- Synthesis of Unsymmetrical 1,4-Dicarbonyl Compounds by Photocatalytic Oxidative Radical Additions
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Herein we report a photocatalytic oxidative radical addition reaction for the synthesis of unsymmetrical 1,4-dicarbonyl compounds. This reaction utilizes a desulfurization process to generate electrophilic radicals, which add to α-halogenated alkenes and undergo further oxidation to deliver 1,4-dicarbonyl compounds. This mild and highly efficient method provides a valuable alternative to known strategies.
- Dong, Ya,Li, Ruining,Zhou, Junliang,Sun, Zhankui
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supporting information
p. 6387 - 6390
(2021/08/23)
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- Chloride-tolerant gold(I)-catalyzed regioselective hydrochlorination of alkynes
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We have developed a highly regioselective homogeneous gold(I)-catalyzed anti-hydrochlorination of unactivated alkynes at room temperature. We have overcome the incompatibility between conventional cationic gold catalysts and chloride by using a hydrogen-b
- Ebule, Rene,Liang, Shengzong,Hammond, Gerald B.,Xu, Bo
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p. 6798 - 6801
(2017/11/09)
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- Partial Reduction and Selective Transfer of Hydrogen Chloride on Catalytic Gold Nanoparticles
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HCl in solution accepts electron density from Au NPs and partially reduces at room temperature, as occurs with other simple diatomic molecules, such as O2 and H2. The activation can be run catalytically in the presence of alkynes to give exclusively E-vinyl chlorides, after the regio- and stereoselective transfer of HCl. Based also on this method, vinyl chloride monomer (VCM) can be produced in a milder and greener way than current industrial processes.
- Oliver-Meseguer, Judit,Doménech-Carbó, Antonio,Boronat, Mercedes,Leyva-Pérez, Antonio,Corma, Avelino
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supporting information
p. 6435 - 6439
(2017/05/29)
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- Green and Efficient: Iron-Catalyzed Selective Oxidation of Olefins to Carbonyls with O2
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A mild and operationally simple iron-catalyzed protocol for the selective aerobic oxidation of aromatic olefins to carbonyl compounds is described. Catalyzed by a Fe(III) species bearing a pyridine bisimidazoline ligand at 1 atm of O2, α- and β-substituted styrenes were cleaved to afford benzaldehydes and aromatic ketones generally in high yields with excellent chemoselectivity and very good functional group tolerance, including those containing radical-sensitive groups. With α-halo-substituted styrenes, the oxidation took place with concomitant halide migration to afford α-halo acetophenones. Various observations have been made, pointing to a mechanism in which both molecular oxygen and the olefinic substrate coordinate to the iron center, leading to the formation of a dioxetane intermediate, which collapses to give the carbonyl product. (Chemical Equation).
- Gonzalez-De-Castro, Angela,Xiao, Jianliang
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p. 8206 - 8218
(2015/07/15)
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- Selective Ruthenium-Catalyzed Hydrochlorination of Alkynes: One-Step Synthesis of Vinylchlorides
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An unprecedented ruthenium-catalyzed direct and selective alkyne hydrochlorination is reported and leads to vinylchlorides in excellent yields with atom economy. The reaction proceeds at room temperature from terminal alkynes and provides a variety of chloroalkenes. Only the regioisomer resulting from the formal Markovnikov addition is selectively formed. Mechanistic studies show the stereoselective syn addition of HCl to alkynes at room temperature and suggest a chloro hydrido RuIV species as a key intermediate of the reaction.
- Dérien, Sylvie,Klein, Hubert,Bruneau, Christian
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supporting information
p. 12112 - 12115
(2015/10/12)
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- Direct preparation of vinyl halides from the corresponding ketones and acetyl halides
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Vinyl chlorides and bromides are obtained in good yield from the corresponding ketones and acetyl halides in the presence of trifluoroacetic or trifluoromethanesulfonic acid. The Z isomer is selectively formed.
- Moughamir, Khadija,Mezgueldi, Bouchra,Atmani, Aziz,Mestdagh, Helene,Rolando, Christian
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- Vinylcations, 39. Zinc Chloride Catalysed Addition of Hydrogen Chloride to Cyclopropylalkynes
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Zinc chloride catalysed addition of hydrogen chloride to 1-cyclopropylalkynes 5a-e (R = CH3, c-C3H5, phenyl, p-tolyl, 4-methoxyphenyl) is studied and the results are compared with those of the addition of HCl/ZnCl2 to several substituted arylalkynes 10a-h.Thus, the alkynes are reacted with HCl/ZnCl2 in dichloromethane and the reaction products are investigated also with respect to their stereochemistry.All alkynes yield predominantly the direkt hydrogen chloride addition products.The 1-cyclopropylalkynes 5a-d give (E)-1-chloro-1-cyclopropyl-1-alkenes 15, and (E)-1-chloro-2-cyclopropyl-1-(4-methoxyphenyl)ethene (16e) is obtained as the major product from 5e (R = 4-CH3OC6H4).Moreover, ring opening to homoallenyl chlorides 19 and, as a side reaction, formation of the ketones 17 and 18 by the addition of water are observed.In a secondary addition reaction, the dichlorides 20 are also obtained by homoallyl rearrangement.The arylalkynes 10a-g react preferentially with formation of (E)-1-aryl-1-chloroalkenes 21.Relative rates are obtained by inter- and intramolecular competition reactions of the alkynes 23 and 5b-e with HCl/ZnCl2 showing the order of stabilization by substituents of the intermediate vinyl cation 2 to be 4-ClC6H4 E2 mechanism.The preferential formation of the addition products E-15, E-16, and E-21 is attributed to a syn-vinyl cation ion pair and to steric approach control of the β-substituents in the vinyl cation intermediate 2.
- Hanack, Michael,Weber, Erhard
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p. 777 - 797
(2007/10/02)
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- Intramolecular Diels-Alder Cycloadditions of Perchloro(allyloxy)- and Perchlorobis(allyloxy)cyclopentadienes
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The intramolecular cycloadditions of some mono(allyloxy)- and bis(allyloxy)perchlorocyclopentadienes have been carried out.Even in the case of trisubstituted olefins, this internal cycloaddition process occurs in good yield.The allyloxy compounds (10, 11,
- Jung, Michael E.,Light, Lynn A.
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p. 1084 - 1090
(2007/10/02)
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