[{"from": "human", "value": "Use the given information to create a molecule that fulfills the desired purpose. The molecule is a 2-oxo monocarboxylic acid anion that is the conjugate base of 2-oxopentanoic acid, obtained by deprotonation of the carboxy group. It is a 2-oxo monocarboxylic acid anion and a member of oxopentanoates. It is functionally related to a valerate. It is a conjugate base of a 2-oxopentanoic acid."}, {"from": "gpt", "value": "[C][C][C][C][=Branch1][C][=O][C][=Branch1][C][=O][O-1]"}]