You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4-nitrophenyl)methyl (5R)-6-[acetyloxy-(3,9,9-trimethyl-3,4-diazatricyclo[6.1.1.02,6]deca-2(6),4-dien-5-yl)methyl]-6-bromo-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C27H27BrN4O7S
assistant