ethyl 7-oxohept-2-enoate

1,3-dithian-2-spiro-1'-(2'-ethoxycarbonylmethyl)cyclopentane

Acetic acid, 2-(2-oxocyclopentylidene)-, ethyl ester

ethyl 2-hydroxy-2-(2-oxocyclopentyl)acetate

环戊酮