You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-[1-(2-methoxyphenyl)-3,4-dihydro-1H-pyrrolo[1,2-a]pyrazin-2-yl]-2-oxoethyl]-N-propylpropanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H29N3O3
assistant