- Visible-Light-Induced Remote C(sp3)-H Pyridylation of Sulfonamides and Carboxamides
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Visible-light-induced site-selective C(sp3)-H pyridylation of amides has been accomplished using N-amidopyridinium salts. The N-centered radicals generated by the single-electron reduction of N-amidopyridinium substrates undergo 1,5-hydrogen at
- Kim, Namhoon,Lee, Changseok,Kim, Taehwan,Hong, Sungwoo
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- Regiodivergent Conversion of Alkenes to Branched or Linear Alkylpyridines
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Herein we report a practical protocol for the visible-light-induced regiodivergent radical hydropyridylation of unactivated alkenes using pyridinium salts. This approach provides a unified synthetic platform to control the regioselectivity of the synthesis of linear or branched C4-alkylated pyridines. A remarkable selectivity switch from the anti-Markovnikov to the Markovnikov product can be achieved by the addition of tetrabutylammonium bromide. The versatility of this protocol is further demonstrated based on the late-stage functionalization in pharmaceuticals.
- Kim, Minseok,Shin, Sanghoon,Koo, Yejin,Jung, Sungwoo,Hong, Sungwoo
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supporting information
p. 708 - 713
(2022/01/20)
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- Micellar Catalysis: Visible-Light Mediated Imidazo[1,2-a]pyridine C—H Amination with N-Aminopyridinium Salt Accelerated by Surfactant in Water
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A light-promoted metal-free protocol for the amination of imidazo[1,2-a]pyridines with N-aminopyridinium salt by the assistance of surfactants in water was reported, charactering mild and environmentally benign conditions, as well as great functional grou
- Yang, Zhonglie,Cao, Kun,Peng, Xiaoyan,Lin, Li,Fan, Danchen,Li, Jun-Long,Wang, Jingxia,Zhang, Xiaobin,Jiang, Hezhong,Li, Jiahong
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supporting information
p. 3347 - 3352
(2021/10/20)
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- Visible-Light-Induced ortho-Selective Migration on Pyridyl Ring: Trifluoromethylative Pyridylation of Unactivated Alkenes
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The photocatalyzed ortho-selective migration on a pyridyl ring has been achieved for the site-selective trifluoromethylative pyridylation of unactivated alkenes. The overall process is initiated by the selective addition of a CF3 radical to the alkene to provide a nucleophilic alkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho-position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well-suited for addition to the C2-position of pyridinium salts to ultimately provide synthetically valuable C2-fluoroalkyl functionalized pyridines. Moreover, the method was successfully applied to the reaction with P-centered radicals. The utility of this transformation was further demonstrated by the late-stage functionalization of complex bioactive molecules.
- Jeon, Jinwon,He, Yu-Tao,Shin, Sanghoon,Hong, Sungwoo
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supporting information
p. 281 - 285
(2019/11/26)
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- Visible-Light-Enabled Ortho-Selective Aminopyridylation of Alkenes with N-Aminopyridinium Ylides
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By utilizing an underexplored reactivity mode of N-aminopyridinium ylides, we developed the visible-light-induced ortho-selective aminopyridylation of alkenes via radical-mediated 1,3-dipolar cycloaddition. The photocatalyzed single-electron oxidation of N-aminopyridinium ylides generates the corresponding radical cations that enable previously inaccessible 1,3-cycloaddition with a broader range of alkene substrates. The resulting cycloaddition adducts rapidly undergo subsequent homolytic cleavage of the N-N bond, conferring a substantial thermodynamic driving force to yield various β-aminoethylpyridines. Remarkably, amino and pyridyl groups can be installed into both activated and unactivated alkenes with modular control of ortho-selectivity and 1,2-syn-diastereoselectivity under metal-free and mild conditions. Combined experimental and computational studies are conducted to clarify the detailed reaction mechanism and the origins of site selectivity and diastereoselectivity.
