You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (1'R,2S,5'R)-3-(4-methoxyphenyl)spiro[1H-quinazoline-2,7'-bicyclo[3.2.0]hept-2-ene]-4-one .
user
C21H20N2O2
assistant