PEG-mediated synthesis, antibacterial, antifungal and antioxidant studies of some new 1,3,5-trisubstituted 2-pyrazolines

A new series of 1,3,5-trisubstituted 2-pyrazoline derivatives (3a-l) are synthesized in good to excellent yields from the corresponding chalcones (1a-h) and acid hydrazides (2a-e) in polyethylene glycol-400 (PEG-400) as a green reaction medium. The newly synthesized 2-pyrazoline derivatives are screened for their antibacterial and antifungal activity. The synthesized trisubstituted pyrazolines displayed moderate to good antibacterial and antifungal properties as compared with the standard reference penicillin and fluconazole drugs. Additionally, the antioxidant potential of the 1,3,5-trisubstituted 2-pyrazolines is evaluated by OH and DPPH assay. The 1,3,5-trisubstituted 2-pyrazolines showed good radical scavenger activity and were found as good antioxidant agents.

Synthesis of Trifluoromethylated Pyrazolidines, Pyrazolines and Pyrazoles via Divergent Reaction of β-CF3-1,3-Enynes with Hydrazines

Three types of trifluoromethylated pyrazolidines, pyrazolines, and pyrazoles can be synthesized via divergent reaction of β-CF₃-1, 3-enyne with hydrazines. The reaction with simple hydrazine monohydrate or sulfonyl hydrazines as nucleophiles produces 1,3,4-trisubstituted pyrazolines, whereas the reaction with acetyl hydrazine as nucleophiles affords 1,4,5-trisubstituted pyrazolidines. Using phenylhydrazine or tert-butylhydrazine as a reaction partner, the products are easily oxidized to form 1,4,5-trisubstituted pyrazoles.