You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(1S)-2-(dimethylamino)-2-oxo-1-phenylethyl] 3-(3-oxo-1,4-benzoxazin-4-yl)propanoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H22N2O5
assistant