Copper-catalyzed synthesis of indolyl diketones via C-H oxidation/diacylation of indoles with arylglyoxal hydrates

An expedient protocol for Cu-catalyzed C-H oxidation/diacylation of indoles with arylglyoxal hydrates to construct indolyl diketones is developed. This methodology exhibits the synthetic utility of the synthesis of an indole-alkaloid 1,2-di(1H-indol-3-yl) ethane-1,2-dione and offers a straightforward means to produce different indolyl nitrogen-containing heterocycles such as indolyl quinoxaline, indolyl hydantoin and indolyl imidazole in high yields. Preliminary mechanistic studies indicate that two proposed pathways are involved in this process.