Synthesis of Substituted Triazole-Pyrazole Hybrids using Triazenopyrazoles Precursors

A synthesis route to access triazole-pyrazole hybrids via pyrazolotriazenes was developed. Contrary to existing methods, this route allows the facile N-functionalization of the pyrazole before the attachment of the triazole unit via a copper-catalyzed azide-alkyne cycloaddition. The developed methodology was used to synthesize a library of over fifty novel multi-substituted pyrazole-triazole hybrids. We could also demonstrate a one-pot strategy that renders the isolation of potentially hazardous azides obsolete. In addition, the compatibility of the method with solid-phase synthesis was shown exemplarily.