- Hypervalent Iodine(III)-Promoted Radical Oxidative C-H Annulation of Arylamines with α-Keto Acids
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A novel catalyst-free radical oxidative C-H annulation reaction of arylamines with α-keto acids toward benzoxazin-2-ones synthesis under mild conditions was developed. This hypervalent iodine(III)-promoted process eliminated the use of a metal catalyst or additive with high levels of functional group tolerance. Hypervalent iodine(III) was both an oxidant and a radical initiator for this reaction. The synthetic utility of this method was confirmed by the synthesis of the natural product cephalandole A.
- Long, Lipeng,Wang, Jieyan,Gu, Liuqing,Yang, Shiguang,Qiao, Liang,Luo, Guotian,Chen, Zhengwang
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p. 12084 - 12092
(2021/08/24)
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- Three-Component Synthesis of Quinolines Based on Radical Cascade Visible-Light Photoredox Catalysis
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Synthesis of highly substituted quinolines has been developed based on three-component radical cascade based on visible-light photoredox catalysis. This tandem coupling reaction has been coordinated to proceed with high chemoselectivity based on the differential electronic properties of coupling partners. Subjection of electron-rich β-aminoacrylates with electron-deficient halides and alkenes to the optimized conditions leads to the formation of quinolines in good yields after in situ oxidation of tetrahydroquinolines. Detailed mechanistic studies which reveal an unexpected reaction pathway is described. (Figure presented.).
- Choi, Jun-Ho,Park, Cheol-Min
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supporting information
p. 3553 - 3562
(2018/09/22)
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- Synthesis of trifluoromethylated 2H-azirines through Togni reagent-mediated trifluoromethylation followed by PhIO-mediated azirination
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The reaction of enamine compounds with the Togni reagent in the presence of CuI afforded β-trifluoromethylated enamine intermediates, which were converted directly to biologically interesting trifluoromethylated 2H-azirines by an iodosobenzene (PhIO)-mediated intramolecular azirination in a one-pot process.
- Sun, Jiyun,Zhen, Xiaohua,Ge, Huaibin,Zhang, Guangtao,An, Xuechan,Du, Yunfei
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supporting information
p. 1452 - 1458
(2018/07/05)
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- One-pot synthesis of hypervalent iodine reagents for electrophilic trifluoromethylation
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Simplified syntheses suited for large scale preparations of the two hypervalent iodine reagents 1 and 2 for electrophilic trifluoromethylation are reported. In both cases, the stoichiometric oxidants sodium metaperiodate and tert-butyl hypochlorite have been replaced by trichloroisocyanuric acid. Reagent 1 is accessible in a one-pot procedure from 2-iodobenzoic acid in 72% yield. Reagent 2 was prepared via fluoroiodane 11 in a considerably shorter reaction time and with no need of an accurate temperature control.
- Matousek, Vaclav,Pietrasiak, Ewa,Schwenk, Rino,Togni, Antonio
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p. 6763 - 6768
(2013/07/26)
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- Iron(II)-catalyzed trifluoromethylation of potassium vinyltrifluoroborates
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Exchanging BF3 by CF3: The title reaction proceeds under exceedingly mild reaction conditions and provides 2-arylvinyl- and 2-heteroarylvinyl-substituted substrates with E/Z selectivities of more than 95:5. Experimental observations suggest that the reaction does not proceed through a transmetalation of the RBF3K species to the iron catalyst. Copyright
- Parsons, Andrew T.,Senecal, Todd D.,Buchwald, Stephen L.
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supporting information; experimental part
p. 2947 - 2950
(2012/05/05)
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- Copper-catalyzed trifluoromethylation of unactivated olefins
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Activating the inactive: A copper-catalyzed allylic trifluoromethylation of unactivated terminal olefins proceeds under mild conditions to produce linear allylic trifluoromethylated products with high E/Z selectivity (see scheme). The reaction can be applied to a range of substrates bearing numerous functional groups. Furthermore, the reaction is scalable and amenable to a benchtop setup. Copyright
- Parsons, Andrew T.,Buchwald, Stephen L.
