You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Name the molecular formula for the molecule established as (1R,2S,5S,8R,9R,10S,11S,13R,18R)-9,10,13,18-tetrahydroxy-12,12-dimethyl-6-methylidene-17-oxapentacyclo[7.6.2.15,8.01,11.02,8]octadecan-7-one using the IUPAC nomenclature.
user
C20H28O6
assistant