Solvent-Dependent Copper-Catalyzed Indolyl C3-Oxygenation and N1-Cyclization Reactions: Selective Synthesis of 3H-Indol-3-ones and Indolo[1,2-c]quinazolines

A simple and practical procedure for the selective preparation of 3H-indol-3-one and indolo[1,2-c]quinazoline derivatives through copper-catalyzed aerobic oxygenation and intramolecular cyclization reactions of 2-(2-amidoaryl)-1H-indoles in the presence of acid has been disdosed. Interestingly, the reaction outcomes are exclusively dependent on the reaction medium employed. With DMF as the solvent, the amide moiety of indole substrates could act as an auxiliary to enable the indole's oxygenation reaction with molecular oxygen from air as the oxidant to give 3H-indol-3-one derivatives in a highly selective manner. On the other hand, when the reactions were performed in 1,4-dioxane, the amide moiety switched to participate in an intramolecular indolyl N1-cyclization to afford indolo[1,2-c]quinazolines as the predominating products.