- Generation of 1,3-Dimethylene-Substituted Isobenzofurans via Pd(II)-Catalyzed Selective Oxo-cyclization/SO2 Insertion Cascade of β-Alkynyl Ketones
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A new palladium(II)-catalyzed cyclization-radical addition cascade enables the direct construction of 1,3-dimethylene-substituted isobenzofuran derivatives containing a vinyl aryl sulfone unit in good yields by treating with β-alkynyl ketones, aryl diazonium salts, and DABCO·(SO2)2. The oxidant-free multicomponent reaction features good substrate scope and functional group tolerance, which proceeds through a sequence of Heck coupling, oxo-cyclization, and SO2 insertion.
- Liu, Shuai,Chen, Ke,Hao, Wen-Juan,Tu, Xing-Chao,Tu, Shu-Jiang,Jiang, Bo
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- Highly Efficient Synthesis of Hindered 3-Azoindoles via Metal-Free C-H Functionalization of Indoles
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Although 3-azoindoles have recently emerged as an appealing family of photoswitch molecules, the synthesis of such compounds has been poorly covered in the literature. Herein a high-yielding and operationally simple protocol is reported allowing the synthesis of 3-azoindoles, featuring important steric hindrance around the azo motif. Remarkably, this C-H coupling is characterized by excellent atom economy and occurs under metal-free conditions, at room temperature, and within few minutes, delivering the expected products in excellent yields (quantitatively in most of the cases). Accordingly, a library of new molecules, with potential applications as photochromic compounds, is prepared.
- Guillemard, Lucas,Jacob, Nicolas,Wencel-Delord, Joanna
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supporting information
p. 574 - 580
(2020/02/13)
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- Transition-Metal- A nd Light-Free Directed Amination of Remote Unactivated C(sp3)-H Bonds of Alcohols
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Due to the great value of amino alcohols, new methods for their synthesis are in high demand. Abundant aliphatic alcohols represent the ideal feedstock for the method development toward this important motif. To date, transition-metal-catalyzed approaches for the directed remote amination of alcohols have been well established. Yet, they have certain disadvantages such as the use of expensive catalysts and limited scope. Very recently, transition-metal-free visible-light-induced radical approaches have emerged as new powerful tools for directed remote amination of alcohols. Relying on 1,5-HAT reactivity, these methods are limited to β-or δ- A mination only. Herein, we report a novel transitionmetal- A nd visible-light-free room-temperature radical approach for remote β-, γ-, and δ-C(sp3)-N bond formation in aliphatic alcohols using mild basic conditions and readily available diazonium salt reagents.
- Kurandina, Daria,Yadagiri, Dongari,Rivas, Monica,Kavun, Aleksei,Chuentragool, Padon,Hayama, Keiichi,Gevorgyan, Vladimir
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p. 8104 - 8109
(2019/06/13)
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- Modular and Selective Arylation of Aryl Germanes (C?GeEt3) over C?Bpin, C?SiR3 and Halogens Enabled by Light-Activated Gold Catalysis
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Selective C (Formula presented.) –C (Formula presented.) couplings are powerful strategies for the rapid and programmable construction of bi- or multiaryls. To this end, the next frontier of synthetic modularity will likely arise from harnessing the coupling space that is orthogonal to the powerful Pd-catalyzed coupling regime. This report details the realization of this concept and presents the fully selective arylation of aryl germanes (which are inert under Pd0/PdII catalysis) in the presence of the valuable functionalities C?BPin, C?SiMe3, C?I, C?Br, C?Cl, which in turn offer versatile opportunities for diversification. The protocol makes use of visible light activation combined with gold catalysis, which facilitates the selective coupling of C?Ge with aryl diazonium salts. Contrary to previous light-/gold-catalyzed couplings of Ar–N2+, which were specialized in Ar–N2+ scope, we present conditions to efficiently couple electron-rich, electron-poor, heterocyclic and sterically hindered aryl diazonium salts. Our computational data suggest that while electron-poor Ar–N2+ salts are readily activated by gold under blue-light irradiation, there is a competing dissociative deactivation pathway for excited electron-rich Ar–N2+, which requires an alternative photo-redox approach to enable productive couplings.
