methyl 4-oxo-5-phenylsulfanylpentanoate

methyl 4-(2-methylphenyl)-4-oxobutanoate

methyl 4-(4-methylanilino)-4-oxobutanoate

methyl 3-(2-but-3-enyl-1,3-dioxolan-2-yl)prop-2-enoate

methyl 4-[bis(2-methylpropyl)amino]-4-oxobutanoate