(1aR,1bR,5aR,6aR)-5a-methylhexahydrospiro[indeno[1,2-b]oxirene-3,2'-[1,3]dioxolan]-6(2H)-one

(3S,3aR,7aS)-7a-methyl-3,3a,4,6,7,7a-hexahydrospiro[indene-5,2'-[1,3]dioxolan]-3-ol

(1aR,1bS,5aR,6S,6aS)-1b-methyloctahydro-1H-spiro[cyclopropa[a]indene-4,2'-[1,3]dioxolan]-6-ol