You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(3R)-3-[[(2S)-2-amino-3-methylbutanoyl]oxymethyl]-4-(2-aminopurin-9-yl)butyl] octadec-9-enoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C33H56N6O4
assistant