You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3R,6R)-3-[2-(4-chloro-2-ethyl-1H-indol-3-yl)ethyl]-6-(pyridin-2-ylmethyl)piperazine-2,5-dione by IUPAC nomenclature, provide its molecular formula.
user
C22H23ClN4O2
assistant