You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 2-[2-[(2S)-2-ethylpiperidin-1-yl]-2-oxoethyl]sulfanyl-3-(furan-2-ylmethyl)-6-methyl-5H-pyrrolo[3,2-d]pyrimidin-4-one .
user
C21H26N4O3S
assistant