2-diazonio-1-(4-methoxycarbonylpyridin-3-yl)ethenolate

pyrano[4,3-c]pyridine-1,4-dione

呋喃并[3,4-c]吡啶-3(1H)-酮

4-(3',5'-二甲氧基-4'-羧基苯氧基甲基)烟酸二甲酯