A rational synthesis of benzylidene diarylheptanoids: A hybrid of combretastatin A and mono-keto curcumin

Combretastatin A’s (CA1–CA5) are important cis-stilbenoid-type anticancer natural products that suffer from short biological half-life and cis-trans isomerization in vivo. Herein, the synthesis of a novel class of benzylidene diarylheptanoids based on combretastatin A and mono-keto curcumin is demonstrated. Where the cis-form of combretastatin A is locked to mono-keto curcumin. Aldol condensation of combretastatin aldehyde with a ketone (acetone/cyclopentanone/cyclohexanone/N-methyl-4-piperidone) in the presence of a base (LiOH/Ba(OH)₂) affords target compounds in 36–70% yield. Target compounds and their precursors, combretastatin aldehydes, were completely characterized by spectroscopic methods and single-crystal XRD studies. Our efforts offer natural products (combretastatin A and mono-keto curcumin), based novel and isomerically stable benzylidene diarylheptanoids of great potential for cancer chemotherapy.