- Moon, Yonghoon,Lee, Wooseok,Hong, Sungwoo
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supporting information
p. 12420 - 12429
(2020/07/24)
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- Alkene functionalization for the stereospecific synthesis of substituted aziridines by visible-light photoredox catalysis
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A novel strategy involving visible-light-induced functionalization of alkenes for the synthesis of substituted aziridines was developed. The readily prepared N-protected 1-aminopyridinium salts were used for the generation of N-centered radicals. This approach allowed the synthesis of aziridines bearing various functional groups with excellent diastereoselectivity under mild conditions. Moreover, this protocol was successfully applied to prepare structurally diverse nitrogen-containing frameworks.
- Yu, Wan-Lei,Chen, Jian-Qiang,Wei, Yun-Long,Wang, Zhu-Yin,Xu, Peng-Fei
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supporting information
p. 1948 - 1951
(2018/03/01)
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- Regiospecific Three-Component Aminofluorination of Olefins via Photoredox Catalysis
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Direct visible-light-mediated aminofluorination of styrenes has been developed with high regioselectivity. Shelf-stable N-Ts-protected 1-aminopyridine salt was used as the nitrogen-radical precursor, and the commercially available hydrogen fluoride-pyridi
- Mo, Jia-Nan,Yu, Wan-Lei,Chen, Jian-Qiang,Hu, Xiu-Qin,Xu, Peng-Fei
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supporting information
p. 4471 - 4474
(2018/08/07)
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- Visible-Light-Induced Aza-Pinacol Rearrangement: Ring Expansion of Alkylidenecyclopropanes
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A novel visible-light-induced aza-pinacol rearrangement was developed for the first time. In this approach, the addition of the N-centered radical to the C=C bond of alkylidenecyclopropanes delivers a variety of cyclobutanimines and γ-butyrolactones, with
- Liu, Wen-Deng,Xu, Guo-Qiang,Hu, Xiu-Qin,Xu, Peng-Fei
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supporting information
p. 6288 - 6291
(2017/12/08)
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- METHOD FOR PRODUCING COMPOUND HAVING 1,2-AMINO ALCOHOL SKELETON
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PROBLEM TO BE SOLVED: To provide a method for producing 1,2-amino alcohols that has a high regioselectivity and is safe and efficient. SOLUTION: Provided is a method for producing 1,2-amino alcohols represented by formula 3 below by letting an electrophil
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Paragraph 0074
(2017/01/31)
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- Regiospecific Intermolecular Aminohydroxylation of Olefins by Photoredox Catalysis
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A simple and regiospecific aminohydroxylation of olefins by photoredox catalysis has been developed. N-protected 1-aminopyridinium salts are the key compounds and serve as amidyl radical precursors by the action of Ir photocatalysts, fac-[Ir(ppy)3/s
- Miyazawa, Kazuki,Koike, Takashi,Akita, Munetaka
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supporting information
p. 11677 - 11680
(2015/08/11)
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- Synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyridinedicarboxylate
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Two syntheses of 7-trifluoromethylpyrazolo[1,5-a]pyridine dicarboxylate have been described. Approach A utilizes a nucleophilic addition of a trifluoromethyl group to N-p-toluenesulfonyliminopyridinium ylide followed by aromatization and subsequent cycloaddition with diethyl acetylenedicarboxylate to give 1b in modest yield. Approach B involves a selective zincation of pyrazolopyridine dicarboxylate at the C7 position with (TMP) 2Zn·2LiCl·2MgCl2 followed by iodination and trifluoromethylation to give 1b in good yield. The process in approach B has been successfully demonstrated on scale.
