You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 1-[(4aS,8R)-8-pyrrolidin-1-yl-2,3,4,4a,5,7,8,8a-octahydropyrano[3,4-b]pyrazin-1-yl]-2-(3,4-dimethylphenyl)ethanone .
user
C21H31N3O2
assistant