Versatile Applications of Cyanoacetic Acid in Organic Chemistry: Active Methylene Compound for the Knoevenagel Condensation and Organocatalyst for the Biginelli Reaction

Abstract

The application of cyanoacetic acid as a catalyst for the Biginelli reaction and as an active methylene compound for the Knoevenagel condensation reaction was evaluated. Using cyanoacetic acid as a Bronsted acid catalyst, after a synthetic optimization process, it was possible to synthesize eight dihydropyrimidinones with good yields (80-99%) using ethanol as solvent. It is the first time, to our knowledge, that the use of cyanoacetic acid is reported in the synthesis of this class of compounds, which have a wide bioactive potential. Also, cyanoacetic acid was used as a reagent in the Knoevenagel condensation, through which polyfunctionalized olefins were obtained and can be used as building blocks for structurally complex molecules. By using KOH as catalyst, eleven Knoevenagel adducts were synthesized with good yields (65-97%), under microwave irradiation as heating source, in water. Moreover, Knoevenagel adducts containing halogenated substituents (F, Cl) showed potential larvicidal activity with lethal concentrations (LC50) of 19.63, 33.84 µg mL-1 and LC90 of 27.46 and 48.16 µg mL-1. This study showed the versatility of cyanoacetic acid as a catalyst for the synthesis of dihydropirimidinones, aldol compounds and presented the first study showing their larvicidal activity against Aedes aegypti.