-Free Tandem Rearrangement/Lactonization: Access to 3,3-Disubstituted Benzofuran-2-(3H)-ones
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A novel metal-free synthesis of 3,3-disubstituted benzofuran-2-(3H)-ones through reacting α-aryl-α-diazoacetates with triarylboranes is presented. Initially, triarylboranes were successfully investigated in α-arylations of α-diazoacetates, however in the presence of a heteroatom in the ortho position, the boron enolate intermediate undergoes an intramolecular rearrangement to form a quaternary center. The intermediate cyclizes to afford valuable 3,3-disubstituted benzofuranones in good yields.
- Santi, Micol,Ould, Darren M. C.,Wenz, Jan,Soltani, Yashar,Melen, Rebecca L.,Wirth, Thomas
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supporting information
p. 7861 - 7865
(2019/04/25)
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- Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters
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This article describes the photoalkylation of electron-rich aromatic compounds with diazo esters. C-2-alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst loading is as low as 0.075 mol %. For EWG-substituted substrates, the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG- and EWG-EDG-substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway.
- Ciszewski, Lukasz W.,Durka, Jakub,Gryko, Dorota
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supporting information
p. 7028 - 7032
(2019/09/12)
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- Preparation of Organic Nitrates from Aryldiazoacetates and Fe(NO3)3·9H2O
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A thermal protocol is reported for the formal insertion of nitric acid into aryldiazoacetates using Fe(NO3)3·9H2O. This strategy is mild and high yielding and allows the preparation of a large variety of members of an unprecedented family of organic nitrates. The nitrate group can be also readily transformed into other functional groups and heterocyclic moieties and can possibly allow new biological explorations of untapped potential associated with their NO-releasing ability.
- Thurow, Samuel,Fernandes, Alessandra A. G.,Quevedo-Acosta, Yovanny,De Oliveira, Matheus F.,De Oliveira, Marcelo G.,Jurberg, Igor D.
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supporting information
p. 6909 - 6913
(2019/09/12)
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- Boron-Catalyzed C?C Functionalization of Allyl Alcohols
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Tris(pentafluorophenyl)borane-catalyzed C?C bond functionalization of arylallyl alcohols using donor-acceptor carbenes is presented. The allylic hydroxyl group is found to assist the product formation by neighboring group participation providing a clue towards mechanistic understanding. This method can also be employed to effect homologation of allyl alcohols to homoallyl alcohols. Overall, this metal-free transformation presents a novel disconnection strategy towards carbon-carbon bond scission and formation. (Figure presented.).
- Rao, Santhosh,Kapanaiah, Raja,Prabhu, Kandikere Ramaiah
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supporting information
(2019/02/14)
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