3-Cyclohexyl-7-methyl-2,4-dioxo-1,2,3,4-tetrahydro-pyrido[2,3-d]pyrimidine-5-carboxylic acid ethyl ester

3,7-Dimethyl-2-methylsulfanyl-4-oxo-3,4-dihydro-pyrido[2,3-d]pyrimidine-5-carboxylic acid ethyl ester

6-methyl-2-oxo-1,2-dihydro-pyridine-3,4-dicarboxylic acid diethyl ester