You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (2R)-6-chloro-N-[[2-(2-methylimidazol-1-yl)phenyl]methyl]-4-methylsulfonyl-2,3-dihydro-1,4-benzoxazine-2-carboxamide into molecular formula.
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C21H21ClN4O4S
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