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 (E)-N-butyl-N-(1,1-dioxothiolan-3-yl)-3-[4-(2-oxopyrrolidin-1-yl)phenyl]prop-2-enamide .
user
C21H28N2O4S
assistant