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 ethyl (4S)-6-[(4-acetamidophenyl)sulfanylmethyl]-4-ethyl-2-oxo-3,4-dihydro-1H-pyrimidine-5-carboxylate .
user
C18H23N3O4S
assistant