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-[4-(2-methylpropanoylamino)phenyl]-2-oxoethyl] 7-methylimidazo[1,2-a]pyridine-2-carboxylate .
user
C21H21N3O4
assistant