The first biomimetic synthesis of a diterpenoid with the ent -verrucosin A/B skeleton

The first biomimetic synthesis of methyl (8 S ,9 R ,13 R ,14 R )-4,4,8,9,13-pentamethyl-20(10 → 9)-abeo- ent -isocopal-5(10),11(12)-dien-15-oate—a diterpenoid with the ent -verrucosin A/B skeleton has been performed by electrophilic isomerization of methyl 12α-hydroxy- ent -isocopal-13(16)-en-15-oate. The structure and stereochemistry of the synthesized compound have been established on the basis of spectroscopic data.