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 (4S,4aS,7S,7aS,12bR)-3-(cyclopropylmethyl)-9-methyl-2,4,4a,5,6,7,7a,13-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-ol ?
user
C21H27NO2
assistant