Methyl 14, 15-dinor-13-oxo-7-labden-15-oate was obtained from acid zamoranic acid methyl ester. The former by photochemical cleavage yielded methyl 7, 9 (11)-drimadien-12-oate, whose chemoselective epoxidation afforded methyl 9α, 11-epoxy-7-drimen-12-oate, which is the key synthetic precursor for pereniporin B, polygodial and warbuganal.
![methyl (4S,4a'S,8a'S)-4'a,5',6',7',8',8'a-hexahydro-5',5',8'a-trimethyl-2-oxospiro[1,3-dioxolane-4,1'(4'H)-naphthalene]-2'-carboxylate Structure](https://image.chemsrc.com/caspic/151/121617-62-7.png)