preferred_name: (R)-3-hydroxy-3-methyl-2-oxopentanoate => (S)-2-ethyl-2-hydroxy-3-oxobutanoate
preferred_name_lc: (r)-3-hydroxy-3-methyl-2-oxopentanoate => (s)-2-ethyl-2-hydroxy-3-oxobutanoate
label: (R)-3-hydroxy-3-methyl-2-oxopentanoate => (S)-2-ethyl-2-hydroxy-3-oxobutanoate
label_lc: (r)-3-hydroxy-3-methyl-2-oxopentanoate => (s)-2-ethyl-2-hydroxy-3-oxobutanoate