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 (2R)-2-[(3aR,7aS)-1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl]-N-(4-chloro-2,5-dimethoxyphenyl)-4-methylsulfanylbutanamide .
user
C21H27ClN2O5S
assistant