You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S,5R,6S)-2-(1-chloroethyl)-5-methyl-6-(4-nitrophenyl)-2,4-diphenyl-5,6-dihydro-1,3-oxazine is the IUPAC name of a molecule. Please give its molecular formula.
user
C25H23ClN2O3
assistant