You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Name the molecular formula for the molecule established as 2-methylsulfanyl-6-oxo-4-(1-propan-2-yl-3,4-dihydro-2H-quinolin-6-yl)-1H-pyrimidine-5-carbonitrile using the IUPAC nomenclature.
user
C18H20N4OS
assistant