You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 1-[4-[2-[[(6S)-2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazin-6-yl]oxymethyl]phenyl]phenyl]ethanone .
user
C21H19N3O5
assistant