You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3S,8aS)-N-(4-chlorophenyl)-3-[2-(methylamino)propanoylamino]-4-oxo-2,3,6,7,8,8a-hexahydropyrrolo[2,1-b][1,3]oxazine-6-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H23ClN4O4
assistant