You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name (3S,3aR,9S,9aS)-3a,6,6-trimethyl-3-nitro-1,1-dioxo-9-phenyl-2,3,5,7,9,9a-hexahydrothieno[3,2-b]chromen-8-one ?
user
C20H23NO6S
assistant