Visible light-enabled sp3-C-H functionalization with chloro- and bromoalkynes: chemoselective route to vinylchlorides or alkynes
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 b...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article (Journal) |
| Language: | English |
| Published: |
May 29, 2020
|
| In: |
Chemistry - a European journal
Year: 2020, Volume: 26, Issue: 67, Pages: 15573-15580 |
| ISSN: | 1521-3765 |
| DOI: | 10.1002/chem.202001259 |
| Online Access: | Resolving-System, kostenfrei, Volltext: https://doi.org/10.1002/chem.202001259 Verlag, kostenfrei, Volltext: https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202001259 
|
| Author Notes: | Tapas Adak, Marvin Hoffmann, Sina Witzel, Matthias Rudolph, Andreas Dreuw, and A. Stephen K. Hashmi |
| Summary: | 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. |
|---|---|
| Item Description: | Im Titel erscheint die Ziffer 3 hochgestellt Gesehen am 03.11.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1521-3765 |
| DOI: | 10.1002/chem.202001259 |