You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (1R,2S,4S,8R,9S,12S,13R)-6-(4-hydroxy-3-methylbutyl)-7,9,13-trimethyl-5-oxapentacyclo[10.8.0.02,9.04,8.013,18]icosa-6,17-diene-10,16-dione into molecular formula.
user
C27H38O4
assistant