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 (2R,4S)-2-phenyl-9-(5H-pyrrolo[3,2-d]pyrimidin-4-yl)-1-oxa-9-azaspiro[5.5]undecan-4-ol ?
user
C21H24N4O2
assistant