Indium-Catalyzed Highly Efficient Three-Component Coupling of Aldehyde, Alkyne, and Amine via C-H Bond Activation

In this paper, indium(III) chloride was found to be a highly effective catalyst for the three-component coupling reactions of aldehydes, alkynes, and amines (A(3)-coupling) via C-H activation. The reactions could be applied to both aromatic and aliphatic aldehydes and alkynes. Nearly quantitative yields of the desired products were obtained in most cases. No cocatalyst or activator is required, and water is the only byproduct in the reactions. Furthermore, a tentative mechanism of the InCl3-catalyzed one-pot, three-component coupling of aldehyde, alkyne, and amine is proposed.