Efficient synthesis and cytotoxicity of novel microtubule-stabilizing agent ceratamine A analogues

An efficient synthesis of microtubule-stabilizing agent ceratamine A analogues is described. The key step is the application of either reductive Heck reaction or Heck reaction to construct the imidazo4,5-d]azepine core. Thirteen novel analogues of ceratamine A were synthesized and evaluated for their in vitro cytotoxicity against five human cancer cell lines (HCT-116, HepG2, BGC-823, A549 and A2780). It was the first report about the systematic structural modification and SARs study of ceratamine A. The results demonstrated that bulky substituents at C-14 and C-16 could enhance the cytotoxicy and modification at N-7 was crucial for high potency. Especially compound 1f bearing methyl group at C-14 and C-16, and compound 1k bearing benzyl group on N-7, showed better cytotoxicy than ceratamine A against A549.