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 (3R,4S)-3-[(2-aminopyridin-4-yl)methyl]-1-[(3S)-3-phenylbutanoyl]-4-(trifluoromethyl)azetidin-2-one .
user
C20H20F3N3O2
assistant