You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule methyl (4'bR,8'aS)-4'b-ethylspiro[1,3-dioxolane-2,7'-5,6,8,8a,9,10-hexahydrophenanthrene]-2'-carboxylate;methyl (4'bR,8'aR)-4'b-ethylspiro[1,3-dioxolane-2,7'-5,6,8,8a-tetrahydrophenanthrene]-2'-carboxylate into molecular formula.
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C40H50O8
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