We report a palladium-catalyzed site-selective C–H nitration of 1-aryl-1H-indazoles enabled by newly developed Pd–organoselenium complexes. The protocol achieves highly efficient ortho-nitration of the aryl ring, delivering 1-(2-nitroaryl)-1H-indazoles in good to excellent yields and with selectivity complementary to previous indazole-C3, C4, and C7 nitration methods. Broad functional-group compatibility is observed across diverse substrates. Mechanistic studies indicate a ligand-controlled radical pathway responsible for the selectivity. The synthetic value of the nitrated products is demonstrated through their transformation into structurally diverse compounds, establishing this method as a practical route to valuable indazole scaffolds.
Yadav et al. (Mon,) studied this question.