You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule [(7S,8R)-7-[(E)-2-methylbut-2-enoyl]oxy-7,8-dihydro-3H-pyrrolizin-1-yl]methyl (2R)-2,3-dihydroxy-2-[(1S)-1-methoxyethyl]-3-methylbutanoate into molecular formula.
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C21H31NO7
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