- Visible-Light-Promoted, Catalyst-Free Gomberg-Bachmann Reaction: Synthesis of Biaryls
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Biaryls were synthesized via a novel visible-light-promoted Gomberg-Bachmann reaction that does not require a photosensitizer or any metal reagents. The formation of an electron donor-acceptor complex between aryl diazonium salts and pyridine allows, under visible-light irradiation, the synthesis of biaryls in moderate-to-high yields.
- Lee, Juyoung,Hong, Boseok,Lee, Anna
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p. 9297 - 9306
(2019/08/12)
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- Mild, visible light-mediated decarboxylation of aryl carboxylic acids to access aryl radicals
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Herein we present the first example of aryl radical formation via the visible light-mediated decarboxylation of aryl carboxylic acids using photoredox catalysis. This method constitutes a mild protocol for the decarboxylation of cheap and abundant aryl carboxylic acids and tolerates both electron-rich substrates and those lacking ortho-substitution. The in situ formation of an acyl hypobromite is proposed to prevent unproductive hydrogen atom abstraction and trapping of the intermediate aroyloxy radical, enabling mild decarboxylation.
- Candish,Freitag,Gensch,Glorius
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p. 3618 - 3622
(2017/07/11)
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- Three-component coupling based on flash chemistry. Carbolithiation of benzyne with functionalized aryllithiums followed by reactions with electrophiles
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A flow microreactor method for three-component coupling of benzyne was developed based on flash chemistry. o-Bromophenyllithium generated from 1-bromo-2-iodobenzene and a functionalized aryllithium generated from the corresponding aryl halide were mixed at -70 °C. In the subsequent reactor o-bromophenyllithium is decomposed to generate benzyne without affecting the functionalized aryllithium at -30 °C, and carbolithiation of benzyne with the aryllithium took place spontaneously. The resulting functionalized biaryllithium was reacted with an electrophile in the subsequent reactor to give the corresponding three-component coupling product. The precise optimization of reaction conditions using the temperature-residence time mapping is responsible for the success of the present transformation. The present method has been successfully applied to the synthesis of boscalid.
- Nagaki, Aiichiro,Ichinari, Daisuke,Yoshida, Jun-Ichi
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supporting information
p. 12245 - 12248
(2014/11/08)
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- Aryl radicals from hexazadienes and tetrazenes
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Aryl radicals are produced from both ends of the hexazadienes 1 and 2 and from the tetrazene 3, either thermally or photolytically.They attack aromatic compounds in the nucleus, the yield of biaryl being in the range 40-70percent, though it can be made nearly quantitative by using m-dinitrobenzene as additive.The aryl radicals also oxidize 2-propanol to acetone, the reaction products being the halogenobenzene and 1,2-diacetylhydrazine.Photolysis of 1 goes mainly by way of the tetrazene 3, and this may also be a significant pathway in the thermal reaction.Azodiacetylis an intermediate in the thermal reaction of 1 with 2-propanol and may be generally so in all its reactions.Radical induced decomposition is believed to be important in the reactions of 1, 2, and 3, and it is probably responsible for the formation of 1-acetyl-1-arylhydrazines, routinely produced in yields up to 25percent.
- Mackay, Donald,McIntyre, Deane Douglas
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p. 990 - 999
(2007/10/02)
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