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 2,2-dichloro-N-[2-[1-(3-methoxyphenyl)-3,4-dihydro-1H-pyrrolo[1,2-a]pyrazin-2-yl]-2-oxoethyl]-N-propan-2-ylacetamide into molecular formula.
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C21H25Cl2N3O3
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