Assembling high nitrogen isomeric energetic molecules via a lithium-mediated concerted [2 + 3] reaction of two diazo compounds.

• A novel lithium-mediated concerted [2 + 3] reaction yields two regioisomeric compounds. • Compounds 3a / 3b have the highest nitrogen content among isomerized energetic materials. • Compound 3a has comparable performances and lower sensitivities to RDX. • 1,5-Substituted tetrazoles show higher thermal stabilities and lower mechanical sensitivities than 2,5-substituted ones. The search for high nitrogen isomeric energetic molecules and comparison of their structure–property relationship are always attractive in the field of energetic materials. In this paper, a novel lithium-mediated concerted [2 + 3] reaction with two diazo compounds has been accomplished which leads to the simultaneous formation of two isomeric cyanotetrazoles (2a and 2b). The cyano group in cyanotetrazoles was further converted to tetrazole or tetrazole N -oxide to form tricyclic heterocyclic products (3a , 3b , 7a , and 7b). The energetic properties of the compounds were studied. A representative compound 3a (T d = 220 °C, D = 9052 m s−1, IS = 13 J, FS = 200 N) has better detonation performances, higher thermal stability and lower mechanical sensitivities than RDX, which is expected to serve as a potential energetic material. [ABSTRACT FROM AUTHOR]