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 7-[3-chloro-4-[(2R)-2-methylpiperazin-1-yl]anilino]-3-(2,6-dichlorophenyl)-2H-pyrimido[5,4-e][1,3]oxazin-4-one is given. What is its corresponding molecular formula?
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C23H21Cl3N6O2
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