You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (5S)-5-[(1S)-2-[bis[(2R)-butan-2-yl]amino]-1-hydroxyethyl]-1-[(2-chlorophenyl)methyl]pyrrolidin-2-one .
user
C21H33ClN2O2
assistant