You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule [(7R,8aR)-7-ethoxy-3,4,6,7,8,8a-hexahydro-1H-pyrrolo[1,2-a]pyrazin-2-yl]-pyridin-4-ylmethanone ?
user
C15H21N3O2
assistant