[{"from": "human", "value": "Generate a molecule based on this description. The molecule is a butan-4-olide having a methylene group at the 3-position and two methyl substituents at the 5-position."}, {"from": "gpt", "value": "[C][C][Branch1][=N][C][C][=Branch1][C][=C][C][=Branch1][C][=O][O][Ring1][#Branch1][C]"}]