You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (1S,2S,4S,5S,7S,8S,9S,11S,13R)-7-propan-2-ylspiro[3,6,10,16-tetraoxaheptacyclo[11.7.0.02,4.02,9.05,7.09,11.014,18]icos-14(18)-ene-8,2'-oxirane]-17-one .
user
C20H22O6
assistant