Green Perspectives on Reaction Conditions

Cu(I) acetate is a very efficient catalyst for the reaction of phenylethyne and benzylazide, giving the desired product in 98% yield, in 8 min. The catalyst forms [(PhCtCCu)2] , while an equimolar amount of HOAc is produced, which promotes the reaction as mentioned earlier [7]. 

The readily available and inexpensive CU2O seems to be quite robust and catalyzes aqueous azide-alkyne cycloaddition reactions efficiently, even with very low loadings (ppm levels). A range of functional groups on the acetylene including halo-, cyclopropyl-, ethoxy-, amide, ether, and double bonds were well 

2 Copper(l) Complexes with Nitrogen- and Phosphorous-Donating Ligands 

A PTA-iminophosphorane Cu(I) complex (PTA= l,3,5-triaza-7-phosphaadamantane) also catalyzes the CuAAc reaction in aqueous media, as an example, the reaction of (azidomethyl)(phenyl)sulfane (PhSCH2Ng) and 

Nitrogen-donating ligands are particularly promising as they form stable Cu(I) complexes. They stabilize the Cu(I) oxidation state and modulate the catalytic activity of the Cu center, allowing smoother reaction conditions and broader applicability. 

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