螺[1,3-二氧戊环-2,7'-双环[3.2.0]庚-3-烯]

2-(4-oxocyclopent-2-en-1-yl)acetic acid

(3aS,6aR)-1,3a,4,6a-四氢环戊烯并[c]呋喃-3-酮