Radical-mediated C-N bond activation in 3,5-diamino-4-nitro-1H-pyrazole towards high-energy and insensitive energetic materials

C-N bond activation has been recognized as a powerful methodology in organic synthesis, but C-N bond activation on monocyclic rings remains an intractable challenge, due to the high energy barrier required for the dearomatization process. Now a facile and efficient nitrogen-centered-radical-mediated approach to cleave C-N bonds in a monocyclic pyrazole is described. Using N-bromosuccinimide as a radical initiator, C-N bond cleavage was achieved in yields up to 91%. This reaction Led to an important precursor (2), subsequently annulated and oxidized to an energetic compound 4, which exhibits promising application in balancing performances and thermal stabilities.