4-chloro-2-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidine

methyl 3-bromo-2-oxocyclopentane-1-carboxylate

9-methylidenespiro[4.4]nonan-4-one

甲基7-(5-氧代-1-环戊烯-1-基)庚酸酯

2-(hydroxymethyl)cyclopentan-1-one