- Chong, Pek,Davis, Roman,Tabet, Elie,Elitzin, Vassil,Hatcher, Mark,Liu, Bing,Salmons, Matthew
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p. 6786 - 6788,3
(2012/12/13)
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- Aryne [3 + 2] cycloaddition with N-sulfonylpyridinium imides and in situ generated N-sulfonylisoquinolinium imides: A potential route to pyrido[1,2-b]indazoles and indazolo[3,2-a]isoquinolines
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The aryne [3 + 2] cycloaddition process with pyridinium imides breaks the aromaticity of the pyridine ring. By equipping the imide nitrogen with a sulfonyl group, the intermediate readily eliminates a sulfinate anion to restore the aromaticity, leading to the formation of pyrido[1,2-b]indazoles. The scope and limitation of this reaction are discussed. As an extension of this chemistry, N-tosylisoquinolinium imides, generated in situ from N′-(2-alkynylbenzylidene)-tosylhydrazides via an AgOTf-catalyzed 6-endo-dig electrophilic cyclization, readily undergo aryne [3 + 2] cycloaddition to afford indazolo[3,2-a]-isoquinolines in the same pot, offering a highly efficient route to these potential anticancer agents.
- Zhao, Jingjing,Li, Pan,Wu, Chunrui,Chen, Hongli,Ai, Wenying,Sun, Renhong,Ren, Hailong,Larock, Richard C.,Shi, Feng
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supporting information; experimental part
p. 1922 - 1930
(2012/04/23)
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- Gold-catalyzed nitrene transfer to activated alkynes: Formation of α,β-unsaturated amidines
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A gold-catalyzed intermolecular nitrene transfer to alkynes was developed for the first time, revealing a new mode of nitrene transfer and providing a novel access to versatile α-imino metal carbenes. Various mild nitrene-transfer reagents were examined, and iminopyridium ylides especially those based on 3,5-dichloropyridine proved be highly effective. With activated alkynes such as N-alkynyloxazolidinones as substrates, α,β- unsaturated amidines were formed in mostly good yields.
- Li, Chaoqun,Zhang, Liming
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supporting information; experimental part
p. 1738 - 1741
(2011/05/11)
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- Iron(II)-catalyzed amidation of aldehydes with iminoiodinanes at room temperature and under microwave-assisted conditions
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A method for the amidation of aldehydes with PhI=NTs/PhI=NNs as the nitrogen source and an inexpensive iron(II) chloride + pyridine as the in situ formed precatalyst under mild conditions at room temperature or microwave assisted conditions is described. The reaction was operationally straightforward and accomplished in moderate to excellent product yields (20-99%) and with complete chemoselectivity with the new C-N bond forming only at the formylic C-H bond in substrates containing other reactive functional groups. By utilizing microwave irradiation, comparable product yields and short reaction times of 1 h could be accomplished. The mechanism is suggested to involve insertion of a putative iron-nitrene/imido group to the formylic C-H bond of the substrate via a H-atom abstraction/radical rebound pathway mediated by the precatalyst [Fe(py)4Cl2] generated in situ from reaction of FeCl 2 with pyridine.
- Ton, Thi My Uyen,Tejo, Ciputra,Tania, Stefani,Chang, Joyce Wei Wei,Chan, Philip Wai Hong
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experimental part
p. 4894 - 4904
(2011/08/03)
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- Practical copper(I)-catalysed amidation of aldehydes
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The direct synthesis of amides by insertion into the C-H bond of aldehydes is shown to be a practical procedure through application of cheap, readily available catalysts generated in situ from copper(i) halides and pyridine. The Royal Society of Chemistry 2010.
