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 (4S,9bR)-4-(benzenesulfonyl)-3,6,9-trimethyl-3,3a,4,5,9a,9b-hexahydroazuleno[4,5-b]furan-2,7-dione ?
user
C21H22O5S
assistant