Single-Atom Skeletal Editing for One-Step Construction of 1,2,3-Triazine N-Oxide from Pyrimidine via C to N→O Transmutation

Single-atom skeletal editing, which focuses on the precise reconstruction of core frameworks in complex molecules, is of profound significance to synthetic chemistry. While previous studies have primarily focused on the deletion, insertion, or mutual transformation of atoms in aromatic rings, C-to-N→O single-atom transformation remains rare. Herein, an efficient one-step C to N→O transmutation is realized in the pyrimidine-fused ring, enabling construction of 1,2,3-triazine N-oxide. The mechanistic mechanism for this transformation has been substantiated for the first time through combined experimental and theoretical investigations. This process yielded two novel compounds, namely, the insensitive heat-resistant explosive 7-amino-2<i>H</i>-[1,2,3]triazolo[4,5-<i>d</i>][1,2,3]triazine 5-oxide (TTO) and the high-energy material 7-amino-2-(trinitromethyl)-2<i>H</i>-[1,2,3]triazolo[4,5-<i>d</i>][1,2,3]triazine 5-oxide (TNTTO). Additionally, TNTTO demonstrates remarkable laser ignition performance. This study has not only simplified the construction of 1,2,3-triazine N-oxide through the C to N→O single-atom transformation, but also provides a valuable extension to the skeletal editing strategy.