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 2-[1-[2-(4-ethylpiperazin-1-yl)acetyl]-3-oxopiperazin-2-yl]-N-(4-methoxyphenyl)acetamide .
user
C21H31N5O4
assistant