Synthesis and Biological Evaluation of New (−)-Gossypol-Derived Schiff Bases and Hydrazones

Scheme 3

Synthesis of hydrazones 12a–e; (i) MeOH, H₂SO₄, MeOH, reflux, 12 h; (ii) EtOH, NH₂NH₂ (80%), r.t, 10 h; (iii) EtOH, ZnCl₂, r.t, 12 h, 48.7–53.0%.