You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
butyl (1R,5S,6R,7R)-3-benzhydryl-4-oxo-10-oxa-3-azatricyclo[5.2.1.01,5]dec-8-ene-6-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C26H27NO4
assistant