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 methyl 2-[(7-methyl-1-oxo-3,4-dihydroisochromene-3-carbonyl)amino]-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate .
user
C21H21NO5S
assistant