You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R)-3-ethyl-4-[(2-propan-2-yl-1,3-oxazol-4-yl)methyl]piperazin-2-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H21N3O2
assistant