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supporting information; experimental part
p. 9120 - 9123
(2011/10/13)
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- New hypervalent iodine reagents for electrophilic trifluoromethylation and their precursors: Synthesis, structure, and reactivity
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Several new five- and a six-membered heterocyclic monochloroiodanes, including two cationic species, were synthesized. Three of which were used for the preparation of corresponding trifluoromethylation reagents. These compounds were characterized by X-ray crystallography for a comparative structural study. A reactivity study on the trifluoromethylation of para-toluenesulfonic acid has been conducted in order to compare initial rates. Compounds having a longer I-O bond display a higher reactivity.
- Niedermann, Katrin,Welch, Jan M.,Koller, Raffael,Cvengro, Ján,Santschi, Nico,Battaglia, Philip,Togni, Antonio
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scheme or table
p. 5753 - 5761
(2010/09/18)
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- Reactivity of a 10-I-3 hypervalent iodine trifluoromethylation reagent with phenols
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(Chemical Equation Presented) The reaction of the 10-I-3 hypervalent iodine electrophilic trifluoromethylation reagent 1-trifluoromethyl-1,2-benziodoxol-3- (1H)-one (2) with 2,4,6-trimethylphenol, after deprotonation with NaH and in the presence of 18-crown-6 in a polar, nonprotic solvent, affords 1,3,5-trimethyl-2-(trifluoromethoxy)benzene (4) only as a byproduct. Trifluoromethylation occurs preferentially at the ortho- and para-positions of the aromatic core, giving the corresponding trifluoromethylcyclohexadienones 5 and 6. In case the ortho-and/or para-positions are not substituted, the corresponding products of an aromatic, electrophilic substitution are obtained in moderate yield, for example, 2-trifluoromethyl-4-tert-butylphenol (10a) from 4-tert-butylphenol (10).
- Stanek, Kyrill,Koller, Raffael,Togni, Antonio
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p. 7678 - 7685
(2008/12/22)
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- Recent advances in electrophilic CF3-transfer using hypervalent iodine(III) reagents
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The development of new methodologies for an efficient introduction of CF3 groups into complex molecules constitutes one of the most challenging tasks of modern organic chemistry. Recently, we reported the access to a new class of electrophilic CF3-transfer reagents based on hypervalent iodine. The versatile application of these reagents to C-centred nucleophiles, such as β-keto esters, silyl enol ethers and α-nitro esters, as well as to thiols and primary and secondary phosphines is described. Experiments with phenols afforded corresponding trifluomethylethers in very low yields. Schweizerische Chemische Gesellschaft.
- Kieltsch, Iris,Eisenberger, Patrick,Stanek, Kyrill,Togni, Antonio
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scheme or table
p. 260 - 263
(2009/04/07)
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- Novel 10-I-3 hypervalent iodine-based compounds for electrophilic trifluoromethylation
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The synthesis of a new family of 10-I-3 hypervalent iodine compounds is described in which the CF3 functionality participates directly in the hypervalent bond. These materials are accessible by nucleophilic ligand substitution at iodine using Me3SiCF3 in the presence of a substoichiometric amount of fluoride. The expected T-shaped geometry at iodine was verified by X-ray crystallographic analyses of three of the products (1-trifluoromethyl-1,2-benziodoxol-3-(1 H)-one and two substituted 1-trifluoromethyl-1,3-dihydro-1,2-benziodoxoles). Preliminary results for the direct electrophilic transfer of the trifluoromethyl moiety onto organic nucleophiles show modest reactivity in polar aprotic solvents under relatively mild conditions. The overall process can be understood as a formal umpolung of the CF3 group.
- Eisenberger, Patrick,Gischig, Sebastian,Togni, Antonio
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p. 2579 - 2586
(2008/02/04)
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