2,3,4-trimethyl-1,2-oxazol-5-one

diethyl 2-acetyl-4-ethylidene-2-methylpentanedioate

diethyl 2-acetyl-2,3-dimethyl-4-methylidenepentanedioate

2-Acetyl-4-eth-(Z)-ylidene-2-methyl-pentanedioic acid diethyl ester

ethyl (2S)-2-acetyl-2-methyl-5-oxohexanoate