for the following products
(2S)-(1-Tetrahydropyramid-2-one)-3-methylbutanoic acid | (S)-3-Methyl-2-(2-oxotetrahydropyrimidin-1(2H)-yl)butanoic acid | (S)-Tetrahydro-alpha-(1-methylethyl)-2-oxo-1(2H)-pyrimidine acetic acid and 2S-(1-Tetrahydro-pyrimid-2-only)-3-methyl butanoic acid
