You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 5-[4-[9-[4-(1,3-dioxo-2-benzofuran-5-carbonyl)phenyl]fluoren-9-yl]benzoyl]-2-benzofuran-1,3-dione .
user
C43H22O8
assistant