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A highly efficient three-component one step system for the synthesis of 2-amino-4H-chromens is developed. Excellent yields were obtained simply by mixing malononitrile, aromatic aldehyde and α-napthol in lemon juice as a catalyst of natural origin and solvent, avoiding using hazardous organic solvents. The main advantages of this method are its green method character, short reaction time and simple workup procedures and the lack of using any metal containing catalysts.

A simple and green one pot protocol for the synthesis of pyranopyrazole using ultrasonication waves in aqueous medium has been developed. An advantages of this method are it provides operational simplicity and environment friendly green approach.

Knoevenagel condensation of pyrazole aldehydes with malononitrile is selectively carried out using ammonium carbonate as mild, cheap, efficient and selective catalyst, in aqueous media at ambient temperature. This method is green and providing expeditious way for Knoevenagel condensation of pyrazole aldehyde.