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 (2,7,9-triacetyloxy-5-hydroxy-4,8,12,18-tetramethyl-17-oxo-13,16,19-trioxapentacyclo[13.4.0.01,18.03,8.012,14]nonadecan-10-yl) butanoate .
user
C30H42O13
assistant