Retro-[4+2]/Intramolecular Diels–Alder Cascade Allows a Concise Total Synthesis of Lucidumone

Lucidumone is a recently isolated meroterpenoid displaying interesting biological activity. This natural product possesses a complex structure, including a bicyclo[2.2.2]octane possessing 6 contiguous stereogenic centers. Herein, we discuss strategies to solve this synthetic challenge. In particular, we developed a new method for the inverse electron-demand Diels–Alder cycloaddition between 2-pyrones and acyclic enol ethers, as a mean to obtain a ‘masked’ cyclohexadiene. This method allowed an expeditious enantioselective synthesis of (+)-lucidumone through a retro-[4+2]/intramolecular Diels–Alder reaction cascade. 1 Introduction 2 Retrosynthetic Considerations on the Bicyclo[2.2.2]octane 3 Development of a Methodology for Enantioselective IEDDA Cycloadditions 4 Enantioselective Total Synthesis of (+)-Lucidumone 5 Conclusion