A Global and Local Desymmetrization Approach to the Synthesis of Steroidal Alkaloids: Stereocontrolled Total Synthesis of Paspaline

A stereocontrolled total synthesis of the indole diterpenoid natural product paspaline is described. Key steps include a highly diastereoselective enzymatic desymmetrization, substrate-directed epoxidation, Ireland-Claisen rearrangement, and diastereotopic group selective C-H acetoxylation to assemble the target with excellent stereofidelity. The route and results described herein outline complementary conceptual disconnections in the arena of steroid natural product synthesis.