氨气

3-oxo-2-(3-oxo-3H-isobenzofuran-1-ylidene)-butyric acid ethyl ester

Propanedioic acid, 2-(3-oxo-1(3H)-isobenzofuranylidene)-, 1,3-diethyl ester

ethyl 2-cyano-2-(3-oxo-2-benzofuran-1-ylidene)acetate