Efficient Synthetic Strategies for Highly Functionalized Pyrazole Including an Amidine Skeleton Based on Trichloroacetamidine, Alkynes, and Hydrazonoyl Chlorides

The synthesis of functionalized pyrazole-4-carboximidamide with appropriate yields through a novel four-component reaction from alkynes, hydrazonoyl chlorides, trichloroacetonitrile, and various anilines is a remarkable achievement in heterocycle chemistry. This strategy offers a direct and efficient route to access different pyrazoles with amidine substitution from readily available starting materials. The use of copper (I) as a catalyst, in DMF solvent, without adding a ligand, and with the help of ultrasonic conditions for 50 min at room temperature highlights the importance of transition metal catalysis in this process. The combination of available starting materials, mild reaction conditions, catalytic systems, and ease of purification procedures contributes to the attractiveness of this method for the synthesis of diverse new substituted pyrazoles, including an amidine skeleton.