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 (6R,7S)-6,7,9,10-tetrahydroxy-7-methyl-2-(4-methylpiperidin-1-yl)-6,8-dihydro-5H-anthracene-1,4-dione .
user
C21H25NO6
assistant