Copper on Iron: Catalyst and Scavenger for Azide-Alkyne Cycloaddition

Dipolar cycloaddition of terminal alkynes and azides catalyzed by the Cu/Fe bimetallic system is reported. In the presence of a readily accessible nanosized copper source, the cycloaddition reaction can be easily achieved at ambient temperature with high efficiency. The product obtained from the reaction catalyzed by Cu/Fe contains significantly lower copper contaminants compared to various active homogeneous copper complexes. Iron not only behaves as support for copper, but acts as a redox scavenger, and reduces the copper contamination of the organic product.