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

Abstract

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.