butenolideβ-angelica lactone2-Furanoneγ-crotonolactonefuran-2-one2,5-dihydrofuran-2-one2-Buten-1,4-olide , gamma-CrotonolactoneFuran-2(5H)-oneγ-巴豆酰内酯2-Buten-1,4-olide2(5H)-呋喃酮2(5H)-呋喃酮2(5H)-Furanone2(5H)-Furanoneγ-巴豆酰内酯γ-Crotonolactonegamma-Crotonolactonebut-2-en-4-olidegamma-hydroxycrotonic acid lactoneButenolide2-buten-4-olide2-oxo-2,5-dihydrofuran4-hydroxy-2-butenoic acid lactonealpha,beta-crotonolactonegamma-crotonolactone2-butenolidebutenolide2(5H)-furanonegamma-Crotonolactone