反应详情

Following the procedure of Example 9, 5 g. of 3,4-dibromo-6-nitroaniline were reduced in anhydrous ethanol with Raney nickel to yield 4,5-dibromo-o-phenylenediamine which was not isolated but mixed immediately with 2.47 g. of 2-ketoglutaric acid. One hundred ml. of ethanol were added and the mixture heated to refluxing temperature for 3 hours. 3 gms. of β-(6,7-dibromo-3,4-dihydro-3-oxo-2-quinoxaline)propionic acid were obtained melting at 249°-250° C. The free acid was converted to the corresponding ethyl ester by the procedure of Example 8. Ethyl β-(6,7-dibromo-3,4-dihydro-3-oxo-2-quinoxaline)propionate thus prepared melted at 189°-190° C.