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 4,7-dichloro-3-hydroxy-3-(2-oxopropyl)-1-[(5-phenyl-1,3,4-oxadiazol-2-yl)methyl]indol-2-one .
user
C20H15Cl2N3O4
assistant