Polymerisation of indole. Part 3. Two indolylquinolines, an indole tetramer, and the dihydro derivative of the indole dimer

Abstract

Treatment of indole (1) with toluene-p-sulphonic acid in Dowtherm A gave the dihydro dimer (7), the indol-3-ylquinoline (8), the indol-2-ylquinoline (10), and the tetramer (19). The indol-3-ylquinoline (8) was also produced on treatment of the 2, 3′-trimer (3) with zinc chloride in acetic acid or with toluene-p-sulphonic acid in Dowtherm A. The identification of these products (7), (8), (10), and (19) is described and the mechanisms of formation are discussed.