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 2-[4-(4-methyl-6,7-dihydro-4H-thieno[3,2-c]pyridin-5-yl)butyl]isoindole-1,3-dione .
user
C20H22N2O2S
assistant