Acetic acid (1R,4aS,8aR)-3-isopropylidene-5,8a-dimethyl-4-oxo-1,2,3,4,4a,7,8,8a-octahydro-naphthalen-1-yl ester

(5'R,7'R)-3,3,7',11'-tetramethyl-6',12'-dioxaspiro[oxirane-2,3'-tricyclo[9.1.0.05,7]dodecan]-2'-one