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 [2-[2-[(2R)-butan-2-yl]anilino]-2-oxoethyl] 2,5-dimethyl-4-oxo-3H-thieno[2,3-d]pyrimidine-6-carboxylate .
user
C21H23N3O4S
assistant