Enantioseparation and antioxidant activity of novel diarylpyrazoline derivatives

Three chiral pyrazoline derivatives were synthesized by a flavanone ring‐opening reaction followed by cyclocondensation with hydrazine hydrate to give better yields. Their enantiomeric resolution was achieved using polysaccharide chiral stationary phase columns consisting of cellulose (Chiralcel®OD‐RH, Chiralcel®OZ‐3) and amylose (Chiralpak®IA) by high‐performance liquid chromatography. The separation was affected by the nature and concentration of the alcohol modifiers in the mobile phase. Taking 5‐methoxy‐2‐(3‐phenyl‐4,5‐dihydro‐1H‐pyrazol‐5‐yl)phenol (3a) as an example, the best separation was obtained by using the Chiralpak®IA column, with a separation factor α = 1.24 and Rs = 5.66 within an analysis time of