Site-selective direct nitration of 2H-indazoles: easy access to 7-nitroindazoles

A new site-selective methodology for C–H nitration of 2H-indazoles has been accomplished at the C7 position using iron(iii) nitrate. This strategy enables practical access to an array of 7-nitroindazoles with broad functional group tolerance in good yields. The synthesized products have been proven as valuable synthetic intermediates by demonstrating the synthetic utility. Mechanistic investigations indicate that the reaction goes through a radical pathway.