You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 1-(7-methyl-2-phenyl-[1,3]oxazolo[5,4-d]pyrimidin-5-yl)piperidine-3-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H22N4O3
assistant