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-[2-(4-chlorophenyl)ethyl]-2-methyl-3-[(3-oxo-4H-1,4-benzothiazin-6-yl)sulfonyl]propanamide .
user
C20H21ClN2O4S2
assistant