Palladium-Catalyzed Site-Selective Nitration of 1-Aryl-1H-indazole: A Direct Access to 1-(2-Nitroaryl)-1H-indazoles
Krishna Yadav1, Vijay Choudhary2, Jyoti Joshi1
1Department of Chemistry, Malaviya National Institute of Technology Jaipur, Jaipur, Rajasthan 302017, India.
Abstract:
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.
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