Enantioselective Total Synthesis of (-)-Zygadenine.

The alkaloids are highly complex steroidal alkaloids characterized by their intricate structural and stereochemical features and exhibit a diverse range of pharmacological activities. A new synthetic pathway has been developed to access this family of natural products, which enabled the first total synthesis of (-)-zygadenine. This synthetic route entails the construction of a hexacyclic carbon skeleton through a stereoselective intramolecular Diels-Alder reaction, followed by a radical cyclization. Subsequently, a meticulously designed sequence of redox manipulations was optimized to achieve the synthesis of this highly oxidized alkaloid.