You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (6-methyl-4-oxopyrido[1,2-a]pyrimidin-2-yl)methyl 3-[(3aR,7aR)-1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl]propanoate .
user
C21H23N3O5
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