- Dahiya, Amit,Fricke, Christoph,Funes-Ardoiz, Ignacio,Gevondian, Avetik G.,Schoenebeck, Franziska,Sherborne, Grant J.
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supporting information
p. 15543 - 15548
(2020/06/22)
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- Preparation of N-Arylquinazolinium Salts via a Cascade Approach
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An easy manipulation method for the preparation of N-arylquinazolinium salts is described from readily available aryldiazonium salts, nitriles, and 2-aminoarylketones in a one-pot operation. This method relies on the in situ generation of the N-arylnitrilium intermediate from the reaction of aryldiazonium salt with nitrile, which undergoes amination/cascade cyclization/aromatization, leading to N-arylquinazolinium salts in excellent yields. Nucleophilic addition of alkoxide to these N-arylquinazolinium salts provides functionalized dihydro-N-arylquinazoline.
- Ramanathan, Mani,Wan, Jing,Liu, Shiuh-Tzung
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p. 7459 - 7467
(2019/06/14)
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- Electrochemical Cross-Coupling of C(sp2)?H with Aryldiazonium Salts via a Paired Electrolysis: an Alternative to Visible Light Photoredox-Based Approach
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Photoredox-based C?H bond functionalization constitutes one of the most powerful and atom-economical approaches to organic syntheses. During this type of reaction, single electron transfer takes place between the photocatalyst (PC) and redox- active substrates. Electrosynthesis also involves electron transfer between substrates and electrodes. In this paper, we focus upon electrochemical cross-coupling of C(sp2)?H with aryldiazonium salts and have developed an efficient electrochemical approach to the Minisci-type arylation reaction. The constant current paired electrosynthesis proceeds in a simple undivided cell without external supporting electrolyte, features a wide range of substrates and is easy to scale-up. These results demonstrate that photoredox-based cross-coupling of C(sp2)?H with aryldiazonium salts can also proceed successfully under paired electrolysis conditions, thereby contributing to understanding of the parallels between photosynthesis and electrosynthesis. (Figure presented.).
- Jiang, Yang-ye,Dou, Gui-yuan,Zhang, Luo-sha,Xu, Kun,Little, R. Daniel,Zeng, Cheng-chu
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supporting information
p. 5170 - 5175
(2019/11/13)
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- Additions to N-Sulfinylamines as an Approach for the Metal-free Synthesis of Sulfonimidamides: O-Benzotriazolyl Sulfonimidates as Activated Intermediates
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Sulfonimidamides are obtained in moderate to very good yields from the key intermediates O-benzotriazolyl sulfonimidates, which are formed by reacting aryldiazonium tetrafluoroborates, N-tritylsulfinylamine, and N-hydroxybenzotriazole hydrate in a process mediated by a tertiary amine. The formation of the sulfonimidate proceeds in inexpensive and environmentally benign dimethyl carbonate as the solvent, it does not require anhydrous conditions, and the product yields generally exceed 70 %. The substrate scope is broad, and a wide range of sensitive organic functionalities is well tolerated. The reactions probably proceed via aryl radicals formed from diazonium cations with assistance from both the tertiary amine and the sulfinylamine.
- Bremerich, Maximilian,Conrads, Christian M.,Langletz, Tim,Bolm, Carsten
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supporting information
p. 19014 - 19020
(2019/11/22)
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- Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethyl-silane: A general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer
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We show that cobalt bis(acetylacetonate) [Co(acac)2], tert-butyl hydroperoxide (TBHP), and triethylsilane (Et3SiH) constitute an inexpensive, general, and practical reagent combination to initiate a broad range of Markovnikov-selective alkene hydrofunctionalization reactions. These transformations are believed to proceed by cobalt-mediated hydrogen atom transfer (HAT) to the alkene substrate, followed by interception of the resulting alkyl radical intermediate with a SOMOphile. In addition, we report the first reductive couplings of unactivated alkenes and aryldiazonium salts by an HAT pathway. The simplicity and generality of the Co(acac)2–TBHP–Et3SiH reagent combination suggests it as a useful starting point to develop HAT reactions in complex settings.
- Ma, Xiaoshen,Herzon, Seth B.
