Manganese(II) Porphyrin and Cumyl Hydroperoxide: An Efficient Catalyst for Aryl‐Pentazole C−N Bond Cleavage

The selective cleavage of C−N bonds in N ‐containing compounds holds significant research value in organic synthesis, particularly for the synthesis of promising polynitrogen species. For instance, the discovery of the cyclo ‐pentazolate ( cyclo ‐N 5 − ) anion in 2017 as a result of cleavage of the C−N bond has sparked interest within the field of high energy density materials. However, previous methods using ferrous glycinate and m ‐chloroperoxybenzoic acid generated the cyclo ‐N 5 − anion in a low yield of 19.5 % after 24 hours, and the mechanism remained unclear. In this study, we developed an efficient catalytic system comprising Mn (II) tetraphenylporphyrin and cumyl hydroperoxide. This system enables the cyclo ‐N 5 − anion to be produced from 3,5‐dimethyl‐4‐hydroxyphenylpentazole in 35.4 % yield in 4 hours. Characterization of Mn(IV)‐oxo porphyrins, ⋅ CH 3 , and ⋅ C 8 H 8 ON 5 radicals provides evidence for the mechanism whereby the cyclo ‐N 5 − anion forms. Our study underscores the competitive potential of radical‐initiated selective C−N bonds cleavage in N ‐arylazoles and opens avenues for further exploration in this field.