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 (1R,2R,7R,8R)-7-(3-chlorophenyl)-10-phenyl-4-thia-6,10-diazatricyclo[6.3.0.02,6]undecane-9,11-dione .
user
C20H17ClN2O2S
assistant