methyl 7'-hydroxy-2'-methoxy-6',10'-dihydro-7'H,9'H-spiro[[1,3]dioxolane-2,8'-[7,9a]methanobenzo[a]azulene]-1'-carboxylate

methyl 7-hydroxy-2-methoxy-8-oxo-6,8,9,10-tetrahydro-7H-7,9a-methanobenzo[a]azulene-1-carboxylate

2-Hydroxy-7-methoxy-8-(methoxycarbonyl)-1,2,3,4-tetrahydrofluorene-2-carboxylic acid

Dimethyl 2-hydroxy-7-methoxy-1,2,3,4-tetrahydrofluorene-2,8-dicarboxylate