[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is a 2-methylbutanedioic acid in which the methyl group at position 2 has R-configuration. It is an enantiomer of a (S)-methylsuccinic acid."}, {"from": "gpt", "value": "[C][C@H1][Branch1][#Branch1][C][C][=Branch1][C][=O][O][C][=Branch1][C][=O][O]"}]