penta-3,4-dienoic acid

(-)-(S)-5-p-toluenesulfonyloxymethyloxol-3-en-2-one

2-(hydroxymethyl)-2H-furan-5-one

5-hydroxy-5-methyl-2(5H)-furanone

(-)-(S)-5-iodomethyloxol-3-en-2-one