You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named methyl 4-[(4R)-3-methyl-5-oxo-6,7,8,9-tetrahydro-4H-[1,2]oxazolo[5,4-b]quinolin-4-yl]benzoate by IUPAC nomenclature, provide its molecular formula.
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C19H18N2O4
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