Copper on Iron: Catalyst and Scavanger for Azide-Alkzne Cycloaddition, Szabolcs Kovács, Katalin Zih-Perényi, Ádám Révész, Zoltán Novák, Synthesis 2012; 44, 3722-3730. DOI: 10.1055/s-0032-1317697 | [Full Text Link] [Supp. Info Link]

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.