3-cyano-6-[2]furyl-1-methyl-2-oxo-1,2-dihydro-pyridine-4-carboxylic acid ethyl ester

4ξ-benzoyloxy-2-benzoyloxyimino-4ξ-[2]furyl-but-3-enoic acid ethyl ester

7-furan-2-yl-4-oxo-2-thioxo-1,2,3,4-tetrahydro-pyrido[2,3-d]pyrimidine-5-carboxylic acid