Total Synthesis of Ritterazine B

The first total synthesis of the cytotoxic alkaloid ritterazine B is reported. The synthesis features a unified approach to both steroid subunits, employing a titanium-mediated propargylation reaction to achieve divergence from a common precursor. Other key steps include gold-catalyzed cycloisomerizations that install both spiroketals and late stage C-H oxidation to incorporate the C7' alcohol.

Automated summary

The first total synthesis of the cytotoxic alkaloid ritterazine B was achieved using a unified approach to synthesize both steroid subunits, employing a titanium-mediated propargylation reaction and gold-catalyzed cycloisomerizations. Key steps also included late stage C-H oxidation to incorporate the C7' alcohol.