[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule is an optically active form of vernolic acid having (12R,13S)-configuration. It is an enantiomer of a (+)-vernolic acid."}, {"from": "gpt", "value": "[C][C][C][C][C][C@H1][C@H1][Branch1][Ring2][O][Ring1][Ring1][C][/C][=C][\\C][C][C][C][C][C][C][C][=Branch1][C][=O][O]"}]