- Photocatalytic Dehydrogenative Cross-Coupling of Alkenes with Alcohols or Azoles without External Oxidant
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Direct cross-coupling between alkenes/R-H or alkenes/RXH is a dream reaction, especially without external oxidants. Inputting energy by photocatalysis and employing a cobalt catalyst as a two-electron acceptor, a direct C?H/X?H cross-coupling with H2evolution has been achieved for C?O and C?N bond formation. A new radical alkenylation using alkene as the redox compound is presented. A wide range of aliphatic alcohols—even long chain alcohols—are tolerated well in this system, providing a new route to multi-substituted enol ether derivatives using simple alkenes. Additionally, this protocol can also be used for N-vinylazole synthesis. Mechanistic insights reveal that the cobalt catalyst oxidizes the photocatalyst to revive the photocatalytic cycle.
- Yi, Hong,Niu, Linbin,Song, Chunlan,Li, Yiying,Dou, Bowen,Singh, Atul K.,Lei, Aiwen
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- Regioselective and stereoselective entry to β,β-disubstituted vinyl ethers via the sequential hydroboration/Suzuki-Miyaura coupling of ynol ethers
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A highly regio- and stereoselective synthesis of stereodefined β,β-disubstituted alkenyl ethers featuring the sequential hydroboration/Suzuki-Miyaura coupling of ynol ethers has been described. A number of functional groups, including OMe, Ac, CO2Et, CN, halides, and alkyl, (hetero)aryl, and alkenyl groups, are well-tolerated under the reaction conditions. Furthermore, it allows a facile entry to the labile diarylacetaldehydes by TFA-mediated hydrolysis of β,β-disubstituted vinyl ethers.
- Cui, Weijian,Mao, Mengyi,He, Zuying,Zhu, Gangguo
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p. 9815 - 9821
(2013/10/22)
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- Ring-Splitting of 2,2-Diarylthiethane by Electron-Transfer Photosensitization of 9,10-Dicyanoanthracene
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A 9,10-dicyanoanthracene (DCA)-photosensitized reaction of 3-cyano- or 3-ethoxy-2,2-diarylthietane in acetonitrile gave selectively 2-cyano- or 2-ethoxy-1,1-diarylethene.The ring-splitting reaction proceeds via a one-electron oxidation of the sulfur atom of thietane ring by a photochemical electron transfer to the excited singlet state of DCA.
- Shima, Kensuke,Sazaki, Akira,Nakabayashi, Kenichi,Yasuda, Masahide
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p. 1472 - 1474
(2007/10/02)
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