[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule is a xanthene. It is a tautomer of a 3H-xanthene and a 4aH-xanthene."}, {"from": "gpt", "value": "[C][C][=C][C][=C][C][=C][Ring1][=Branch1][O][C][=C][C][=C][C][=C][Ring1][=Branch1][Ring1][=C]"}]