A novel pseudo six-component synthesis of functionalized pyrazoles in ethanol by cascade reaction.

Novel-substituted pyrazoles were synthesized using an aminal-based approach. The key steps in the synthetic strategy involve the formation of 1,1-dihydrazino-2-nitroethylene from hydrazine hydrate with nitro ketene dithioacetal and its reaction with Knoevenagel adduct derived from the corresponding aldehyde and malononitrile in ethanol media. The formation of 5-membered pyrazole ring is confirmed based on the electrostatic surface potential computed by density functional theory.