Sustainable Catalyst‐Free Synthesis of Substituted Pyrazoles Through an Annulation/Oxidation Cascade Under Batch and Continuous‐Flow Methods

We describe a catalyst‐free synthesis of substituted pyrazoles in good to excellent yields using α,β‐unsaturated β‐ketoesters and aryl hydrazines under mild reaction conditions. The reaction proceeds through a Michael‐initiated ring closure reaction followed by in situ oxidation. A broad range of substrates bearing electron‐withdrawing and electron‐donating substituents was successfully converted to the corresponding pyrazole derivatives. The method was scalable under batch conditions, demonstrating its practical applicability. In addition, the ester group present in the products could be transformed into the corresponding carboxylic acid and amide derivatives, providing access to structurally diverse pyrazole scaffolds. The protocol was also translated to continuous‐flow conditions, offering an efficient and sustainable route to these valuable heterocyclic compounds.