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-methylpropyl (2S)-3-[[(2R)-1-ethoxycarbonylsulfanylbut-3-en-2-yl]carbamoylamino]-2-[(2-methylpropan-2-yl)oxycarbonylamino]propanoate .
user
C20H35N3O7S
assistant