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,3'aR,8'aR,8'bS)-6-chloro-2'-(2-chloro-4-nitrophenyl)-7-methylspiro[1H-indole-3,4'-3a,6,7,8,8a,8b-hexahydropyrrolo[3,4-a]pyrrolizine]-1',2,3'-trione .
user
C23H18Cl2N4O5
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