(4S,4a'S,8a'S)-2'-(1,3-dioxolan-2-yl)-4'a,5',6',7',8',8'a-hexahydro-5',5',8a'-trimethylspiro<1,3-dioxolane-4,1'(4'H)-naphthalene>-2-one

(5S,5aS,9aS,9bS)-5-(tert-butyldimethylsilyloxy)-5,5a,6,7,8,9,9a,9b-octahydro-9b-hydroxy-6,6,9a-trimethylnaphtho<1,2-c>furan-3(1H)-one

methyl (4S,4a'S,8a'S)-4'a,5',6',7',8',8'a-hexahydro-5',5',8'a-trimethyl-2,2'-dioxospiro<1,3-dioxolane-4,1'(4'H)-naphthalene>-2'-carboxylate

methyl (4S,4'S,4a'S,8a'S)-4'-(tert-butyldimethylsilyloxy)-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