You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-(4-ethoxyanilino)-2-oxoethyl] (3R)-1-(3-chlorophenyl)-5-oxopyrrolidine-3-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H21ClN2O5
assistant