Synthesis of a trifluoromethylindolocarbazole, novel cyclic 27- and 36-membered N-benzyltri- and -tetraindoles, and an N-benzyltetraindolyltrimethane
5,11-Dihydro-5,11-dibenzyl-6-trifluoromethylindolo[3,2-b]carbazole (6) and the cyclic N-benzylindole trimer 4 were synthesized from both N-benzylindole-3-methanol (1) and N,N'-dibenzyl-3,3'-diindolylmethane (2) by treatment with trifluoroacetic anhydride. The former also gave the 36-membered cyclic N-benzylindole tetramer 7, and the latter furnished N-benzyl-3-trifluoroacetylindole (8). Heating 1 in aqueous methanol also yielded the trimer 4 along with 2, the N-benzylitriindolyldimethane 3, and the N-benzyltetraindolyltrimethane 5 whose structure and solid-state conformation were determined by X-ray crystallographic analysis. The results are discussed and plausible mechanisms of the reactions leading to 3-8 are presented.
Biswas, KM; Mallik, H; Saha, A; Halder, S; McPhail, AT
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