You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (3,3-dimethyl-2-oxobutyl) 3-[(3aR,7aR)-1,3-dioxo-3a,4,7,7a-tetrahydroisoindol-2-yl]benzoate by IUPAC nomenclature, provide its molecular formula.
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C21H23NO5
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