5-hydroxy-4-oxohexanoic acid

3-oxo-1,2,5,6,11,11b-hexahydroindolizino[8,7-b]indole-5-carboxylic acid

2,2-bis(trifluoromethyl)-1,3,6-trioxaspiro[4.4]nonane-4,7-dione

dibutyl 2-oxopentanedioate

dipropan-2-yl 2-oxopentanedioate