Visible light-enabled sp3-C-H functionalization with chloro- and bromoalkynes

• Verfasst von: Adak, Tapas [VerfasserIn]
• Verfasst von: Hoffmann, Marvin [VerfasserIn]
• Verfasst von: Witzel, Sina [VerfasserIn]
• Verfasst von: Rudolph, Matthias [VerfasserIn]
• Verfasst von: Dreuw, Andreas [VerfasserIn]
• Verfasst von: Hashmi, A. Stephen K. [VerfasserIn]
• Titel: Visible light-enabled sp3-C-H functionalization with chloro- and bromoalkynes
• Titelzusatz: chemoselective route to vinylchlorides or alkynes
• Verf.angabe: Tapas Adak, Marvin Hoffmann, Sina Witzel, Matthias Rudolph, Andreas Dreuw, and A. Stephen K. Hashmi
• E-Jahr: 2020
• Jahr: May 29, 2020
• Umfang: 8 S.
• Fussnoten: Im Titel erscheint die Ziffer 3 hochgestellt ; Gesehen am 03.11.2020
• Titel Quelle: Enthalten in: Chemistry - a European journal
• Ort Quelle: Weinheim : Wiley-VCH, 1995
• Jahr Quelle: 2020
• Band/Heft Quelle: 26(2020), 67, Seite 15573-15580
• ISSN Quelle: 1521-3765
• DOI: doi:10.1002/chem.202001259
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: C−H functionalization
• Sach-SW: hydroalkylation
• Sach-SW: photoorganocatalysis
• K10plus-PPN: 173762267X
• K10plus-PPN:
  Universitätsbibliothek
• Lokale URL UB: Zum Volltext

Abstract

An unprecedented direct atom-economic chemo- and regioselective hydroalkylation of chloroalkynes and an sp3-C−H alkynylation of bromoalkynes was achieved. The reaction partners are unfunctionalized ethers, alcohols, amides, and even non-activated hydrocarbons. We found that a household fluorescent bulb was able to excite a diaryl ketone, which then selectively abstracts a H-atom from an sp3-C−H bond. The product of a formal alkyne insertion into the sp3-C−H bond was obtained with chloroalkynes, providing valuable vinyl chlorides. The photo-organocatalytic hydrogen atom transfer strategy gives rise to a broad range of diversely functionalized olefins. When bromoalkynes are applied in the presence of a base, a chemoselectivity switch to an alkynylation is observed. This reaction can even be performed for the alkynylation of unactivated sp3-C−H bonds, in this case with a preference of the more substituted carbon. Accompanying quantum chemical calculations indicate a vinyl radical intermediate with pronounced linear coordination of the carbon radical center, thus enabling the formation of both diastereoisomers after H-atom abstraction, suggesting that the (Z)-diastereoisomer is preferred, which supports the experimentally observed (E/Z)-distribution.