You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2S,4S,5R)-8,9-diethyl-2,4-diphenyl-1,3-dioxaspiro[4.4]non-8-en-7-one by IUPAC nomenclature, provide its molecular formula.
user
C23H24O3
assistant