You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4-chloro-2-methylphenyl) 7a-methyl-5-oxo-2,3,6,7-tetrahydropyrrolo[2,1-b][1,3]thiazole-3-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C15H16ClNO3S
assistant