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supporting information
p. 2259 - 2265
(2018/09/14)
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- Synthesis of Chiral Sulfonyl Lactones via Copper-Catalyzed Asymmetric Radical Reaction of DABCO?(SO2)
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In the present work, an asymmetric copper-catalyzed radical multi-component cascade reaction of an unsaturated carboxylic acid, aryldiazonium tetrafluoroborate, and DABCO?(SO2)2 (DABSO) has been developed for the enantioselective synthesis of sulfonyl lactones. In this reaction, this SO2 surrogate, DABSO was applied for the first time in the construction of chiral compounds. This multiple-step asymmetric radical reaction was carried out under mild conditions and tolerated a wide range of substrates, resulting in the corresponding sulfonyl lactones with up to 95% chemical yields and 88% ee. The current reaction enriches the research contents of DABSO, and provides a new and efficient strategy to chiral functionalized lactones bearing quarternary stereogenic center. (Figure presented.).
- Wang, Yang,Deng, Lingling,Zhou, Jie,Wang, Xiaochen,Mei, Haibo,Han, Jianlin,Pan, Yi
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supporting information
p. 1060 - 1065
(2018/01/22)
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- Visible-Light-Promoted C-H Arylation by Merging Palladium Catalysis with Organic Photoredox Catalysis
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The use of a dual palladium/organic photoredox catalytic system enables the directed arylation of arenes with aryldiazonium salts with a broad substrate scope at room temperature under mild reaction conditions. This study thus serves as not only an alternative route for the biaryl motifs but also a new example for the application of an organic photoredox catalyst.
- Jiang, Jian,Zhang, Wen-Man,Dai, Jian-Jun,Xu, Jun,Xu, Hua-Jian
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p. 3622 - 3630
(2017/04/11)
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- An unprecedentedly simple method of synthesis of aryl azides and 3-hydroxytriazenes
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Fischer's approach towards the synthesis of aryl azides and triazinoles from diazonium salts and hydroxylammonium chloride (phenylhydraxylamine) was reinvestigated and optimized. The new methodology enables the preparation of aryl azides and triazinoles in high yields in water at room temperature. The procedure is very simple, robust, easily scalable, reproducible, and "green".
- Gribanov, Pavel S.,Topchiy, Maxim A.,Golenko, Yulia D.,Lichtenstein, Yana I.,Eshtukov, Artur V.,Terekhov, Vladimir E.,Asachenko, Andrey F.,Nechaev, Mikhail S.
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supporting information
p. 5984 - 5988
(2018/06/06)
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- Dual visible light photoredox and gold-catalyzed arylative ring expansion
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A combination of visible light photocatalysis and gold catalysis is applied to a ring expansion-oxidative arylation reaction. The reaction provides an entry into functionalized cyclic ketones from the coupling reaction of alkenyl and allenyl cycloalkanols with aryl diazonium salts. A mechanism involving generation of an electrophilic gold(III)-aryl intermediate is proposed on the basis of mechanistic studies, including time-resolved FT-IR spectroscopy.
- Shu, Xing-Zhong,Zhang, Miao,He, Ying,Frei, Heinz,Toste, F. Dean
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supporting information
p. 5844 - 5847
(2014/05/20)
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- Chiral anion phase transfer of aryldiazonium cations: An enantioselective synthesis of C3-diazenated pyrroloindolines
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Herein is reported the first asymmetric utilization of aryldiazonium cations as a source of electrophilic nitrogen. This is achieved through a chiral anion phase-transfer pyrroloindolinization reaction that forms C3-diazenated pyrroloindolines from simple tryptamines and aryldiazonium tetrafluoroborates. The title compounds are obtained in up to 99% yield and 96% ee. The air- and water-tolerant reaction allows electronic and steric diversity of the aryldiazonium electrophile and the tryptamine core. Live and let diazene: Chiral anion phase transfer of aryldiazonium cations has been utilized to prepare C3-diazenated pyrroloindolines. The air- and water-tolerant reaction allows electronic and steric diversity in the aryldiazonium electrophile and the tryptamine core, with the products being obtained in up to 99% yield and 96% ee (MTBE=methyl tert-butyl ether).
- Nelson, Hosea M.,Reisberg, Solomon H.,Shunatona, Hunter P.,Patel, Jigar S.,Toste, F. Dean
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supporting information
p. 5600 - 5603
(2014/06/10)
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- An easy route to (hetero)arylboronic acids
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An unprecedented spontaneous reactivity between diazonium salts and diboronic acid has been unveiled, leading to a versatile arylboronic acid synthesis directly from (hetero)arylamines. This fast reaction (35 min overall) tolerates a wide range of functional groups and is carried out under very mild conditions. The radical nature of the reaction mechanism has been investigated.
