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 (3aR,7aS)-2-[2-(3,4-dimethoxyphenyl)ethyl]-5,6-dimethyl-3a,4,7,7a-tetrahydroisoindole-1,3-dione .
user
C20H25NO4
assistant