You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(2R)-2-acetyloxy-2-[(2S,3S,5S)-3-(1,3-dioxoisoindol-2-yl)-5-(2,4-dioxopyrimidin-1-yl)oxolan-2-yl]ethyl] acetate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H21N3O9
assistant