A Metal-Free Amination of 1,2-Diaza-1,3-dienes Using Hydrazine Hydrate Through N-N Bond Cleavage

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.