You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (3R,3aS,4S,5R,7aR)-5-[2-chloro-4-(5-methyl-1,3,4-oxadiazol-2-yl)phenyl]-4-(4-chlorophenyl)-7a-ethyl-3-methyl-3,3a,4,5,6,7-hexahydro-2H-isoindol-1-one .
user
C26H27Cl2N3O2
assistant