Ruthenium-Catalyzed Azide-Alkyne Cycloaddition RuAAC

5 Ruthenium-Catalyzed Azide-Alkyne Cycloaddition (RuAAC) 

The Ruthenium-Catalyzed Azide-Alkyne Cycloaddition (RuAAC) complements the well-established CuAAC reaction, as the formation of 1,5-substituted triazoles (instead of 1,4-substituted 1,2,3-triazoles) can be achieved with high regioselectivity. In contrast to the CuAAC reaction, triazoles that are synthesized via RuAAC reaction can be formed from terminal as well as internal alkynes. This offers the possibility of the formation of fully-substituted triazoles. 

There are other characteristic properties that have to be considered concerning the RuAAC reaction  

Many aprotic solvents like THF, dioxane, toluene or DMF can be used for RuAAC, but protic solvents such as MeOH or PrOH result in reduced yields and the formation of side products. 

Present knowledge suggests that the RuAAC is not sensitive to reactions in the presence of atmospheric oxygen. 

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C. Ruthenium catalyzed azide-alkyne cycloaddition (RuAAC)... 

The regioselective formation of 1,4- and 1,5-disubstituted 1,2,3-triazoles can be accomplished by CuAAC reactions and ruthenium-catalyzed azide-alkyne [3+2] cycloaddition (RuAAC) reactions, respectively [69, 70]. Fokin and coworkers demonstrated that ruthenium complexes such as Cp RuCl(PPh3)2... 

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