You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [(1S,2S,4S,5'R,6R,7S,8R,9S,12S,13R,16S)-5',7,9,13-tetramethylspiro[5-oxapentacyclo[10.8.0.02,9.04,8.013,18]icos-18-ene-6,2'-oxane]-16-yl] 4-[(4-methoxyphenyl)methyl]piperazine-1-carboxylate by IUPAC nomenclature, provide its molecular formula.
user
C40H58N2O5
assistant