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 1-(4-chlorophenyl)-3-cyano-2-[(2R,3S,4R)-2-(dimethoxymethyl)-3-hydroxy-2-methyl-6-nitro-3,4-dihydrochromen-4-yl]guanidine .
user
C21H22ClN5O6
assistant