3,3A,6,6A-四氢-2H-环戊二烯并[b]呋喃-2-酮

benzyl 2-(4-oxocyclopent-2-en-1-yl)acetate

(3aS,6aS)-tetrahydro-2H-cyclopenta[b]furan-2,5(3H)-dione

methyl 2-(6-oxo-2,4,5,6-tetrahydrocyclopenta[c]pyrrol-4-yl)acetate

benzyl 2-(6-oxo-2,4,5,6-tetrahydrocyclopenta[c]pyrrol-4-yl)-acetate