3-oxo-2-(2-oxo-propyl)-pentanoic acid ethyl ester

ethyl 2,3-dimethylbut-2-enoate

2,3-dimethyl-2-butene-1-ol

2-(Methylthiomethylene)-pent-2-en-3-one

4-(Methylthiomethylene)-hepta-2,5-dione