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 (3R,4R,7aS,12bS)-3-(cyclopropylmethyl)-4a-hydroxy-3-methyl-7-oxo-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-3-ium-9-carboxamide;chloride .
user
C22H27ClN2O4
assistant