6-phenyl-1,3-diazinane-2,4-dione

6-phenyl-2-sulfanylidene-1,3-diazinan-4-one

5-[(2,4-dinitrophenyl)methylidene]-2,2-dimethyl-1,3-dioxane-4,6-dione

2,2-dimethyl-5-propanoyl-1,3-dioxane-4,6-dione

3,3-dimethyl-9,9-dioxo-2,4-dioxa-9λ⁶-thiaspiro[5.5]undecane-1,5-dione