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 benzyl (3R,6R,12S)-6-[2-[benzyl(2-hydroxyethyl)amino]-2-oxoethyl]-12-(9H-fluoren-9-ylmethoxycarbonylamino)-5,13-dioxo-1-oxa-4-azacyclotridec-8-ene-3-carboxylate .
user
C45H47N3O9
assistant