Abstract
The catalytic activity of a series of ruthenium(II) complexes in azide-alkyne cycloadditions has been evaluated. The [Cp*RuCl] complexes, such as Cp*RuCl(PPh3)2, Cp*RuCI(COD), and Cp*RuCl(NBD), were among the most effective catalysts. In the presence of catalytic Cp*RuCI(PPh3)2 or Cp*RuCl(COD), primary and secondary azides react with a broad range of terminal alkynes containing a range of functionalities selectively producing 1,5-disubstituted 1,2,3-triazoles; tertiary azides were significantly less reactive. Both complexes also promote the cycloaddition reactions of organic azides with internal alkynes, providing access to fully-substituted 1,2,3-triazoles. The ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC) appears to proceed via oxidative coupling of the azide and alkyne reactants to give a six-membered ruthenacycle intermediate, in which the first new carbon-nitrogen bond is formed between the more electronegative carbon of the alkyne and the terminal, electrophilic nitrogen of the azide. This step is followed by reductive elimination, which forms the triazole product. DFT calculations support this mechanistic proposal and indicate that the reductive elimination step is rate-determining.
| Original language | English |
|---|---|
| Pages (from-to) | 8923-8930 |
| Number of pages | 8 |
| Journal | Journal of the American Chemical Society |
| Volume | 130 |
| Issue number | 28 |
| DOIs | |
| Publication status | Published - 16 Jul 2008 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Chemistry(all)
Cite this
Ruthenium-catalyzed azide-alkyne cycloaddition : Scope and mechanism. / Boren, Brant C.; Narayan, Sridhar; Rasmussen, Lars K.; Zhang, Li; Zhao, Haitao; Lin, Zhenyang; Jia, Guochen; Fokin, Valery V.
In: Journal of the American Chemical Society, Vol. 130, No. 28, 16.07.2008, p. 8923-8930.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Ruthenium-catalyzed azide-alkyne cycloaddition
T2 - Scope and mechanism
AU - Boren, Brant C.
AU - Narayan, Sridhar
AU - Rasmussen, Lars K.
AU - Zhang, Li
AU - Zhao, Haitao
AU - Lin, Zhenyang
AU - Jia, Guochen
AU - Fokin, Valery V.
PY - 2008/7/16
Y1 - 2008/7/16
N2 - The catalytic activity of a series of ruthenium(II) complexes in azide-alkyne cycloadditions has been evaluated. The [Cp*RuCl] complexes, such as Cp*RuCl(PPh3)2, Cp*RuCI(COD), and Cp*RuCl(NBD), were among the most effective catalysts. In the presence of catalytic Cp*RuCI(PPh3)2 or Cp*RuCl(COD), primary and secondary azides react with a broad range of terminal alkynes containing a range of functionalities selectively producing 1,5-disubstituted 1,2,3-triazoles; tertiary azides were significantly less reactive. Both complexes also promote the cycloaddition reactions of organic azides with internal alkynes, providing access to fully-substituted 1,2,3-triazoles. The ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC) appears to proceed via oxidative coupling of the azide and alkyne reactants to give a six-membered ruthenacycle intermediate, in which the first new carbon-nitrogen bond is formed between the more electronegative carbon of the alkyne and the terminal, electrophilic nitrogen of the azide. This step is followed by reductive elimination, which forms the triazole product. DFT calculations support this mechanistic proposal and indicate that the reductive elimination step is rate-determining.
AB - The catalytic activity of a series of ruthenium(II) complexes in azide-alkyne cycloadditions has been evaluated. The [Cp*RuCl] complexes, such as Cp*RuCl(PPh3)2, Cp*RuCI(COD), and Cp*RuCl(NBD), were among the most effective catalysts. In the presence of catalytic Cp*RuCI(PPh3)2 or Cp*RuCl(COD), primary and secondary azides react with a broad range of terminal alkynes containing a range of functionalities selectively producing 1,5-disubstituted 1,2,3-triazoles; tertiary azides were significantly less reactive. Both complexes also promote the cycloaddition reactions of organic azides with internal alkynes, providing access to fully-substituted 1,2,3-triazoles. The ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC) appears to proceed via oxidative coupling of the azide and alkyne reactants to give a six-membered ruthenacycle intermediate, in which the first new carbon-nitrogen bond is formed between the more electronegative carbon of the alkyne and the terminal, electrophilic nitrogen of the azide. This step is followed by reductive elimination, which forms the triazole product. DFT calculations support this mechanistic proposal and indicate that the reductive elimination step is rate-determining.
UR - http://www.scopus.com/inward/record.url?scp=47349098606&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=47349098606&partnerID=8YFLogxK
U2 - 10.1021/ja0749993
DO - 10.1021/ja0749993
M3 - Article
C2 - 18570425
AN - SCOPUS:47349098606
VL - 130
SP - 8923
EP - 8930
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 28
ER -