Azobenzenes were readily acylated at the 2-position through a Pd-catalyzed C-H functionalization from simple aromatic azo compounds and aldehydes in good yields. The obtained acylated azobenzenes could be efficiently converted into the corresponding indazole derivatives in nearly quantitative yields.

A visible-light initiated oxidative cyclization of phenyl propiolates with sulfinic acids has been developed. The arylsulfonylation of alkynes was performed at room temperature under metal-free conditions to generate coumarin derivatives with wide functional group tolerance, good yields and high regioselectivity.

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 InCl(3)-catalyzed one-pot, three-component coupling of aldehyde, alkyne, and amine is proposed.