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