Facile access to energetic materials based on bipyrazoles via skeletal editing

Abstract

Skeletal editing is a synthetic strategy that involves specific point modifications at the core of a molecule. This unique retrosynthetic logic approach not only provides a novel method for use in the late-stage modification of molecules but also opens entirely novel synthetic pathways for application in generating complex molecules. The structures of bipyrazoles exhibit high nitrogen contents, insensitivity, and good thermal stabilities, rendering them ideal energetic frameworks for use in preparing high energy density materials (HEDMs). However, the traditional synthesis of energetic materials based on bipyrazoles faces considerable challenges, such as numerous reaction steps, unstable intermediate products, and stringent reaction conditions. In this study, we report a skeletal editing strategy for the modular synthesis of bipyrazole energetic compounds. These skeletal editing transformations are efficient and scalable, and they provide a straightforward, broadly applicable means of synthesizing bipyrazole energetic compounds. Furthermore, 3,4′-bipyrazole frameworks can also be easily prepared via this strategy, whereas synthesizing this compound using other methods is challenging. Based on the 3,4′-bipyrazole framework, two novel energetic compounds are synthesized, and these compounds exhibit remarkable detonation properties and low sensitivities. This study reveals that skeletal editing via distinctive retrosynthetic logic offers new opportunities in designing and synthesizing HEDMs.