Synthesis of an ent ‐Kaurane Intermediate En Route to Grayanane Diterpenes: A Solution to the C‐D Ring Diol Motif

Herein, we report a strategy for accessing the C‐D ring diol motif common in grayanane diterpenes. It provides four generations of synthetic efforts, featuring two attempted directed C─H oxidation strategies toward the C‐D ring and the gradual evolution of the last two strategies (both based on a key Wagner–Meerwein rearrangement). These culminate in the solution of the C‐D ring oxidation states, which are common in most grayanane diterpenes. This work was performed on ent ‐kaurane and ent ‐beyerane scaffolds, and the target diol motif is prepared in moderate yield (23% over 8 steps). The approach is scalable and provides a strategic starting point for these promising antipain agents and entry into grayanane diterpenes.