You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by (2S)-12-methoxy-7,7-dimethyl-11-nitro-8-oxapentacyclo[7.4.0.02,4.02,6.04,6]trideca-1(13),9,11-triene ?
user
C15H15NO4
assistant