Preparation of precursors for the synthesis of analogues of rhazinilam

Rhazinilam a structurally relatively simple tetracyclic natural product exerts interesting anticancer activities in vitro, which are difficult to reproduce in vivo. Based on the findings accumulated during the synthetic efforts and on the known metabolic sensitivity towards oxidation and acids a modified structural analogue of rhazinilam is proposed. A novel convergent approach towards the heterocyclic biaryl unit is described. The key sequence for the construction of 7 is the Mukaiyama crossed aldol reaction followed by the Staudinger reaction. Using known N-alkylation procedures the introduction of the side chains onto the 3-pyrrolin-2one intermediate 2 needed for the construction of the tetracycle could not be achieved.