A Metal‐Free Amination of 1,2‐Diaza‐1,3‐dienes Using Hydrazine Hydrate Through <i>N−N</i> Bond Cleavage

Abstract Herein, we have developed a metal‐free, atom‐economical, intrinsically sustainable approach for synthesizing unprotected 4,5‐diamino pyrazoles from readily available 1,2‐diaza‐1,3‐dienes. This approach utilizes inexpensive hydrazine hydrate as the aminating source. Further, we have explored the reactivity of 4,5‐diamino pyrazole to synthesize fused pyrazolo[3,4‐ d ]‐1,2,3‐triazole heterocyclic compounds. We have also successfully demonstrated the synthetic utility of this methodology in synthesizing two drug analogs: analgesic difenamizole and anti‐psychotic CDPPB. The role of the phenyl ring of 3‐substituted‐1,2‐diaza‐1,3‐diene was explained with the help of control experimental and density functional theory (DFT) computation studies.