Green synthesis and antifungal activities of novel 3‐(trifluoromethyl)‐4, 5‐dihydro‐1 H ‐furo[2,3‐ c ]pyrazole derivatives

Trifluoromethylated molecules, as well as pyrazol‐3‐one derivatives, are found in a wide range of biologically active compounds. An highly facile, green and mild access to substituted 3‐(trifluoromethyl)‐4,5‐dihydro‐1 H ‐furo[2,3‐ c ]pyrazole derivatives by the cascade [3 + 2] Michael/Alkylation of unsaturated pyrazolones with α‐bromomalonate has been developed. The reactions can be performed in a easily available and environmentally benign solvent, and the substituted 3‐(trifluoromethyl)‐4,5‐dihydro‐1 H ‐furo[2,3‐ c ]pyrazole derivatives can be obtained in good to excellent yields by a simple purification step. The antifungal activities of these functional pyrazole derivatives were also evaluated and they showed high antifungal activity against Alternaria solani .