You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance tert-butyl-[2-[7-(3,4-difluorophenyl)-6-iodo-1-oxo-3,4-dihydro-2H-pyrrolo[1,2-a]pyrazin-4-yl]ethyl]carbamic acid .
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C20H22F2IN3O3
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