You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (2Z,5R)-5-(4-acetyloxyphenyl)-7-methyl-2-(1-methyl-2-oxoindol-3-ylidene)-3-oxo-5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C27H23N3O6S
assistant