7-Phenylindolo[3,2,1-de]phenanthridin-13-one, the Vilsmeier-Haack reaction product of 1,4-diphenylcarbazole

Abstract

Formylation of 1,4-diphenylcarbazole (la) under the conditions of the Vilsmeier-Haack reaction gave 7-phenylindolo[3,2,1-de]phenanthridin-13-one (2a), which brominated to give 6-bromo-7-phenylindolo[3,2,l-de]phenanthridin-13-one (2b). Treatment of the compounds (2a) and (2b) with sodium hydride and alkyl iodides yields l-(o-lkoxycarbonylphenyl)-9-alkyl-4-phenylcarbazoles (3a) and (3b) and the 3-bromo analogue (3c), respectively. The parent compound, indolo[3,2,1-de]- phenanthridin-13-one (2c), under the same reaction conditions also gave the ring-opened compound 1-(0-methoxycarbonylphenyl)-9-methylcarbazole (3d).