Domino Synthesis of Bis Phenyl Pyrazolone Piperidinium Salt Derivatives

Abstract The synthesis of bis phenyl pyrazolone piperidinium salt derivatives from the reaction between an aromatic aldehyde, 3‐methyl‐5‐phenyl pyrazolone and piperidine in ethanol is described here. The reaction seemed to proceed via Knoevenagel condensation followed by hydrogen bond formation to give the organic salt as the sole product. Piperidine acted as both, the reactant and the catalyst. The products were formed in good yields for different aldehydes containing electron withdrawing and electron donating groups. The reaction proceeded in mild conditions, in short reaction time and the products were isolated without the use of column chromatography. The products were confirmed by spectroscopic techniques such as FT‐IR, 1 H, 13 C & DEPT 135‐NMR and HR‐MS.