Copper‐Catalyzed Domino Synthesis of Spiropyrazoline Oxindoles via Condensation of Indolin‐2‐One and Phenylhydrazine Derivatives

Abstract We report a straightforward and efficient method for the synthesis of spiropyrazoline oxindoles using CuCl 2 as the Lewis acid catalyst. This approach involves a one‐pot domino process, consisting of a condensation step between indolin‐2‐one and phenylhydrazine derivatives, followed by a copper‐catalyzed cyclization reaction. The methodology enabled the synthesis of 34 diversely functionalized spiro compounds with yields ranging from moderate to excellent, achieving up to 98%.