You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named N-[(3aR,6aR)-3-(2,5-dimethylphenyl)-5,5-dioxo-3a,4,6,6a-tetrahydrothieno[3,4-d][1,3]thiazol-2-ylidene]-2-(4-chlorophenoxy)acetamide is given. What is its corresponding molecular formula?
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C21H21ClN2O4S2
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