You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name [(3aR,4S,9bS)-9-(hydroxymethyl)-3-methylidene-2-oxo-3a,4,5,7,8,9b-hexahydrobenzo[g][1]benzofuran-4-yl] (Z)-4-acetyloxy-2-methylbut-2-enoate ?
user
C21H24O7
assistant