A Two-Step Synthesis of Unsymmetrical 1,4-Disubstituted Carbazoles from Sulfonylindoles Under Heterogeneous Catalysis

Reaction of sulfonylindoles with protected beta-nitro ketones affords the corresponding 3-(2-nitroalkyl) indoles that, under acidic conditions, undergo a sequence of cascade processes finally leading to unsymmetrical 1,4-disubstituted carbazoles.