Asymmetric Total Synthesis of the Indole Diterpene Alkaloid Paspaline

An
enantioselective synthesis of the indole diterpenoid natural
product paspaline is disclosed. Critical to this approach was the
implementation of stereoselective desymmetrization reactions to assemble
key stereocenters of the molecule. The design and execution of these
tactics are described in detail, and a thorough analysis of observed
outcomes is presented, ultimately providing the title compound in
high stereopurity. This synthesis provides a novel template for preparing
key stereocenters in this family of molecules, and the reactions developed
en route to paspaline present a series of new synthetic disconnections
in preparing steroidal natural products.