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 N-(2,6-dimethylphenyl)-5-methyl-4-oxo-3-[[(2R)-oxolan-2-yl]methyl]thieno[2,3-d]pyrimidine-6-carboxamide .
user
C21H23N3O3S
assistant