Metal-free para-selective C-H amination and azidation of N-arylhydroxylamines.

Abstract

Due to the universality of arylamine and arylazide building blocks in pharmaceuticals, natural products and functional materials, the formation of aryl C-N bonds from readily available materials appears to be highly appealing, especially for the exclusive regioselective C-H amination. Despite substantial advancements in the synthesis of aryl C-N bonds, achieving a general, efficient, and para-selective C-H amination under mild conditions remains a significant challenge. Here we showcase a fluorosulfuryl imidazolium triflate-mediated para-selective C-H amination of N-arylhydroxylamines employing primary and secondary amines, diphenylmethanimine and azides as nitrogen source, affording structurally diverse 1,4-diaminoarenes or para-azidoanilides in the absence of oxidants and transition-metal catalysts. This effective protocol exhibits exclusive para-selectivity and good functional group tolerance for both N-arylhydroxylamines and N-nucleophiles (>90 examples). DFT calculations have been performed to elucidate the high chemoselectivity observed amidst multiple nucleophilic and electrophilic species.