2-苄基环戊酮

2-prop-2-enylcyclopentan-1-one

tert-butyl 3-ethylcyclopentene-1-carboxylate

methyl 7-(2-oxocyclopentyl)hept-5-ynoate

1-(7-methoxy-7-oxohept-2-ynyl)-2-oxocyclopentane-1-carboxylic acid