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,3'S,4'S,5R,7R,10S,13R,15S,17R,18R,21R)-7-hydroxy-1,3',4',6,6,10,17,21-octamethylspiro[14-oxapentacyclo[11.7.1.02,11.05,10.018,21]henicos-2(11)-ene-15,5'-oxolane]-2'-one .
user
C31H48O4
assistant