((1S,4aR,8aS)-1,4a-Dimethyl-2-methylene-5-oxo-decahydro-naphthalen-1-yl)-acetic acid ethyl ester

ethyl 2-((4aS,5R,6S,8aR)-5,6,8a-trimethyloctahydro-2H-spiro[naphthalene-1,2'-[1,3]dioxolan]-5-yl)acetate

ethyl 2-((4aS,5S,8aR)-5,8a-dimethyl-6-methyleneoctahydro-2H-spiro[naphthalene-1,2'-[1,3]dioxolan]-5-yl)acetate