D-ring substituted rhazinilam analogues: semisynthesis and evaluation of antitubulin activity.

Novel (-)- and (+)-rhazinilam derivatives substituted on the D-ring (compounds 3, 4, 5 and 6) have been prepared from (+)-vincadifformine 7 and (-)-tabersonine and evaluated against the disassembly of microtubules into tubulin. Along with this study, a reproducible 'one pot' semisynthesis of (-)-rhazinilam 1 from (+)-1,2-didehydroaspidospermidine 2 was performed allowing the easy preparation of these new compounds.