3-propan-2-yloxolane-2,5-dione

2-(2-methoxy-2-oxoethyl)-3-methylbutanoic acid

5,5-二甲基-二氢-呋喃-2-酮

3-isopropyl-5-oxo-hexanoic acid

(2-carboxy-1-isopropyl-cyclopropyl)-acetic acid