Design, synthesis and cytotoxicity of nitrogen-containing tanshinone derivatives

Tanshinones were used as starting material to synthesize a small library of nitrogen heterocyclic derivatives featured with oxazole, imidazole, and pyrazine ring between C-11/C-12 by simple methods. Except for salviamine A and isosalviamine A, 22 new derivatives were synthesized. Their structures were confirmed by spectroscopic analysis. Moreover, 11 derivatives exhibited moderate cytotoxic activities against five human cancer lines in vitro.