5-nitroindole-2,3-dicarboxylate as the major product. In a similar manner, the dimethyl 1-benzyl- and 1-benzenesulfonylindole-2,3-dicarboxylates provided a mixture of the corresponding 4-nitro-, 5-nitro-, 6-nitro- and 7-nitroindole derivatives. However, dimethyl 5-bromoindole-2,3- dicarboxylate gave dimethyl 5-bromo-4-nitroindole-2,3-dicarboxylate as the sole product, which was converted to dimethyl 4-aminoindole-2