* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
General procedure: The 4,4'-dihalo-2-nitrobiphenyl (0.004 mol) and 4-nitrotoluene (0.006 mol) were heated at 160 °C with an excess of trialkyl phosphite (0.05 mol) under argon for 5 h (a-h, j, k) or 17 h (i, m). After cooling the excess of trialkyl phosphite and the trialkyl phosphate were removed under vacuum. The reaction mixture was chromatographed (column 3.x.60 cm) on silica gel in toluene/heptane (1:1 by vol). The main product 7 (Rf=0.8-0.9) was easy separated from the side product 8 (Rf=0.5-0.6). The prepared new materials (7a-m) were characterized by TLC, elemental analysis, melting point, 1H and 13C NMR and FTIR. The chromatographic pure materials 7 were for melting point determination recrystallized from methanol. The non-alkylated carbazoles 8 were identified by means of separately prepared 2,7-diiodocarbazole10 (8a-c), 2,7-dibromocarbazole8 (8d-f), 2,7-dichlorocarbazole7 (8g-i), and with commercial carbazole11 (8j-m).