You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (2R)-2-(butoxycarbonylamino)-3-[[2-[(5S)-3-(4-cyanophenyl)-4,5-dihydro-1,2-oxazol-5-yl]acetyl]amino]propanoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H26N4O6
assistant