4-oxononanedioic acid

3-(6-oxocyclohexen-1-yl)propanoic acid

(4aS,8aS)-3,4,5,6,7,8-hexahydro-2H-spiro[8a,4a-(epoxymethano)chromene-10,1'-cyclohexa[2,5]diene]-2,4'-dione

8a-(4-hydroxyphenoxy)-3,5,6,7,8,8a-hexahydro-2H-chromen-2-one

methyl 3-(6-oxocyclohexen-1-yl)propanoate