You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named ethyl (3aS,6aS)-6a-(4-chlorophenyl)-5-(2-methoxyphenyl)-4,6-dioxo-1,3a-dihydropyrrolo[3,4-c]pyrazole-3-carboxylate is given. What is its corresponding molecular formula?
user
C21H18ClN3O5
assistant