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 N-benzyl-N-[(5,6-dimethyl-4-oxo-3H-thieno[2,3-d]pyrimidin-2-yl)methyl]cyclobutanecarboxamide .
user
C21H23N3O2S
assistant