You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule tert-butyl (2R)-4,4-difluoro-2-(8-methoxy-4-oxo-3H-[1]benzofuro[3,2-d]pyrimidin-2-yl)pyrrolidine-1-carboxylate ?
user
C20H21F2N3O5
assistant