Study On Iridium(â…¢)-Catalyzed Direct C-H Sulfonamidation Of 2-Aryl-1,2,3-Triazole N-oxides

2-Substituted 1,2,3-triazoles have attracted increasing attention due to their special chemical and biological properties. Especially, 2-(2-amidoaryl)-1,2,3-triazoles have been widely applied in agrochemicals, dyes, pharmaceuticals and advanced functional materials. Recently, transition metal-catalyzed direct C-H amination is an effective procedure to build such a structure. Common amine sources have been successfully explored as effective coupling partners for this strategy, including modified amide or sulfamide, N-carboxylate or N-sulfonate, N-chloroamines, parent amines and so on. Stoichiometric or excess external oxidants are necessary in most cases when parent amines are employed as the starting materials. Although the use of preactivated amine precursors could avoid the use of external oxidants, an additional step is required to install the mask, which might produce stoichiometric by-products as waste. Therefore, it is desirable to efficiently realize the ortho-sulfonamidation of 2-aryl-1,2,3-triazoles.Herein, we present an iridium-catalyzed direct C-H sulfonamidation of 2-aryl-1,2,3-triazole N-oxides using sulfonyl azide as an amino source to release N2 as the sole by-product(Scheme 1). Introduce of the N-O group over-covered the regioselectivity problem of the reaction and mono-sulfonamidated products were obtained in excellent yields for most cases. Moreover, this reaction proceeded smoothly with low catalyst loading under external oxidant-free reaction conditions and the functional groups compatibility was good.According the results obtained and literatures, a reaction mechanism was proposed as follows(Scheme 2):...