You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named ethyl (3S)-3-[[2-(8-chloro-1-oxo-7-piperazin-1-yl-3,4-dihydroisoquinolin-2-yl)acetyl]amino]pent-4-ynoate by IUPAC nomenclature, provide its molecular formula.
user
C22H27ClN4O4
assistant