Efficient copper-catalyzed tandem oxidative iodination and alkyne-azide cycloaddition in the presence of glycine-type ligands.

Tandem oxidative iodination and alkyne-azide cycloaddition reaction has provided one of the most widely used methods for preparation of 5-iodo-1,2,3-triazoles. However, stoichiometric copper salts are involved in this type of reaction in order to enhance the reaction effectiveness, which caused some problems related to toxic metal contaminations and less sustainability. In this paper, we described that a copper-catalyzed (10 mol%) tandem oxidative iodination and alkyne-azide cycloaddition could be completed in the presence of the newly-found glycine-type ligands with low-cost NaI as the iodine resource. In the novel reaction system, a wide range of terminal alkyne, organic azide and inexpensive iodide could react effectively in one pot to give structurally diverse 5-iodo-1,4-subsitutied 1,2,3-triazoles. Natural product derivatives and alkynyl pyridines that hardly react under traditional conditions could also be transferred smoothly to the target products for the first time. Image 1 • Catalytic amount of Cu(I) salt. • New Glycine-type ligand. • NaI as the low-cost iodine resource. • Wide scope of reactants. [ABSTRACT FROM AUTHOR]