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,7S)-13-(2-fluoro-4-methoxyphenyl)-4,8-diazatetracyclo[6.6.1.02,7.011,15]pentadeca-1(14),11(15),12-triene .
user
C20H21FN2O
assistant