You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 6-[2-[(2,5-dimethoxyphenyl)methylamino]-2-oxoethyl]thieno[2,3-b]pyrrole-5-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H22N2O5S
assistant