NaNO₂/K₂S₂O₈‐mediated Selective Radical Nitration/Nitrosation of Indoles: Efficient Approach to 3‐Nitro‐ and 3‐Nitrosoindoles

Abstract

Abstract A mild and selective radical nitration/nitrosation of indoles with NaNO 2 using K 2 S 2 O 8 as oxidant is developed. Free (NH)‐indoles and N‐methyl indoles furnished 3‐nitro‐ and 3‐nitrosoindoles respectively, in good yields. Contrary to existing protocols, pyrrole selectively afforded 3‐nitropyrrole. Mechanistic studies showed that the reaction proceeded via an initial formation of nitroso/oxime intermediate, which is further oxidized to the corresponding 3‐nitroindole depending on the substitution on the indole N‐atom. Furthermore, synthetic transformations were carried out on the synthesized products towards accessing other valuable compounds. magnified image