- Erb, William,Hellal, Akila,Albini, Mathieu,Rouden, Jacques,Blanchet, Jerome
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supporting information
p. 6608 - 6612
(2014/06/09)
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- Sandmeyer trifluoromethylation of arenediazonium tetrafluoroborates
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Copper capabilities: Diazonium salts are converted into the corresponding trifluoromethyl derivatives in the presence of a trifluoromethyl-copper complex generated in situ from CuSCN and the inexpensive, easy-to-use trifluoromethylating reagent Me3Si-CF3 (see scheme). This Sandmeyer-type reaction allows the straightforward synthesis of trifluoromethylated arenes and heteroarenes from the corresponding amines. Copyright
- Danoun, Grégory,Bayarmagnai, Bilguun,Grünberg, Matthias F.,Goo?en, Lukas J.
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supporting information
p. 7972 - 7975
(2013/08/23)
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- A simple catalytic system based on PdCl2(CH3CN) 2 in water for cross-coupling reactions using diazonium salts
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Aryl-heteroaryl and heteroaryl-heteroaryl compounds are obtained through the Suzuki-Miyaura cross-coupling reactions between diazonium salts and potassium trifluoroborates using PdCl2(CH3CN)2 as the catalyst in water and in the absence of any additive, ligand or base. In addition, the same mild catalytic system is effective for the Matsuda-Heck reaction between several monoolefins with aryldiazonium salts.
- El Bakouri, Ouissam,Fernández, Martí,Brun, Sandra,Pla-Quintana, Anna,Roglans, Anna
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p. 9761 - 9765
(2013/10/22)
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- Asymmetric catalysis, part 108: Copper catalysts with optically active ligands in the enantioselective Meerwein arylation of activated olefins
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The copper-catalyzed Meerwein reaction of activated olefins with arenediazonium halides leads to a formal addition of aryl halide to the olefinic double bond. Methyl acrylate, p-tolyldiazonium tetrafluoroborate and tetrabutylammonium chloride in anhydrous acetonitrile were used as a model system, the product being methyl a-chloro-β-tolylpropionate. Applying a newly established methodology, the isolated diazonium tetrafluoroborate and an equivalent amount of tetrabutylammonium chloride were added to the olefin and the copper catalyst, containing optically active ligands, such as 2-and 2,6-pyridinyloxazolines and bisoxazolines. The low optical inductions obtained in the room temperature reaction could be raised to 8.7% ee in the low temperature variant at -40 °C. Two phenyl substituents in the neighborhood of the chiral centers in the bisoxazoline ligands of the catalyst and increasing steric bulk in the ester group of the substrate (methyl, ethyl, menthyl) increase the stereoselectivity of the Meerwein arylation. Replacement of the p-tolyldiazonium salt by the mesityldiazonium salt caused the optical induction in the formation of the corresponding mesityl product rise to 19.5% ee. Thus, though considered to be a radical reaction, the Meerwein arylation of activated olefins can be rendered enantioselective by using copper catalysts with optically active ligands.
- Brunner, Henri,Bluechel, Christian,Doyle, Michael P.
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- Influence of Steric and Electronic Effects on the Binding of Arenediazonium Cations to 18-Crown-6 in Methanol at 25 deg C
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Log K, ΔH, and TΔS values for the interaction of several arenediazonium salts with 18-crown-6 were determined in methanol at 25 deg C by the calorimetric titration technique.The complex of benzenediazonium cation with 18-crown-6 is enthalpy stabilized with log K = 2.50.Substitution of a methyl group onto the ortho position(s) of benzenediazonium cation results in a total loss of complex stability.Substitution of various groups onto the para position results in changes in complex stability according to the electronic effect exerted in the diazonium moiety.A linear Hammett relationship (ρ = 0.65) was found between log K and ?+p values associated with the para substituent.
- Izatt, R. M.,Lamb, J. D.,Swain, C. S.,Christensen, J. J.,Haymore, Barry L.
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p. 3032 - 3034
(2007/10/02)
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