In the next step, the obtained pyrazoloazides were reacted with different aromatic and aliphatic alkynes 20a-h in a copper-catalyzed azide-alkyne cycloaddition (CuAAC). All attempted reactions could be conducted under standard conditions using copper sulfate and sodium ascorbate in THF/water (depicted in and Figure ). For selected derivatives, 21sd and 21vg, crystals suitable for single-crystal X-ray diffraction could be obtained and confirmed the product structure with the presumed regioisomer (Scheme 3).