You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (1S,4aR,5S,8aR)-5-[2-[(2R)-2-hydroxy-5-oxo-2H-furan-4-yl]ethyl]-1,4a-dimethyl-6-methylidene-3,4,5,7,8,8a-hexahydro-2H-naphthalene-1-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H30O5
assistant