1,5,6,7-四氢环戊并[d]嘧啶-4-酮

methyl 2-oxo-1-(3-oxobutyl)cyclopentane-1-carboxylate

1-甲基-2-氧代环戊烷羧酸甲酯

甲醇

2-(oxomethylidene)cyclopentan-1-one