You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(2S,8R)-8-[(4-bromophenyl)methyl]-6-(3,5-dichlorophenyl)-7-methoxy-5-oxo-2,3-dihydro-1H-pyrrolizin-2-yl]acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C23H21BrCl2N2O3
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