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 (1S,2S,6R,9R,11S,13S)-9,13-dimethyl-5-methylidene-3-oxatetracyclo[7.4.0.02,6.011,13]tridecan-4-one .
user
C15H20O2
assistant