FACILE SYNTHESIS OF 2-SUBSTITUTED INDOLES AND INDOLO[3,2-B] CARBAZOLES FROM 2-(BENZOTRIAZOL-1-YLMETHYL)INDOLE

Replacement of the benzotriazole moiety of N-alkyl-2-(1-benzotriazol-1-ylalkyl)indo 6 and 9, prepared from 1-propargylbenzotriazole and o-iodoaniline followed by alkylation, with Grignard reagents gave the corresponding 2-substituted indoles 10 in good yield. Treatment of compounds 6 or 9 with zinc chloride afforded 6,12-disubstituted-6,12-dihydroindolo[3,2-b]carbazoles 11 in moderate to good yields. 6,12-Disubstituted-5,11-dihydroindolo[3,2-b]carbazoles 13 were prepared readily and in good yield from 2-(benzotriazol-1-ylalkyl)indoles 8 via dimerization in the presence of zinc chloride followed by dehydrogenation on exposure to air.