Iron-catalyzed intramolecular C-H amination for the synthesis of N-H carbazoles and indoles

The development of aerobic oxidative C-H/N-H cross-coupling catalyzed by the first-row transition metals is attractive yet challenging. Here, the first iron-catalyzed intramolecular cross-dehydrogenative coupling for the synthesis of carbazoles and indoles using air as the oxidant is reported. The general and efficient protocol allows for C-N bond formation under green conditions with excellent functional group compatibility, delivering a wide range of N-H carbazoles and indoles in good yields. Impressively, all carbazoles are prepared from 2-cyclohexenyl aminoarenes with the loss of 6Hs via a C-H amination and aromatization process. Furthermore, it also works for C-O bond formation. An iron-catalyzed intramolecular dehydrogenative coupling for the synthesis of N-H carbazoles and indoles with excellent functional group tolerance using air as the terminal oxidant is reported.