You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 2-[(1S,5S,6R,7R)-6-[[[2-(4-ethylphenyl)acetyl]amino]methyl]-10-oxa-3-azatricyclo[5.2.1.01,5]decan-3-yl]acetic acid .
user
C21H28N2O4
assistant