You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by (1R,2S,10R,11S,13R,14S,15R,17R)-13,14-dihydroxy-14-(2-hydroxyacetyl)-2,15-dimethyl-18-oxapentacyclo[8.8.0.01,17.02,7.011,15]octadec-6-en-5-one ?
user
C21H28O6
assistant