[{"from": "human", "value": "Based on the given information, design a molecule that meets the desired specifications. The molecule is a butan-4-olide having a 2-bromoethyl group at the 3-position and two methyl substituents at the 5-position. It is an organobromine compound and a butan-4-olide."}, {"from": "gpt", "value": "[C][C][Branch1][#C][C][C][Branch1][Branch2][C][=Branch1][C][=O][O][Ring1][=Branch1][C][C][Br][C]"}]