You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule (1S,4R,8R)-9-[2-(4-methylsulfonylphenyl)acetyl]-4-propan-2-yl-2-oxa-5,9-diazatricyclo[6.3.0.01,5]undecan-6-one ?
user
C20H26N2O5S
assistant