RSS-Feed abonnieren
DOI: 10.1055/s-0030-1258957
Synthesis of 1,5-Diaryl-1,2,3-triazoles Under Transition-Metal-Free Conditions
S. W. Kwok, J. R. Fotsing, R. J. Fraser, V. O. Rodionov, V. V. Fokin*
The Scripps Research Institute, La Jolla, USA
Publikationsverlauf
Publikationsdatum:
22. November 2010 (online)
![](https://www.thieme-connect.de/media/synfacts/201012/lookinside/thumbnails/10.1055-s-0030-1258957-1.jpg)
Significance
Reported is the synthesis of 1,5-diaryl-substituted 1,2,3-triazoles 3 from aryl azides 1 and terminal alkynes 2 under transition-metal-free conditions. The nucleophilic acetylide intermediate, prepared from terminal alkynes (S. Saito and co-workers J. Org. Chem. 2003, 68, 3702) without aggressive lithium or magnesium reagents, undergoes the reaction selectively with even modestly electrophilic organic azides producing 1,5-disubstituted triazoles 3. After screening of various hydroxide and alkoxide bases, the shorter reaction time and the experimental convenience of using aqueous base solution led to NMe4OH as the advantageous catalyst for practical reasons. Most aryl and heteroaryl azides and terminal alkynes participate in the 1,5-diaryl-substituted 1,2,3-triazoles 3 synthesis. Aryl azides with sterically demanding ortho substituents gave lower yields of products. Moreover, electronic properties of both reactants influence the outcome of the reaction significantly. Thus, 2 and 3 with EWGs reduce the nucleophilicity of the acetylide anion and the efficient triazenide cyclization step. Alkyl acetylenes failed to react under this condition due to their lower acidity.