You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R,4R)-4-hydroxy-3-[(3-methoxyphenyl)methyl]-1-(6-methylpyridine-2-carbonyl)piperidine-3-carboxylic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H24N2O5
assistant