- Catalyst-Free and Redox-Neutral Innate Trifluoromethylation and Alkylation of Aromatics Enabled by Light
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The Minisci alkylation is useful to functionalize aromatics via alkyl radical addition. Current approaches to prepare alkyl radicals follow either oxidative or reductive pathways from various functional groups. Developing new strategy beyond these traditional methods remains elusive yet highly significant. In this article, we present a redox-neutral and catalyst-free protocol to engender alkyl radicals in the context of trifluoromethylation and general alkylation of arenes. This protocol, via the Norrish type I concept to produce alkyl radicals, accommodates various functional groups and delivers the product in good yields. This method identified a series of compounds as the trifluoromethylation and alkylation reagents assisted by light. It is expected that these compounds can find potential applications in other radical-involved reactions.
- Liu, Peng,Liu, Wenbo,Li, Chao-Jun
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supporting information
p. 14315 - 14321
(2017/10/17)
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- Rhodium-catalyzed α-methylthiolation reaction of unactivated ketones using 1,2-diphenyl-2-methylthio-1-ethanone for the methylthio transfer reagent
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In the presence of catalytic amounts of RhH(PPh3)4, 1,2-bis(diphenylphosphino)ethane (dppe), and dimethyl disulfide, ketones without α-activating groups were α-methylthiolated with 1,2-diphenyl-2-methylthio-1-ethanone giving α-methylthio ketones. The reaction of unsymmetrical ketones proceeded at the more substituted carbons. The initial formation of kinetic α-methylthiolated products followed by their rearrangement to thermodynamic products was observed in the reaction of α-phenyl ketones. Aldehydes, phenylacetate, and phenylacetonitrile were also α-methylthiolated under these conditions.
- Arisawa, Mieko,Toriyama, Fumihiko,Yamaguchi, Masahiko
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experimental part
p. 2305 - 2312
(2011/04/22)
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- Rhodium-catalyzed phenylthiolation reaction of heteroaromatic compounds using α-(phenylthio)isobutyrophenone
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In the presence of catalytic amounts of RhH(PPh3)4 and 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-benzothiazoles, 1,3-benzoxazoles, and benzothiophene reacted with α-(phenylthio) isobutyrophenone giving 2-phenylthio derivatives. Reactive monocyclic heteroaromatics, 1-methyl-1,2,3,4-tetrazole and 2-cyanothiophene were also converted into the 5-phenylthio derivatives. The use of an appropriate phenylthio transfer reagent is crucial for the efficient catalyzed conversion of heteroaromatic C-H bonds into C-S bonds.
- Arisawa, Mieko,Toriyama, Fumihiko,Yamaguchi, Masahiko
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supporting information; experimental part
p. 2344 - 2347
(2011/05/16)
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- Electrophilic substitutions with the electrogenerated sulfenium cation R1-S+
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The sulfenium cation R1-S+ electrogenerated by oxidation of organic disulfides, reacts with phenols, aromatic ethers and ketones bearing an hydrogen atom in α position, to give alkyl (aryl) sulfanyl compounds.
- Do, Quang Tho,Elothmani, Driss,Le Guillanton, Georges
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p. 4657 - 4658
(2007/10/03)
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- A Facile One-Pot Synthesis of Vicinal Di- and Triketones from α-Methylene Ketones by NBS-DMSO Oxidation
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The reaction of 1,2-diarylethanones (1a-u) with N-bromosuccinimide in anhydrous dimethyl sulphoxide afforded diarylethanediones (2a-u) in excellent yields.Under similar conditions, 1-phenyl-2-butanone (3) gave 1-phenyl-1,2-butanedione (4) in fair yield in addition to a small amount of 1-phenyl-3-methylthio-1,2-butanedione (5) and 1-phenyl-1-methylthio-2-butanone (6). 4-Phenyl-2-butanone (7), 1,3-diphenyl-2-propanone (9), and 1,3-diphenyl-1,3-propanedione (10) gave the corresponding triketones monohydrate (8) and (11). 1-Indanone (12), 2-indanone (13), and 1,3-indandione (14) gave ninhydrin (15) in good yields.In the case of 3-phenyl-1-indanone (16), 3-phenyl-2-bromo-1-indanone (17), 3-phenyl-2-bromo-1-indenone (18) and 3-phenyl-1-indenone (19) were obtained. 1-Phenyl-1-propanone (20) and 1-phenyl-1-butanone (22) gave the corresponding α-(methylthio)ketones (21) and (22). 1,3,3-Triphenylpropanone (24a) and 1-phenyl-3-methyl-1-butanone (24b) yielded only the corresponding α-bromoketones (25a,b) in good yields.These α-bromoketones, however, afforded the corresponding α-diketones (26a,b) in moderate yields when α-bromoketones reacted with dimethyl sulphoxide in the presence of AgBF4.
- Tatsugi, Jiro,Izawa, Yasuji
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p. 2747 - 2763
(2007/10/02)
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- REACTION OF ALDEHYDES AND KETONES WITH t-BUTYL BROMIDE-DIMETHYL SULPHOXIDE
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Reacting aldehydes and ketones with the "ButBr-Me2SO" system produces the corresponding α-bromoderivatives 2.In the case of ketones, where more than one regioisomer is possible, bromination is obtained exclusively at the more highly substituted α-position.With slight modifications of the reaction conditions (addition of Me2S, Me2SO) it is possible to obtain "in situ" formation of either dimethyl(2-oxo-phenylalkyl)sulphonium salts 3 or of α-methylthioderivatives 4.Dimethyl(1-methyl-2-oxo-2-phenylethyl)sulphonium bromide (3h) during crystallization undergoes spontaneous resolution of the two enantiomers, as demonstrated by single crystal X-ray analysis and absolute configuration assignment.
- Armani, E.,Dossena, A.,Marchelli, R.,Casnati, G.
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p. 2035 - 2040
(2007/10/02)
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