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 (2R,6R,7S)-4-(3-bromophenyl)-7-(4-methoxyphenyl)-1,4,8-triazatricyclo[6.3.0.02,6]undecane-3,5-dione .
user
C21H20BrN3O3
assistant