- Chang, Joyce Wei Wei,Ton, Thi My Uyen,Tania, Stefani,Taylor, Paul C.,Chan, Philip Wai Hong
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supporting information; experimental part
p. 922 - 924
(2010/06/12)
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- Ruthenium(II)-porphyrin catalyzed selective N-imidation of aromatic nitrogen heterocycles
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Ruthenium(II)-porphyrin (0.5 mol%) catalyzed N-imidations of aromatic nitrogen heterocycles with phenyl(tosylimino)iodinane under mild conditions were achieved in good yields (94%). The effects of substituent, catalyst, temperature, and solvent on the re
- Jiang, Yan,Zhou, Guo-Chuan,He, Guang-Li,He, Ling,Li, Ju-An,Zheng, Shi-Long
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p. 1459 - 1464
(2008/02/05)
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- Facile amine formation by intermolecular catalytic amidation of carbon-hydrogen bonds
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A simple copper-based catalytic system has been developed for the carbon-hydrogen amidation reaction. The copper-homoscorpionate complex Tp Br3Cu(NCMe) catalyzes the transfer of the nitrene unit NTs (Ts = p-toluenesulfonyl) and its subsequent insertion into the sp3 C-H bonds of alkyl aromatic and cyclic ethers or the sp2 C-H bonds of benzene using PhI=NTs as the nitrene source, affording the corresponding trisubstitued NR1HTs amines in moderate to high yields. The use of the environmentally friendly chloramine-T has also proven effective, with the advantage that sodium chloride is formed as the only byproduct. A tandem, one-pot consecutive nitrene-carbene insertion system has been developed to yield amino acid derivatives.
- Fructos, Manuel R.,Trofimenko, Swiatoslaw,Mar Diaz-Requejo,Perez, Pedro J.
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p. 11784 - 11791
(2007/10/03)
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- Copper-catalyzed imination of pyridines using PhI=NTs as nitrene precursor
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The reaction of PhI=NTs with pyridines in the presence of a catalytic amount of Cu(II) triflate afforded the corresponding p-tolylsulfonyliminopyridinium ylides in excellent yields.
- Jain, Suman L.,Sharma, Vishal B.,Sain, Bir
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p. 4385 - 4387
(2007/10/03)
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- Azides: Part VII-Thermolysis of p-Toluenesulphonylazide and Ethyl Azidoformate in Pyridine and Its Derivatives; Evidence for an Electronic Equilibrium for N-Iminopyridinium Ylides
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The thermolysis of p-toluenesulphonylazide and ethyl azidoformate in pyridine, ethyl isonicotinate and 2,6-dicarbethoxypyridine has been studied.Thermal rearrangement to the corresponding diazepines via a diazanorcardiene intermediate can not be achieved either by the application of positive nitrogen pressure or in the presence of several high boiling solvents.The detailed IR, PMR and X-ray photoelectron spectral analyses of the N-iminopyridinium ylides reveal a new electronic configuration for the ylides.
- Ayyangar, N. R.,Bambal, R. B.,Srinivasan, K. V.
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- Investigation of Thermally Induced α-Deoxysilylation of Organosilylated Hydroxylamine Derivatives as a General Method for Nitrene Production
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A variety of organosilylated hydroxylamine derivatives have been synthesized and studied as possible nitrene generators by thermally induced α-deoxysilylation: GN(OR')SiR3 GN + R'OSiR3, where G = EtO2C, ArCO, ArSO2, Me, H, and Ph2PO.The methods used to assess nitrene formation include trapping product characterization, substitutent variation, kinetic activation parameter measurements, Hammett studies, and solvent effects.While the latter two types of precursors were only briefly investigated because of their marked resistance to fragmentation, the combined data for the remaining compounds are consistent with the intermediacy of a nitrene.The existence of alternative deoxysilylation pathways is discussed in some cases, and for comparison with the nitrogen systems reported herein, kinetic activation parameters for α-deoxysilylation about carbon and silicon have been determined.
- Chang, Young Hwan,Chiu, Fang-Ting,Zon, Gerald
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p. 342 - 354
(2007/10/02)
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- Psoralens
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New psoralen compounds have been synthesized. The compounds all include the addition of substituent groups at the 4'-position on the basic trioxsalen structure. Specifically, the compounds have the structure STR1 wherein STR2 where R is a mono or dicyclic radical which can contain one additional hetero atom in the nitrogen containing ring. The new substituted psoralens exhibit high solubility in aqueous solution and low dissociation constants from deoxyribonucleic acid (DNA), as well as a reactivity with ribonucleic acids (RNA).
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