You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name 2-[2-(2,3,4a,5,6,7,8,8a-octahydrobenzo[b][1,4]oxazin-4-yl)-2-oxoethyl]sulfanyl-3,5,6-trimethylthieno[2,3-d]pyrimidin-4-one ?
user
C19H25N3O3S2
assistant