diethyl 2-(1,2-dimethyl-3-oxocyclohexyl)propanedioate

diethyl 2-(6-oxo-1,2,3,4,5,6a-hexahydropentalen-3a-yl)propanedioate

7-(1,3-dioxolan-2-yl)hept-4-ynoic acid

5-chloropent-4-enoic acid

diethyl 2-buta-2,3-dienylpropanedioate