You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(3aS,6aS)-3-(4-bromo-2-chlorophenyl)-5,5-dioxo-3a,4,6,6a-tetrahydrothieno[3,4-d][1,3]thiazol-2-ylidene]-2-(3,4-dimethoxyphenyl)acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H20BrClN2O5S2
assistant