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 3-ethyl-7,7,8a-trimethyl-5-sulfanylidene-6,8-dihydro-3H-[1,3]oxazolo[3,2-c]pyrimidin-2-one .
user
C11H18N2O2S
assistant