You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (1R,2S,10S,13S)-7,8,18,19-tetramethoxy-6,17,21-trimethyl-12-oxo-5,16-bis(phenylmethoxy)-11,21-diazapentacyclo[11.7.1.02,11.04,9.015,20]henicosa-4(9),5,7,15(20),16,18-hexaene-10-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C43H48N2O9
assistant