Robust Organocatalytic Three-Component Approach to 1,3-Diarylallylidene Pyrazolones via Consecutive Double Condensation Reactions.

A robust pyrrolidine-BzOH salt-catalyzed one-pot three-component reaction involving 4-unsubstituted pyrazolones, aryl/heteroarylaldehydes, and aryl methyl ketones is reported for the first time. This catalytic process fortifies an efficient method, allowing for the practical synthesis of a wide array of synthetically useful 1,3-diarylallylidene pyrazolones in good to high yields exclusively in their single geometrical isomer forms. Furthermore, this catalyst facilitates a sequential double condensation reaction under thermal conditions, thereby enabling two consecutive C═C bonds through displacement of aryl groups. Moreover, this organocatalytic technique achieves a 100% carbon atom economy, marking a significant step forward toward efficient and sustainable synthesis.