5-(1-hydroxy-3-oxobutylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione

2-溴-3-氧代丁酸乙酯

(1-benzylpiperidin-3-yl) 3-oxobutanoate

(2,2-dimethyl-1,3-dioxolan-4-yl)methyl 3-oxobutanoate

1-(10-methyl-1-oxa-5-azaspiro[5.5]undecan-5-yl)butane-1,3-dione