Total Synthesis of Liangshanone

Abstract The first total synthesis of liangshanone, a hexacyclic ent ‐kaurane diterpenoid alkaloid, has been completed. Its intricate cagelike framework was assembled through several key transformations, including an oxidative dearomatization/Diels–Alder (OD/DA) cycloaddition sequence, a tandem alkene cleavage/Mannich cyclization, a Robinson‐type annulation, and an intramolecular aldol reaction. Notably, an organocatalytic enantioselective α‐hydroxymethylation process allowed the preparation of an enantiomerically enriched tricyclic intermediate that should enable asymmetric access to the target natural product.