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 tert-butyl 4-[6-(azetidine-1-carbonyl)-2,3,6,7-tetrahydrothieno[3,2-b][1,4]oxazin-4-yl]benzoate is given. What is its corresponding molecular formula?
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C21H26N2O4S
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