You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
propyl (1S,5R,6R,7R)-3-[(1S)-1-(4-bromophenyl)ethyl]-4-oxo-10-oxa-3-azatricyclo[5.2.1.01,5]dec-8-ene-6-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H22BrNO4
assistant