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 1-[(4R,7R,8aS)-4-(3-morpholin-4-yl-3-oxopropyl)-1-oxo-3,4,6,7,8,8a-hexahydro-2H-pyrrolo[1,2-a]pyrazin-7-yl]-3-(furan-2-ylmethyl)thiourea ?
user
C20H29N5O4S
assistant